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Biology: Topic-wise Test- 8 - NEET MCQ


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90 Questions MCQ Test - Biology: Topic-wise Test- 8

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Biology: Topic-wise Test- 8 - Question 1

“Cycloporin-A” bioactive agent that is commonly used as immunosuppressive drug is the product by the fungus that is

Detailed Solution for Biology: Topic-wise Test- 8 - Question 1

The bioactive agent Cyclosporin-A, which is commonly used as an immunosuppressive drug, is produced by the fungus Trichoderma polysporum. Here is a detailed explanation:
1. Cyclosporin-A:
- Cyclosporin-A is a potent immunosuppressive drug that is widely used in organ transplantation to prevent rejection.
- It is also used to treat autoimmune diseases such as rheumatoid arthritis and psoriasis.
2. Production by Fungus:
- Cyclosporin-A is produced by a specific strain of the fungus Trichoderma polysporum.
- This fungus is known for its ability to produce secondary metabolites with pharmaceutical importance.
3. Other Options:
- Monascus purpureus is a fungus used in the production of red yeast rice, which is used as a dietary supplement.
- Aspergillus niger is a common fungus used in the production of various enzymes and organic acids.
- Propionibacterium shermanii is a bacterium used in the production of propionic acid and Swiss cheese.
4. Conclusion:
- Among the given options, Trichoderma polysporum is the fungus that produces Cyclosporin-A.
- Its immunosuppressive properties make it valuable in the field of medicine for preventing organ rejection and treating autoimmune diseases.
Biology: Topic-wise Test- 8 - Question 2

BOD is measure of

Detailed Solution for Biology: Topic-wise Test- 8 - Question 2
BOD (Biochemical Oxygen Demand) is a measure of:
- Rate of uptake of organic matter by microbes: BOD is a measure of the amount of oxygen required by microorganisms to decompose organic matter in water. Microbes utilize oxygen during the decomposition process, and the rate at which they consume oxygen can be quantified as BOD.
- Presence of organic matter: BOD is used as an indicator of the amount of organic pollutants present in water. Higher BOD values suggest a higher concentration of organic matter, indicating the presence of pollutants that can negatively impact water quality.
- Both 1 and 2: BOD is a measure that encompasses both the rate of uptake of organic matter by microbes and the presence of organic pollutants in water. It provides information about the biological activity and the pollution level in water bodies.
- Organic and industrial matter: BOD measurement primarily focuses on the decomposition of organic matter, including both natural and anthropogenic sources. Industrial waste can contribute to BOD levels in water bodies, making BOD a useful parameter for assessing the impact of industrial activities on water quality.
In conclusion, BOD is a measure that encompasses the rate of uptake of organic matter by microbes and indicates the presence of organic pollutants, including those from industrial sources. Therefore, the correct answer is C: both 1 and 2.
Biology: Topic-wise Test- 8 - Question 3

“Lever mechanism” type of Pollination commonly observed in family

Detailed Solution for Biology: Topic-wise Test- 8 - Question 3

Labiatae are a family of flowering plants commonly known as the mint or deadnettle family. Many of the plants are aromatic in all parts and include widely used culinary herbs, such as basil, mint, rosemary, sage, savory, marjoram, oregano, hyssop, thyme, lavender, and perilla. Some species are shrubs, trees (such as teak), or, rarely, vines. Many members of the family are widely cultivated, not only for their aromatic qualities, but also their ease of cultivation, since they are readily propagated by stem cuttings.[citation needed] Besides those grown for their edible leaves, some are grown for decorative foliage, such as Coleus. Others are grown for seed, such as Salvia hispanica (chia), or for their edible tubers, such as Plectranthus edulis, Plectranthus esculentus, Plectranthus rotundifolius, and Stachys affinis (Chinese artichoke).
The family has a cosmopolitan distribution.The enlarged Lamiaceae contain about 236 genera[5] and have been stated to contain 6,900 to 7,200 species, but the World Checklist lists 7,534. The largest genera are Salvia (900), Scutellaria (360), Stachys (300), Plectranthus (300), Hyptis (280), Teucrium (250), Vitex (250), Thymus (220), and Nepeta (200).Clerodendrum was once a genus of over 400 species, but by 2010, it had been narrowed to about 150.
The family has traditionally been considered closely related to the Verbenaceae; in the 1990s, phylogenetic studies suggested that many genera classified in the Verbenaceae should be classified in the Lamiaceae or to other families in the order Lamiales

Biology: Topic-wise Test- 8 - Question 4

In Angiosperm adventive embryony develops from

Detailed Solution for Biology: Topic-wise Test- 8 - Question 4
Adventive embryony in Angiosperms:
Adventive embryony is a phenomenon in which embryos develop from cells other than the fertilized egg. In angiosperms, adventive embryony can occur through various mechanisms. However, in this specific question, adventive embryony is specifically asked to develop from diploid nucellar cells asexually (option A).
Here is a detailed explanation of the answer:
1. Angiosperm embryogenesis:
Before understanding adventive embryony, it is important to understand the normal embryogenesis process in angiosperms:
- Embryogenesis in angiosperms typically starts with the fertilization of the egg cell by the pollen tube, resulting in the formation of a zygote.
- The zygote then undergoes several divisions to form an embryo, which is enclosed within the embryo sac.
- The embryo sac contains various cells, including the egg cell, synergids, antipodal cells, and central cell.
2. Adventive embryony:
Adventive embryony is a type of embryogenesis that occurs without fertilization of the egg cell. It involves the development of embryos from cells other than the zygote.
3. Development from diploid nucellar cells:
In angiosperms, one of the mechanisms of adventive embryony is the development of embryos from diploid nucellar cells asexually. Nucellar cells are the cells present in the nucellus, a part of the ovule.
- Nucellar cells are typically haploid, but in some cases, they can be diploid.
- When diploid nucellar cells undergo asexual development, they can give rise to adventive embryos without the need for fertilization.
4. Other mechanisms of adventive embryony:
Apart from the development from diploid nucellar cells, adventive embryony can also occur through other mechanisms:
- Development from haploid nucellar cells asexually.
- Development from any cell of the embryo sac asexually.
- Development from the megaspore mother cell (MMC) sexually.
5. Importance of adventive embryony:
Adventive embryony plays a significant role in angiosperms, as it provides a means of asexual reproduction and can contribute to the production of more offspring without the need for pollination and fertilization.
In conclusion, adventive embryony in angiosperms can develop from diploid nucellar cells asexually. This mechanism allows for the formation of embryos without fertilization, leading to asexual reproduction in certain angiosperm species.
Biology: Topic-wise Test- 8 - Question 5
Most common type of Tetrad in Angiosperms are
Detailed Solution for Biology: Topic-wise Test- 8 - Question 5
Most common type of Tetrad in Angiosperms are:
Tetra hedral Tetrads
- Tetra hedral tetrads are the most common type of tetrad found in angiosperms.
- These tetrads consist of four microspores or megaspores arranged in a tetrahedral shape.
- The tetrahedral arrangement gives rise to a 3-dimensional structure.
- This type of tetrad is characteristic of angiosperms, which are flowering plants.
- The tetrahedral arrangement is thought to provide mechanical support and protection to the developing spores.
- It also allows for efficient packing of spores within the anther or ovule.
- Tetra hedral tetrads are found in both male (microspores) and female (megaspores) reproductive structures of angiosperms.
- This type of tetrad is important for the successful development and dispersal of spores in angiosperms.
In conclusion, the most common type of tetrad in angiosperms is the tetra hedral tetrad, which consists of four microspores or megaspores arranged in a tetrahedral shape. This tetrad arrangement is characteristic of angiosperms and plays a crucial role in the development and dispersal of spores.
Biology: Topic-wise Test- 8 - Question 6

 Intine of pollen grains is composed of

Detailed Solution for Biology: Topic-wise Test- 8 - Question 6
Pollen embryo sacs are also called Nemec Phenamenon, as Nemec discovered them for the first time. According to Nemec, pollen embryo sacs are produced by the repeated divisions of vegetative nucleus while the generative nucleus degenerates.
Biology: Topic-wise Test- 8 - Question 7

Metaxenia Related to

Detailed Solution for Biology: Topic-wise Test- 8 - Question 7
Metaxenia Related to
Metaxenia is a phenomenon in which the characteristics of the male parent influence the characteristics of the seed coat of a plant. It refers to the effect of the male gamete on the seed coat development. Let's explore the relationship between metaxenia and the given options:
Option A: Micropropagation
- Micropropagation refers to the process of growing plants from small plant parts, such as tissue culture or meristem culture.
- There is no direct relationship between metaxenia and micropropagation. Metaxenia is not specifically related to the propagation method used.
Option B: Agamospermy
- Agamospermy is a form of asexual reproduction in plants where seeds are formed without fertilization.
- Metaxenia can occur in both sexual and asexual reproduction, so there is no direct relationship between metaxenia and agamospermy.
Option C: Effect of male gamete over seed coat of plant
- This option accurately describes the relationship between metaxenia and the effect of the male gamete on the seed coat development.
- Metaxenia occurs when the characteristics of the male parent influence the seed coat of the plant.
Option D: Sporophytic Budding
- Sporophytic budding refers to a type of asexual reproduction where a new individual grows from a bud on the parent plant.
- There is no direct relationship between metaxenia and sporophytic budding. Metaxenia is not specifically related to the method of asexual reproduction.
Therefore, the correct answer is option C: Effect of male gamete over seed coat of plant. Metaxenia is related to the influence of the male gamete on the development of the seed coat in plants.
Biology: Topic-wise Test- 8 - Question 8
If leaf cell of pinus consist of 24 chromosome then chromosome Number in Endosperm of Pinus will be
Detailed Solution for Biology: Topic-wise Test- 8 - Question 8
In Pinus generally leaf and roots are diploid ...so 2n=24....so the endosperm that is n will be..n=12...that is half of the diploid cell.
Biology: Topic-wise Test- 8 - Question 9
During which of the following formation free nuclear division occurs
Detailed Solution for Biology: Topic-wise Test- 8 - Question 9
Formation of Free Nuclear Division:
Free nuclear division refers to the division of the nucleus without the corresponding division of the cytoplasm. It occurs in certain plant tissues during specific developmental stages.
Options:
A: Gametes
B: Endosperms
C: Flower
D: Embryo
Explanation:
Free nuclear division occurs during the formation of endosperms. Endosperm is a tissue found in the seeds of flowering plants. It provides nourishment to the developing embryo and is formed by the fusion of a sperm cell with two polar nuclei in a process called double fertilization.
During endosperm development, the nucleus undergoes multiple rounds of division without the formation of cell walls. This results in the formation of a multinucleate mass of cytoplasm, which eventually becomes the endosperm tissue. The free nuclear divisions in the endosperm are crucial for the proper development and nutrient storage in the seed.
Conclusion:
The correct answer is B: Endosperms. Free nuclear division occurs during the formation of endosperms in plants.
Biology: Topic-wise Test- 8 - Question 10
Polygonum type of embryo Sac
Detailed Solution for Biology: Topic-wise Test- 8 - Question 10
Yes, polygonum type of embryo sac is 8 nucleate. it has 3 nuclei of antipodal cells, 2 nuclei of synergids, 1 nucleus of the egg cell and the rest are the 2 polar nuclei.
Biology: Topic-wise Test- 8 - Question 11
After culturing the anther of a plant, a few diploid plants were got along with haploid plants.What of the following parts might have given rise to diploid plants?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 11
Explanation:
To determine which part might have given rise to diploid plants after culturing the anther of a plant, we need to understand the process of anther culture and the role of different parts of the anther.
Anther culture involves isolating and culturing the anther, which contains pollen grains. During this process, different parts of the anther can give rise to different types of plants. Let's analyze the options given:
A: Vegetative cell of pollen
- The vegetative cell of pollen is responsible for producing the pollen tube during fertilization.
- It does not contribute to the formation of diploid plants in anther culture.
B: Cells of anther wall
- The cells of the anther wall are somatic cells that surround the developing pollen grains.
- These cells have the potential to undergo dedifferentiation and redifferentiation, allowing them to give rise to diploid plants.
- Therefore, the cells of the anther wall have the ability to produce diploid plants in anther culture.
C: Generative cell of pollen
- The generative cell of pollen is responsible for giving rise to the sperm cells (male gametes) during fertilization.
- It does not directly contribute to the formation of diploid plants in anther culture.
D: Intine of pollen wall
- The intine of the pollen wall is the inner layer of the pollen grain wall.
- It provides protection and support to the developing pollen grain but does not have the ability to give rise to diploid plants.
Conclusion:
Based on the above analysis, the cells of the anther wall (option B) are the most likely to give rise to diploid plants after culturing the anther of a plant.
Biology: Topic-wise Test- 8 - Question 12
Nucellar embryo is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 12
Nucellar embryo is:
- Apomictic diploid.
Detailed explanation:
- The term "nucellar embryo" refers to an embryo that develops from the nucellus, a tissue found in the ovule of certain plants.
- Nucellar embryos are formed through a type of reproduction called apomixis.
- Apomixis is a form of asexual reproduction in plants where seeds are produced without fertilization.
- In apomixis, the embryo develops from the diploid cells of the nucellus, instead of being formed through the fusion of gametes.
- As a result, nucellar embryos are genetically identical to the parent plant and are therefore diploid.
- The term "amphimictic" refers to sexual reproduction, where the embryo is formed through the fusion of gametes.
- The term "haploid" refers to having a single set of chromosomes, while "diploid" refers to having two sets of chromosomes.
- Since nucellar embryos are formed through apomixis and are diploid, the correct answer is apomictic diploid (B).
Biology: Topic-wise Test- 8 - Question 13
The synthesis of sporopollenin occurs both in the tapetum and in the cytoplasm of the young spores.Sporopollenin is derived from
Detailed Solution for Biology: Topic-wise Test- 8 - Question 13
Synthesis of Sporopollenin
Sporopollenin, a complex biopolymer, is an important component of the outer layer (exine) of pollen grains and spores. The synthesis of sporopollenin occurs in two locations: the tapetum and the cytoplasm of the young spores. It is derived from oxidative polymerization of carotenoids.
Explanation:
The synthesis of sporopollenin involves the following steps:
1. Formation of primexine: In the tapetum, a layer of cells surrounding the developing pollen grains or spores, carotenoids are oxidatively polymerized to form primexine. Primexine serves as a template for the subsequent deposition of sporopollenin.
2. Deposition of sporopollenin: The primexine template is then transported to the cytoplasm of the young spores. Inside the cytoplasm, sporopollenin precursors are synthesized and deposited onto the primexine template. The deposition process involves the gradual accumulation of sporopollenin layers, leading to the formation of the mature exine.
3. Mature exine formation: As sporopollenin layers continue to accumulate, the exine becomes thicker and more resistant to environmental stresses. The mature exine provides protection to the developing pollen grains or spores during their dispersal and germination.
Conclusion:
In summary, sporopollenin is synthesized through the oxidative polymerization of carotenoids. This process occurs in both the tapetum and the cytoplasm of the young spores. Sporopollenin plays a crucial role in the development of pollen grains and spores, providing them with structural integrity and protection.
Biology: Topic-wise Test- 8 - Question 14
Which of the following are generally used in the propagation of cultivated varientes of Musa?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 14
Propagation of cultivated varieties of Musa mainly involves the use of suckers. Here is a detailed explanation:
Propagation of cultivated varieties of Musa:
- Musa is a genus of flowering plants that includes banana and plantain species.
- Propagation refers to the process of reproducing plants from existing ones, ensuring the continuation of desired traits.
- Cultivated varieties of Musa are propagated using various methods, but the most common one is through suckers.
Explanation:
- Suckers: Suckers are small shoots or shoots that arise from the base of the banana plant, near the underground rhizome.
- Suckers are genetically identical to the parent plant, preserving the desired traits of the cultivated variety.
- They can be detached from the parent plant and replanted to establish new plants.
- Suckers provide a quicker and more reliable method of propagation compared to other options.
- They also ensure the uniformity and consistency of the cultivated variety.
Other options:
- Corrm: Corrm is not a recognized term in the context of Musa propagation. It is not relevant to cultivated varieties of Musa.
- Seed: While some wild species of Musa can produce seeds, cultivated varieties rarely produce viable seeds. If seeds are obtained, they do not guarantee the replication of desired traits.
- Stem cuttings: Stem cuttings can be used for Musa propagation, but they are less commonly used compared to suckers. Cuttings taken from the stem of a mature plant can be rooted and grown into new plants. However, this method may not always produce plants with the desired traits.

In summary, the most commonly used method for propagating cultivated varieties of Musa is through suckers. Suckers ensure genetic uniformity, preserve desired traits, and provide a reliable and efficient means of propagation.
Biology: Topic-wise Test- 8 - Question 15
Which type of tapentum plays a role in the deposition of sporopollenin granules, called Ubish bodies or orbicules?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 15
The Role of Secretory Tapetum in the Deposition of Sporopollenin Granules (Ubisch Bodies or Orbicules)
Introduction:
Tapetum is a layer of cells found in the anther of flowering plants. It plays a crucial role in pollen development and serves as a nutrient source for pollen grains. Tapetum can be classified into two main types: amoeboid tapetum and secretory tapetum.
Answer:
The type of tapetum that plays a role in the deposition of sporopollenin granules, known as Ubisch bodies or orbicules, is secretory tapetum (B).
Explanation:
Here is a detailed explanation of why secretory tapetum is involved in the deposition of Ubisch bodies or orbicules:
1. Secretory Tapetum: Secretory tapetum is characterized by the production and secretion of various substances, including lipids, proteins, and sporopollenin. It is responsible for providing essential nutrients and materials required for the development of pollen grains.
2. Sporopollenin Granules: Sporopollenin is a complex biopolymer found in the outer layer of pollen grains and spores. It is highly resistant to environmental factors and provides protection to pollen grains during their development and dispersal.
3. Deposition of Ubisch Bodies or Orbicules: Ubisch bodies or orbicules are specialized sporopollenin granules found in the tapetum. They are synthesized and deposited in the tapetum cells before being transferred to the pollen grain exine (outer wall).
4. Role of Secretory Tapetum: Secretory tapetum plays a crucial role in the deposition of Ubisch bodies or orbicules by:
- Synthesizing sporopollenin granules within its cells.
- Accumulating and storing the sporopollenin granules.
- Secretion of the sporopollenin granules into the anther locule, where they come in contact with developing pollen grains.
- Facilitating the transfer of sporopollenin granules from the tapetum to the pollen grain exine.
5. Function of Ubisch Bodies or Orbicules: Ubisch bodies or orbicules have various functions, such as:
- Providing structural integrity to the pollen grain exine.
- Acting as a physical barrier against desiccation and environmental stress.
- Enhancing pollen grain viability and fertility.
In conclusion, secretory tapetum plays a vital role in the deposition of sporopollenin granules, including Ubisch bodies or orbicules. These specialized structures contribute to the development and protection of pollen grains during their maturation and dispersal.
Biology: Topic-wise Test- 8 - Question 16
Among the following which one is NOT a method of vegetative propagation ?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 16
Sowing is done by the seed which is the reproductive part of plant not the vegetative part.
Biology: Topic-wise Test- 8 - Question 17

During grafting rootstock is generally derived from a plant

Detailed Solution for Biology: Topic-wise Test- 8 - Question 17
Explanation:

During grafting, rootstock is generally derived from a plant. This means that the rootstock, which is the lower part of the graft, is taken from a different plant and joined to the scion, which is the upper part of the graft. The rootstock is chosen based on specific characteristics and traits that are desirable in the resulting grafted plant.


Reasons for selecting rootstock:

  • Efficient in water and mineral absorption: The rootstock is selected for its ability to efficiently absorb water and minerals from the soil. This ensures that the grafted plant has a strong and healthy root system.

  • Resistance to diseases: The rootstock is often chosen for its resistance to specific diseases or pests. This helps protect the grafted plant from potential infections and improves its overall health and productivity.

  • Growth of strong and healthy branches: The rootstock can also influence the growth and development of the branches of the grafted plant. By selecting a rootstock that promotes strong and healthy branch growth, the overall structure and vigor of the grafted plant can be enhanced.


Therefore, the correct answer is D: all of these. The rootstock selection plays a crucial role in the success and performance of the grafted plant.

Biology: Topic-wise Test- 8 - Question 18
Which one of the following accurately describes apospory
Detailed Solution for Biology: Topic-wise Test- 8 - Question 18
Apospory:
Formation of embryo from egg of an embryo sac developed directly from a cell of nucellus.
Apospory refers to the development of an embryo directly from a cell of the nucellus, bypassing the normal process of embryo sac formation. It is a type of asexual reproduction in plants.
Explanation:
Apospory is a form of apomixis, which is the production of seeds without fertilization. In apospory, the embryo sac develops directly from a cell of the nucellus, rather than from the megaspore mother cell.
Here is the detailed explanation of each option:
A. Formation of embryo from egg of an embryo sac developed directly from megaspore mother cell: This option does not accurately describe apospory because apospory involves the development of an embryo sac from a cell of the nucellus, not the megaspore mother cell.
B. Formation of embryo from egg of an embryo sac developed directly from a cell of nucellus: This option accurately describes apospory. The embryo sac is formed directly from a cell of the nucellus, and the embryo develops from the egg within this embryo sac.
C. Formation of embryo from nucellus: This option does not accurately describe apospory because apospory involves the development of an embryo sac from a cell of the nucellus, not the direct formation of an embryo from the nucellus itself.
D. Formation of embryo from integument: This option does not accurately describe apospory because apospory involves the development of an embryo sac from a cell of the nucellus, not the integument.
Therefore, the correct answer is B: Formation of embryo from egg of an embryo sac developed directly from a cell of nucellus.
Biology: Topic-wise Test- 8 - Question 19
SCP term Related to
Detailed Solution for Biology: Topic-wise Test- 8 - Question 19
SCP Term Related to a Yeast:
- SCP-1780: SCP-1780 is a Euclid-class SCP that refers to a colony of anomalous yeast organisms. These yeast organisms can rapidly multiply and consume any organic matter they come into contact with, including living organisms. They have the ability to break down complex substances into simpler forms, leading to their classification as a self-sustaining biological SCP.
- SCP-1861: SCP-1861 is a Keter-class SCP that involves a fungal infection caused by an anomalous strain of yeast. This infection affects humans and other living organisms, leading to various physical and psychological effects. It is highly contagious and poses a significant threat to containment.
- SCP-2354: SCP-2354 is a Safe-class SCP that refers to a strain of yeast capable of producing a substance known as "SCP-2354-A." This substance has potent antimicrobial properties and can be used to treat various infectious diseases. However, it also has the potential for misuse and must be carefully controlled.
SCP Term Related to a Prion:
- SCP-008: SCP-008 is a Euclid-class SCP that is a highly infectious prion. It causes a disease known as "SCP-008-1," which leads to rapid zombification in infected individuals. The prion can be transmitted through bodily fluids and poses a significant risk to containment.
- SCP-019: SCP-019 is a Safe-class SCP that involves a prion-infected sculpture. When exposed to living organisms, the prions within the sculpture can cause rapid degeneration and death. It is essential to handle SCP-019 with extreme caution to prevent any accidental infection.
SCP Term Related to a Big Plant:
- SCP-789-J: SCP-789-J is a Euclid-class SCP that refers to a giant sentient cactus. It possesses anomalous properties, including the ability to communicate with Foundation personnel and exhibit a playful personality. The cactus requires regular watering and sunlight to maintain its health.
- SCP-317: SCP-317 is a Safe-class SCP that involves a species of large carnivorous plants. These plants have the ability to attract and capture prey using their unique scent and appearance. They are kept in a controlled environment to prevent accidental harm to personnel.
- SCP-328: SCP-328 is a Euclid-class SCP that resembles a large, parasitic tree. It has the ability to drain the life force of nearby living organisms, causing them to wither and die. The tree requires constant monitoring to prevent it from spreading and causing harm.
Biology: Topic-wise Test- 8 - Question 20
Small Proteins produced by vertebrate cells naturally and in response to viral infections inhafiting viral multiplication are known as
Detailed Solution for Biology: Topic-wise Test- 8 - Question 20
Small Proteins produced by vertebrate cells naturally and in response to viral infections inhibiting viral multiplication are known as Interferon.
Interferons are a group of signaling proteins that are released by host cells in response to the presence of viruses. They play a crucial role in the innate immune response by inhibiting viral replication and modulating the immune system. Here is a detailed explanation of Interferons:
1. Definition:
- Interferons are small proteins that are naturally produced by vertebrate cells and are part of the body's defense mechanism against viral infections.
2. Function:
- They interfere with viral replication by inhibiting the synthesis of viral proteins and preventing the virus from spreading to neighboring cells.
- Interferons also activate immune cells, such as natural killer cells and macrophages, which help in the destruction of infected cells.
- They enhance the expression of major histocompatibility complex (MHC) molecules on the surface of cells, which aids in the recognition and elimination of infected cells by cytotoxic T cells.
3. Types of Interferons:
- There are three main types of interferons: alpha, beta, and gamma.
- Interferon-alpha and interferon-beta are produced by most cells in response to viral infections, while interferon-gamma is mainly produced by immune cells.
4. Mechanism of Action:
- Interferons bind to specific receptors on the surface of neighboring cells, triggering a signaling cascade that activates antiviral genes.
- This leads to the production of various proteins that inhibit viral replication and enhance the immune response.
5. Therapeutic Applications:
- Interferons have been used therapeutically to treat viral infections, such as hepatitis B and C, and certain types of cancer.
- They are also being investigated for their potential role in the treatment of COVID-19.
In conclusion, Interferons are small proteins produced by vertebrate cells in response to viral infections. They play a vital role in inhibiting viral multiplication and modulating the immune response.
Biology: Topic-wise Test- 8 - Question 21
Cultivation of Bt cotton has been much in the news. The prefix Bt means
Detailed Solution for Biology: Topic-wise Test- 8 - Question 21
Bt cotton is a genetically modified variety of cotton that has been widely cultivated. The prefix "Bt" stands for Bacillus thuringiensis, which is a type of bacteria that produces a toxin harmful to certain pests. Here's a detailed explanation of the meaning of the Bt prefix:
Bacillus thuringiensis:
- Bacillus thuringiensis is a naturally occurring soil bacterium that produces proteins toxic to certain insects.
- This bacterium has been used for many years as a biological pesticide in agriculture to control pests.
Endotoxin gene:
- The Bt cotton variety is genetically modified to carry a specific gene from Bacillus thuringiensis.
- This gene allows the cotton plants to produce a protein that is toxic to specific pests, such as the bollworm and pink bollworm.
- The protein is only toxic to these pests and does not harm other organisms, including humans.
Biotechnology:
- Bt cotton is produced using biotechnology techniques, which involve the manipulation of an organism's genetic material.
- Restriction enzymes and ligases are used to cut and join DNA segments, allowing the insertion of the endotoxin gene into the cotton plant's genome.
- This genetic modification enables the cotton plants to produce the toxin and protect themselves against insect pests.
Advantages of Bt cotton:
- Bt cotton has been widely adopted by farmers due to its effectiveness in controlling pests.
- It reduces the need for chemical insecticides, leading to a decrease in environmental pollution and potential harm to farmers' health.
- Bt cotton also increases crop yields by minimizing the damage caused by insect pests.
- The cultivation of Bt cotton has contributed to the reduction in pesticide use and increased profitability for farmers in many regions.
In conclusion, the prefix Bt in Bt cotton refers to the genetic modification of the cotton plant to carry an endotoxin gene from Bacillus thuringiensis. This modification allows the plant to produce a protein toxic to specific pests, providing effective pest control and reducing the reliance on chemical insecticides. The cultivation of Bt cotton has brought numerous benefits to farmers and the environment.
Biology: Topic-wise Test- 8 - Question 22
Oldest viable seed Reported Recently is that of Lupin (Lupinus arcticus), excavated from Arctic tundra. The seed germinate and flowered after an estimated record of 10,000yr of dormancy. Arecent record of 2000 year -old viable seed of date Palm. discovered during the archeological excavation at king Herod’s palace near dead sea. Viability of seed canbe tested by use of chemical that is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 22
Viability Testing of Seeds
There are various methods to test the viability of seeds, including the use of chemicals. In this case, the chemical that can be used to test the viability of the seed is "T T C." Let's discuss this in detail:
1. Viability Testing:
- Viability testing is performed to determine whether a seed is capable of germination and producing a viable plant.
- It is particularly important for studying the longevity and dormancy of seeds.
2. Importance of Viability Testing:
- Viability testing helps in understanding the lifespan and dormancy period of seeds.
- It can provide insights into the survival strategies of plants under different conditions.
- Viability testing is crucial for conservation and restoration efforts, as it helps in selecting seeds with the highest chances of successful germination.
3. Chemical Test for Viability:
- One of the chemicals that can be used to test the viability of seeds is "T T C."
- T T C stands for 2,3,5-triphenyl tetrazolium chloride, which is a redox indicator commonly used to assess seed viability.
- This chemical is colorless and water-soluble but gets converted to a red formazan dye in the presence of dehydrogenase enzymes found in living cells.
- If the seed is viable and contains living cells, the T T C solution will turn red, indicating the presence of active enzymes and hence, viability.
4. Other Methods for Seed Viability Testing:
- Apart from chemical testing, there are other methods to test seed viability, including:
- Germination tests: Seeds are placed under favorable conditions to observe their ability to sprout and develop into seedlings.
- Tetrazolium chloride staining: Similar to T T C, this method uses tetrazolium chloride to stain viable tissues.
- Electrical conductivity tests: Measures the leakage of electrolytes from the seeds, which indicates their viability.
- DNA-based methods: Molecular techniques can be employed to assess the genetic material and viability of seeds.
In conclusion, the chemical "T T C" (2,3,5-triphenyl tetrazolium chloride) can be used to test the viability of seeds. Viability testing is crucial for understanding the longevity and dormancy of seeds and plays a significant role in conservation and restoration efforts.
Biology: Topic-wise Test- 8 - Question 23
In Agave vegitative reproduction is carried out through
Detailed Solution for Biology: Topic-wise Test- 8 - Question 23
Agave vegetative reproduction:
Agave plants are known for their ability to reproduce vegetatively, meaning they can generate new plants without the need for seeds or sexual reproduction. This process is carried out through bulbils.
What are bulbils?
Bulbils are small, bulb-like structures that form on the stem or in the leaf axils of the Agave plant. They serve as a means of asexual reproduction and are responsible for generating new offspring plants.
Process of vegetative reproduction:
The vegetative reproduction in Agave through bulbils involves the following steps:
1. Bulbil formation: Bulbils develop from the stem or in the leaf axils of the Agave plant. They are small and bulb-shaped structures that contain all the necessary genetic material for the formation of a new plant.
2. Maturation: As the bulbils mature, they develop roots and shoots, preparing themselves for detachment from the parent plant.
3. Detachment: Once mature, the bulbils detach from the parent plant either naturally or through external factors such as wind, rain, or animal movement.
4. Dispersal: The detached bulbils are then dispersed to new locations, where they have the potential to grow into new Agave plants. This allows Agave plants to colonize different areas and expand their population.
5. Growth and development: When the bulbils settle in suitable conditions, they establish roots and shoots, eventually growing into mature Agave plants.
Advantages of vegetative reproduction in Agave:
- Efficient reproduction: Vegetative reproduction allows Agave plants to produce offspring without the need for pollination or the production of seeds. This process is faster and more efficient than sexual reproduction.
- Genetic similarity: As bulbils are formed from the parent plant, they carry the exact genetic material, resulting in offspring that are genetically identical to the parent. This ensures the preservation of desirable traits.
- Adaptation to harsh environments: Agave plants are commonly found in arid and semiarid regions. Vegetative reproduction through bulbils allows them to colonize new areas and adapt to harsh environmental conditions more effectively.
- Increased population: By producing multiple bulbils, Agave plants can generate a higher number of offspring, leading to an increase in population size.
Conclusion:
Agave plants utilize bulbils for their vegetative reproduction, allowing them to efficiently produce offspring without the need for seeds or sexual reproduction. This process provides advantages such as genetic similarity, adaptation to harsh environments, and increased population size.
Biology: Topic-wise Test- 8 - Question 24
“LAB” can help in
Detailed Solution for Biology: Topic-wise Test- 8 - Question 24
Explanation:
The term "LAB" refers to Lactic Acid Bacteria, which is a type of bacteria commonly used in various applications.
LAB can help in:
- Checking disease: LAB is commonly used in medical and diagnostic laboratories to identify and diagnose various diseases. It can be used to detect the presence of specific bacteria or viruses in a patient's sample, aiding in the diagnosis and treatment of diseases.
- Fermentation: LAB plays a crucial role in the fermentation process. It is used to convert sugars into lactic acid, which helps in preserving and flavoring various food products. LAB is commonly used in the production of yogurt, cheese, sauerkraut, pickles, and other fermented foods.
- Roquefort cheese making: LAB is specifically used in the production of Roquefort cheese. It helps in the development of the cheese's unique flavor and texture by contributing to the fermentation process.
- None of these: This option is incorrect as LAB can indeed help in checking disease, fermentation, and Roquefort cheese making.
Therefore, the correct answer is C. "Roquefort cheese making."
Biology: Topic-wise Test- 8 - Question 25

Pseudomanas putida known as

Detailed Solution for Biology: Topic-wise Test- 8 - Question 25
Pseudomonas putida: A Detailed Explanation
Pseudomonas putida is a species of bacteria that belongs to the Pseudomonas genus. It is a Gram-negative, rod-shaped bacterium that is commonly found in soil and freshwater environments. This bacterium has several unique characteristics and plays various roles in the ecosystem.
Key Points:
- Pseudomonas putida: A species of bacteria belonging to the Pseudomonas genus.
- Gram-negative: The bacterium has a cell wall structure that stains pink during the Gram staining procedure.
- Rod-shaped: Pseudomonas putida has a cylindrical shape.
- Environmental distribution: It is commonly found in soil and freshwater environments.
- Ecosystem role: Pseudomonas putida plays a crucial role in bioremediation, as it has the ability to degrade various pollutants and contaminants.
- Biodegradation capabilities: This bacterium can degrade a wide range of organic compounds, including aromatic hydrocarbons, pesticides, and toxic chemicals.
- Plant interactions: Pseudomonas putida can establish beneficial relationships with plants. It can promote plant growth, enhance nutrient uptake, and provide protection against pathogens.
- Industrial applications: Due to its biodegradation capabilities, Pseudomonas putida is used in various industries for the treatment of wastewater, the production of biofuels, and the removal of pollutants.
- Research interest: Scientists are studying Pseudomonas putida extensively to understand its genetic and metabolic capabilities, which can potentially be harnessed for various applications.
In conclusion, Pseudomonas putida is a versatile bacterium with significant environmental and industrial importance. Its ability to degrade pollutants and establish beneficial interactions with plants makes it a valuable asset in various fields. Ongoing research continues to explore its potential applications, making it an exciting area of study.
Biology: Topic-wise Test- 8 - Question 26

Plague is caused by

Detailed Solution for Biology: Topic-wise Test- 8 - Question 26
Plague is caused by:
- Yersinia pestis: Yersinia pestis is the bacterium responsible for causing plague. It is a Gram-negative, rod-shaped bacterium that primarily affects rodents and is transmitted to humans through fleas.


Explanation:
Plague, also known as the Black Death, is a severe infectious disease caused by the bacterium Yersinia pestis. It has been responsible for several major pandemics throughout history, including the Black Death in the 14th century, which decimated the population of Europe.
Here is a detailed explanation of each option and why Yersinia pestis is the correct answer:
- Trichinella pestis: Trichinella is a genus of parasitic roundworms that causes the disease trichinosis. Trichinosis is primarily acquired by consuming raw or undercooked meat infected with Trichinella larvae, not by fleas or rodents. Therefore, Trichinella pestis is not the correct answer for the cause of plague.
- Leishmania donovani: Leishmania donovani is a parasite that causes a tropical disease called visceral leishmaniasis or kala-azar. It is transmitted to humans through the bite of infected sandflies, not through fleas or rodents. Therefore, Leishmania donovani is not the correct answer for the cause of plague.
- Corynebacterium rependonicum: Corynebacterium rependonicum is a species of bacteria that is mainly associated with infections in horses and other animals. It does not cause plague in humans. Therefore, Corynebacterium rependonicum is not the correct answer for the cause of plague.
- Yersinia pestis: Yersinia pestis is the correct answer for the cause of plague. It is a bacterium that primarily affects rodents, especially rats, and is transmitted to humans through fleas that have bitten infected animals. Yersinia pestis can cause three forms of plague in humans: bubonic, septicemic, and pneumonic. Bubonic plague is the most common form and is characterized by swollen lymph nodes (buboes). Septicemic plague occurs when the bacteria spread to the bloodstream, and pneumonic plague affects the lungs and can be transmitted from person to person through respiratory droplets.
In conclusion, the correct answer for the cause of plague is Yersinia pestis, a bacterium transmitted to humans through fleas that have bitten infected rodents.
Biology: Topic-wise Test- 8 - Question 27
Terramycin is obtained from
Detailed Solution for Biology: Topic-wise Test- 8 - Question 27
Terramycin is obtained from Streptomyces rimosus.
Explanation:
Terramycin is an antibiotic medication that is used to treat various bacterial infections. It belongs to the tetracycline group of antibiotics. The tetracyclines are produced by certain strains of soil bacteria called Streptomyces.
Key Points:
- Terramycin is obtained from Streptomyces rimosus, a species of bacteria.
- Streptomyces rimosus is known for its ability to produce the antibiotic Terramycin.
- Streptomyces rimosus is a Gram-positive bacteria that forms filamentous structures called mycelia.
- The mycelia of Streptomyces rimosus contain specialized structures called spores, which are responsible for the production of Terramycin.
- The spores of Streptomyces rimosus are harvested and processed to extract Terramycin, which is then purified and formulated into various dosage forms for medical use.
Conclusion:
Terramycin is obtained from the bacteria Streptomyces rimosus. The bacteria produce the antibiotic through the formation of spores, which are then processed to extract Terramycin.
Biology: Topic-wise Test- 8 - Question 28
Botulism caused by Clostridium botulinum is due to toxin produced by the bacterium. Only 60 billion of a gram is sufficient to kill a human. Which of the following is not a characteristic feature of this bacteians ?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 28
Characteristics of Clostridium botulinum:
1. It inhabits soils around the world: This is a characteristic feature of Clostridium botulinum. The bacterium is commonly found in soil, sediments, and aquatic environments worldwide.
2. Its spores grow in nutrient-rich medium: Clostridium botulinum can form spores that are capable of surviving in harsh conditions, including nutrient-rich environments. This allows the bacterium to persist and potentially cause infection when conditions are favorable.
3. Vomiting, constipation, paralysis of eyes & throat are common symptoms of botulism: Botulism, caused by the toxin produced by Clostridium botulinum, is characterized by symptoms such as vomiting, constipation, blurred vision, drooping eyelids, difficulty swallowing, and muscle weakness. These symptoms are a result of the neurotoxin affecting the nervous system.
4. Bacterium cannot live without oxygen: This statement is not a characteristic feature of Clostridium botulinum. In fact, Clostridium botulinum is an anaerobic bacterium, meaning it can survive and grow in the absence of oxygen. It thrives in low-oxygen environments such as the soil and the gastrointestinal tract.
Therefore, the correct answer is A: It inhabits soils around the world.
Biology: Topic-wise Test- 8 - Question 29

Escherichia coli, a moneran, is extensively used in biological reaserch because

Detailed Solution for Biology: Topic-wise Test- 8 - Question 29
Why Escherichia coli is extensively used in biological research:
1. Easy to handle: Escherichia coli, commonly known as E. coli, is a bacterium that is relatively easy to handle in the laboratory setting. It has simple growth requirements and can be easily manipulated for various experimental purposes.
2. Easily available: E. coli is a commonly found bacterium in the environment, especially in the intestines of humans and other animals. It can be easily obtained from various sources, such as fecal samples or commercially available strains.
3. Easily cultured in the laboratory: E. coli can be easily cultured in the laboratory using standard microbiological techniques. It grows quickly and can be maintained on simple nutrient agar or broth media. This allows researchers to obtain large quantities of the bacterium for experiments.
4. Genetic tractability: E. coli has a well-characterized and easily manipulated genome. It has been extensively studied and many genetic tools and techniques have been developed for its analysis. This makes it an ideal model organism for studying various biological processes, including gene expression, DNA replication, and protein synthesis.
5. Similarity to higher organisms: Despite being a bacterium, E. coli shares many similarities with higher organisms, including humans. It possesses many of the same fundamental cellular processes and molecular mechanisms. Studying E. coli can provide valuable insights into the functioning of more complex organisms.
In conclusion, Escherichia coli is extensively used in biological research because of its ease of handling, availability, ease of cultivation in the laboratory, genetic tractability, and its similarity to higher organisms. These characteristics make it a versatile and widely used model organism for various scientific studies.
Biology: Topic-wise Test- 8 - Question 30

Dissolved oxygen is removed from boiler feed water to prevent

Detailed Solution for Biology: Topic-wise Test- 8 - Question 30
Why is dissolved oxygen removed from boiler feed water?
There are several reasons why dissolved oxygen is removed from boiler feed water. These include:
1. Prevention of microorganism growth:
- Dissolved oxygen can promote the growth of microorganisms such as bacteria and algae in the boiler feed water.
- Microorganism growth can lead to biofouling and the formation of biofilms on heat transfer surfaces.
- This can reduce heat transfer efficiency, increase corrosion rates, and result in the formation of deposits.
2. Prevention of corrosion:
- Dissolved oxygen in the water can cause corrosion in the boiler and other metal components.
- Oxygen reacts with the metal surface to form iron oxide (rust), which weakens the metal and can lead to leaks or equipment failure.
- Removing dissolved oxygen helps to minimize the corrosive effects and extend the lifespan of the boiler system.
3. Prevention of bubble formation:
- Dissolved oxygen can also contribute to the formation of bubbles or foam in the boiler.
- These bubbles can interfere with the proper circulation of water and steam, leading to reduced heat transfer and potential damage to equipment.
4. Maintenance of boiler efficiency:
- The presence of dissolved oxygen in boiler feed water can reduce the efficiency of the boiler system.
- Oxygen can react with chemicals in the water, leading to the formation of scale and deposits on heat transfer surfaces.
- This reduces heat transfer efficiency, increases energy consumption, and decreases overall boiler performance.
In conclusion, the removal of dissolved oxygen from boiler feed water is essential to prevent microorganism growth, corrosion, bubble formation, and loss in boiler efficiency. By eliminating dissolved oxygen, the boiler system can operate more efficiently, reduce the risk of equipment damage, and prolong its lifespan.
Biology: Topic-wise Test- 8 - Question 31

In India the commonly used method for sewage treatment is

Detailed Solution for Biology: Topic-wise Test- 8 - Question 31
Commonly Used Method for Sewage Treatment in India: Activated Sludge Process
The commonly used method for sewage treatment in India is the activated sludge process. This process involves the following steps:
1. Preliminary Treatment:
- Screening: The sewage is passed through screens to remove large objects like sticks, plastics, and rags.
- Grit Chamber: The sewage is then directed to a grit chamber where sand, gravel, and other heavy particles settle down.
2. Primary Treatment:
- Sedimentation Tank: The sewage is transferred to a sedimentation tank where the suspended solids settle down as sludge at the bottom.
- Sludge Removal: The settled sludge is removed and sent for further treatment.
3. Secondary Treatment:
- Aeration Tank: The partially treated sewage is mixed with activated sludge in an aeration tank. The activated sludge is a mixture of bacteria and other microorganisms.
- Aeration: Air is continuously supplied to the aeration tank to provide oxygen for the growth of aerobic bacteria. These bacteria consume organic matter in the sewage.
- Mixing: The sewage and activated sludge are mixed thoroughly to ensure contact between the microorganisms and the organic matter.
4. Final Treatment:
- Sedimentation Tank: The sewage from the aeration tank is transferred to a sedimentation tank where the activated sludge settles down as sludge.
- Sludge Removal: The settled sludge is removed and sent for further treatment or disposal.
- Treated Effluent: The clarified effluent is discharged into natural water bodies or subjected to tertiary treatment for further purification.
5. Tertiary Treatment (Optional):
- Filtration: The treated effluent may undergo filtration through sand filters or other filtration systems to remove any remaining suspended solids.
- Disinfection: The filtered effluent may be disinfected using chlorine or ultraviolet (UV) radiation to kill any remaining pathogens.
Overall, the activated sludge process is an effective method for sewage treatment in India as it helps in removing organic matter, suspended solids, and harmful microorganisms from the sewage, making it safe for disposal or reuse.
Biology: Topic-wise Test- 8 - Question 32
Phytoremediation is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 32
Phytoremediation is the use of plants for removing toxicants from soil or water.
Phytoremediation is a sustainable and cost-effective approach to environmental cleanup. It harnesses the natural abilities of certain plants to absorb, detoxify, and accumulate pollutants from contaminated sites. Here is a detailed explanation of phytoremediation:
1. Definition:
- Phytoremediation is the process of using plants to clean up and remove contaminants from polluted soil, water, or air.
2. Mechanisms:
- Phytoremediation can occur through various mechanisms, including absorption, adsorption, volatilization, and transformation.
- Plants can absorb contaminants through their roots and transport them to their shoots, where they can be stored or transformed into less harmful substances.
- Some plants can also release enzymes or chemicals that can break down or transform pollutants in the soil or water.
3. Types of Phytoremediation:
- Phytoextraction: Certain plants, known as hyperaccumulators, can accumulate high levels of heavy metals in their tissues. These plants are grown in contaminated areas and then harvested, effectively removing the pollutants from the site.
- Phytostabilization: This approach uses plants to immobilize or stabilize contaminants in the soil, preventing their movement and reducing their bioavailability.
- Phytodegradation: Some plants have the ability to break down or degrade organic pollutants, such as petroleum hydrocarbons or pesticides, through the action of enzymes produced by their roots or associated microorganisms.
- Phytovolatilization: Certain plants can absorb volatile contaminants from the soil or water and release them into the atmosphere through their leaves, effectively removing them from the environment.
4. Advantages of Phytoremediation:
- Environmentally friendly: Phytoremediation is a natural and sustainable approach that does not involve the use of chemicals or energy-intensive processes.
- Cost-effective: Phytoremediation can be more cost-effective compared to traditional remediation methods, such as excavation and disposal.
- Aesthetic benefits: Phytoremediation can enhance the visual appeal of contaminated sites by establishing green spaces and vegetation.
- Habitat restoration: Phytoremediation can help restore habitats by improving soil quality and promoting the growth of beneficial organisms.
5. Limitations of Phytoremediation:
- Time-consuming: Phytoremediation is often a slow process that requires a long-term commitment.
- Specific plant requirements: Different plants have varying abilities to tolerate and remediate specific contaminants, so careful selection of suitable plant species is crucial.
- Site conditions: The success of phytoremediation depends on factors such as soil type, pH, nutrient availability, and climate, which may limit its applicability in certain locations.
In conclusion, phytoremediation is a valuable technique that utilizes plants to remove toxicants from soil or water. It offers several advantages, including its environmentally friendly nature, cost-effectiveness, and potential for habitat restoration. However, its effectiveness depends on careful selection of appropriate plant species and consideration of site-specific conditions.
Biology: Topic-wise Test- 8 - Question 33

Which of the following is included in biopesticides ?

Detailed Solution for Biology: Topic-wise Test- 8 - Question 33
Answer:
What are biopesticides?
Biopesticides are a type of pesticide that are derived from natural sources such as animals, plants, bacteria, and fungi. They are used to control pests, including insects, weeds, and diseases, in agriculture and other settings.
Inclusion of biopesticides:
The correct option for the inclusion of biopesticides is C: Viruses, bacteria, fungi, protozoa and mites. Biopesticides can be categorized into different types based on their active ingredients. These include:
- Viruses: Certain viruses, known as viral biopesticides, are used to control insect pests. These viruses infect and kill specific pests, providing an effective and environmentally friendly pest control solution.
- Bacteria: Bacterial biopesticides are derived from naturally occurring bacteria such as Bacillus thuringiensis (Bt). These bacteria produce toxins that are toxic to specific pests, including certain insects and nematodes.
- Fungi: Fungal biopesticides are derived from naturally occurring fungi such as Beauveria bassiana and Metarhizium anisopliae. These fungi infect and kill pests such as insects and mites.
- Protozoa: Certain protozoa, such as Nosema locustae, are used as biopesticides to control specific pests. These protozoa infect and kill pests like grasshoppers and locusts.
- Mites: Some mites, such as Phytoseiulus persimilis, are used as biopesticides to control pest mites. These predatory mites feed on and control pest mite populations.
Conclusion:
Biopesticides include a range of natural organisms such as viruses, bacteria, fungi, protozoa, and mites. These organisms can be used as effective and environmentally friendly alternatives to synthetic pesticides in pest control.
Biology: Topic-wise Test- 8 - Question 34
Which of the following can be controlled by using biopesticides ?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 34
Insects:
- Biopesticides can control various types of insects that damage crops or cause other problems.
- They can be effective against pests such as aphids, caterpillars, beetles, flies, and mosquitoes.
Diseases:
- Biopesticides can also be used to control plant diseases caused by bacteria, fungi, viruses, and other pathogens.
- They can help prevent the spread and development of diseases such as blight, mildew, rust, and various viral infections.
Weeds:
- Biopesticides can provide control over unwanted weeds that compete with crops for resources.
- They can be effective against various types of weeds, including broadleaf weeds, grasses, and sedges.
All of them:
- Biopesticides have the potential to control all of the above-mentioned pests, including insects, diseases, and weeds.
- They can be used as an alternative to conventional chemical pesticides, offering a more environmentally friendly option for pest control.
In conclusion, biopesticides can be used to control a wide range of pests, including insects, diseases, and weeds. They offer a safer and more sustainable approach to pest management, reducing the reliance on chemical pesticides and minimizing the potential negative impacts on the environment and human health.
Biology: Topic-wise Test- 8 - Question 35
Biofertilisers include
Detailed Solution for Biology: Topic-wise Test- 8 - Question 35
Biofertilisers include:
- Blue-green algae: Blue-green algae, also known as cyanobacteria, are photosynthetic bacteria that can fix atmospheric nitrogen into usable forms for plants. They form symbiotic associations with certain crop plants and provide them with nitrogen.
- Rhizobia: Rhizobia are a group of nitrogen-fixing bacteria that form symbiotic associations with the roots of leguminous plants. They convert atmospheric nitrogen into ammonia, which can be used by the plants for growth and development.
- Other nitrogen-fixing bacteria: Apart from rhizobia, there are other types of nitrogen-fixing bacteria that can form associations with various plants. These bacteria convert atmospheric nitrogen into forms that can be readily taken up by plants.
- Mycorrhiza fungi: Mycorrhiza fungi form mutualistic associations with the roots of plants. They enhance the nutrient uptake of plants, especially phosphorus, by increasing the surface area for absorption and releasing enzymes that help in nutrient acquisition.
Benefits of biofertilisers:
- Biofertilisers provide a natural and sustainable source of nutrients for plants.
- They improve soil fertility and structure, leading to better nutrient retention and water-holding capacity.
- Biofertilisers enhance plant growth and productivity, leading to increased crop yields.
- They reduce the need for synthetic chemical fertilisers, thereby minimizing environmental pollution and degradation.
- Biofertilisers promote the development of beneficial soil microorganisms, which contribute to overall soil health.
In conclusion, biofertilisers such as blue-green algae, rhizobia, other nitrogen-fixing bacteria, and mycorrhiza fungi play a crucial role in improving soil fertility and providing essential nutrients to plants. They offer several benefits for sustainable agriculture and environmental conservation.
Biology: Topic-wise Test- 8 - Question 36
Denitrirfication carreid out by
Detailed Solution for Biology: Topic-wise Test- 8 - Question 36
Denitrification carried out by Thiobacillus:
Thiobacillus is a group of bacteria that can carry out denitrification, which is the process of converting nitrates (NO3-) into nitrogen gas (N2). Here's a detailed explanation of how Thiobacillus performs denitrification:
1. Introduction to denitrification:
- Denitrification is an anaerobic process that occurs in environments with low oxygen levels.
- It helps to reduce the concentration of nitrates in the soil or water, preventing their accumulation.
2. Role of Thiobacillus in denitrification:
- Thiobacillus is a versatile group of bacteria that can perform different biochemical processes, including denitrification.
- They have the enzyme nitrate reductase, which catalyzes the conversion of nitrates into nitrites (NO2-).
- Another enzyme, nitrite reductase, then converts the nitrites into nitric oxide (NO).
3. Denitrification steps carried out by Thiobacillus:
- Nitric oxide produced by Thiobacillus is further converted into nitrous oxide (N2O) by the enzyme nitric oxide reductase.
- Finally, nitrous oxide is converted into nitrogen gas (N2) by the enzyme nitrous oxide reductase.
- This completes the denitrification process, as nitrogen gas is released into the atmosphere.
4. Importance of denitrification:
- Denitrification is crucial for maintaining the nitrogen cycle in ecosystems.
- It helps to balance the nitrogen levels in the soil, preventing nitrogen overload and its negative impacts on plant growth.
- Denitrification also plays a role in reducing the release of nitrous oxide, a potent greenhouse gas, into the atmosphere.
In conclusion, Thiobacillus is a bacteria group that performs denitrification by converting nitrates into nitrogen gas. This process helps regulate nitrogen levels in the environment and plays a crucial role in maintaining ecosystem balance.
Biology: Topic-wise Test- 8 - Question 37
Fungi are also known to form symbiotic association with plants which one Taxa (genus) of Fungi commonly form mycorrhiza
Detailed Solution for Biology: Topic-wise Test- 8 - Question 37
Genus of Fungi commonly forming mycorrhiza:
1. Glomus:
- Glomus is a genus of fungi that commonly forms mycorrhiza with plants.
- Mycorrhiza is a symbiotic association between fungi and the roots of plants.
- Glomus fungi form arbuscular mycorrhiza, which is the most common type of mycorrhiza found in plants.
- Arbuscular mycorrhiza involves the formation of specialized structures called arbuscules within the plant roots, which facilitate nutrient exchange between the fungus and the plant.
- This association benefits both the fungus and the plant, as the fungus receives nutrients from the plant while providing the plant with increased nutrient absorption capabilities.
2. Morels and Agaricus:
- Morels (genus Morchella) and Agaricus (genus Agaricus) are types of fungi but they do not commonly form mycorrhiza with plants.
- Morels are saprophytic fungi that obtain nutrients from decaying organic matter.
- Agaricus fungi, also known as mushrooms, are generally saprophytic or parasitic in nature.
3. Yeast:
- Yeast (genus Saccharomyces) is a type of fungus that is commonly used in baking and brewing.
- Yeast species do not typically form mycorrhiza with plants.
Therefore, the correct answer is C: Glomus as this genus of fungi commonly forms mycorrhiza with plants.
Biology: Topic-wise Test- 8 - Question 38
Idea of “Predation” utilized in
Detailed Solution for Biology: Topic-wise Test- 8 - Question 38
Predation in Biocontrol:
- Predation is the act of one organism (predator) capturing and feeding on another organism (prey) for survival.
- In biocontrol, predation is utilized as a natural method to control pests and invasive species.
- Predatory organisms are introduced or encouraged in an ecosystem to prey on pests, reducing their population and minimizing damage to crops or the environment.
Role of Predation in Biocontrol:
- Predatory organisms play a crucial role in maintaining the balance of ecosystems by controlling the population of pests and invasive species.
- They act as natural enemies of pests, targeting and consuming them, thus reducing their numbers and preventing infestations.
- Predators can also disrupt the life cycle of pests by feeding on their eggs, larvae, or pupae, thereby preventing their reproduction and growth.
- Predation in biocontrol is an environmentally friendly approach as it reduces the reliance on chemical pesticides, which can have harmful effects on the environment and human health.
Examples of Predation in Biocontrol:
- Ladybugs (Coccinellidae family) are commonly used as predators in biocontrol programs. They feed on aphids, mites, and other plant pests.
- Nematodes (roundworms) are used to control soil-dwelling pests like grubs, caterpillars, and root-knot nematodes. They infect and kill these pests, reducing their population.
- Predatory mites, such as Phytoseiulus persimilis, are effective in controlling spider mites, which can cause significant damage to plants.
- Birds, bats, and other vertebrates can also act as predators in biocontrol, feeding on insects and rodents that can damage crops.
Benefits of Predation in Biocontrol:
- Predation-based biocontrol methods are sustainable and environmentally friendly.
- They reduce the use of chemical pesticides, leading to a healthier ecosystem and lower risks of pesticide-related pollution.
- Predatory organisms can adapt and evolve along with the pests, providing long-term control.
- Predation in biocontrol is a cost-effective approach compared to chemical pesticides, as it utilizes natural processes and organisms already present in the ecosystem.
Conclusion:
- Predation plays a vital role in the field of biocontrol by using natural predators to control pest populations.
- This approach provides a sustainable and environmentally friendly alternative to chemical pesticides.
- By understanding the ecological interactions between predators and pests, biocontrol programs can effectively manage pest populations and protect crops and ecosystems.
Biology: Topic-wise Test- 8 - Question 39
The virus which are able to attack on insect and other arthropods as pathogen - etc
Detailed Solution for Biology: Topic-wise Test- 8 - Question 39
Pathogens that can attack insects and other arthropods:
Baculovirus:
- Baculoviruses are a group of viruses that specifically infect insects and other arthropods.
- They are known for their ability to cause diseases in insects, including caterpillars, moths, and beetles.
- Baculoviruses can be highly pathogenic to their hosts, causing significant mortality rates.
- They have been extensively studied and used as biological control agents for pest insects in agriculture.
- Baculoviruses are typically spread through direct contact between infected and susceptible insects.
HIV Nucleopolyhedro virus:
- HIV Nucleopolyhedro virus is not a virus that specifically targets insects and arthropods.
- HIV is a human immunodeficiency virus that primarily infects humans and weakens the immune system.
Adenovirus:
- Adenoviruses primarily infect mammals, including humans, and can cause respiratory, gastrointestinal, and eye infections.
- They are not known to infect insects and arthropods.
Oncovirus:
- Oncoviruses are a group of viruses that can cause cancer in their hosts, primarily mammals.
- They are not known to infect insects and arthropods.
Therefore, the correct answer is C: Baculovirus, as it is the virus that can attack insects and other arthropods as a pathogen.
Biology: Topic-wise Test- 8 - Question 40
The Technology of Biogas production was developed in India mainly due to efforts of
Detailed Solution for Biology: Topic-wise Test- 8 - Question 40
The Technology of Biogas production was developed in India mainly due to efforts of:
A: IARI
- Indian Agricultural Research Institute (IARI) played a significant role in the development of biogas production technology in India.
- It conducted extensive research and experiments to identify suitable feedstocks and optimize the anaerobic digestion process.
- IARI developed and promoted the use of high-quality biogas plants that could efficiently convert organic waste into biogas.
B: KVIC
- Khadi and Village Industries Commission (KVIC) also contributed to the development of biogas production technology in India.
- KVIC provided training and financial support to individuals and communities for setting up biogas plants.
- It promoted the use of biogas as a clean and renewable energy source, particularly in rural areas.
C: CPCB
- Central Pollution Control Board (CPCB) played a role in ensuring the environmental sustainability of biogas production.
- It formulated guidelines and regulations for the safe and efficient operation of biogas plants.
- CPCB also monitored and enforced compliance with these guidelines to prevent any adverse environmental impacts.
D: Both 1 and 2
- The development of biogas production technology in India was a result of the combined efforts of IARI and KVIC.
- IARI's research and technical expertise, along with KVIC's support in terms of training and financing, contributed to the successful adoption and implementation of biogas technology in the country.
Overall, the technology of biogas production in India owes its development to the collaborative efforts of IARI and KVIC, with CPCB playing a regulatory role to ensure environmental sustainability.
Biology: Topic-wise Test- 8 - Question 41
MOEF (Delhi) has initiated Ganga Action Plan in
Detailed Solution for Biology: Topic-wise Test- 8 - Question 41
Initiation of Ganga Action Plan by MOEF (Delhi)
Answer: A. 1985
The Ministry of Environment and Forests (MOEF) in Delhi initiated the Ganga Action Plan in 1985 to address the pollution and degradation of the Ganges river. Here is a detailed explanation of the Ganga Action Plan:
1. Purpose: The Ganga Action Plan was launched with the aim of reducing pollution and improving the water quality of the Ganges river, which is considered sacred by millions of people in India.
2. Objectives: The plan focused on the following objectives:
- Interception, diversion, and treatment of domestic sewage and industrial effluents to prevent them from entering the river.
- Creation of sewage treatment plants (STPs) and effluent treatment plants (ETPs) along the river to treat the waste before it is discharged.
- Conservation and restoration of the river's ecological balance.
- Awareness and involvement of the local communities in the conservation efforts.
3. Phases: The Ganga Action Plan was implemented in two phases:
- Phase I (1985-2000): This phase focused on the construction of sewage treatment plants in major towns along the river and the interception and diversion of domestic sewage and industrial effluents.
- Phase II (2001-2020): This phase aimed at further improving the water quality, covering smaller towns and cities, and promoting decentralized sewage treatment systems.
4. Implementation: The implementation of the Ganga Action Plan involved the following steps:
- Identification of polluted stretches of the river and setting up monitoring stations.
- Construction of sewage treatment plants and effluent treatment plants.
- Development of sewerage networks and sewage pumping stations.
- Awareness campaigns and community participation through NGOs and local bodies.
5. Challenges and Achievements: The Ganga Action Plan faced several challenges, including inadequate funding, lack of proper maintenance of sewage treatment plants, and the continuous discharge of untreated waste into the river. However, it also achieved some significant milestones, such as the construction of numerous sewage treatment plants, reduction in the pollution load, and increased awareness among the local communities.
6. Recent Initiatives: In recent years, the Indian government has launched the Namami Gange program, an integrated conservation mission for the Ganges river, to further address the pollution and ecological issues. This program aims to focus on comprehensive river basin management, river surface cleaning, and the promotion of sustainable sanitation practices.
Overall, the initiation of the Ganga Action Plan by MOEF (Delhi) in 1985 marked an important step towards addressing the pollution and degradation of the Ganges river. Despite challenges, it has played a crucial role in improving the water quality and raising awareness about the importance of preserving this sacred river.
Biology: Topic-wise Test- 8 - Question 42
Blood clots can be remove from resepective blood vessel of patients who has gone myocordial infraction leading to heart attack by use of
Detailed Solution for Biology: Topic-wise Test- 8 - Question 42
Removal of Blood Clots in Patients with Myocardial Infarction
Introduction:
Blood clots can form in the blood vessels of patients who have experienced a myocardial infarction (heart attack). These blood clots can be dangerous as they can block the blood flow to the heart, leading to further complications. There are several treatment options available to remove blood clots and restore normal blood flow.
Treatment Options:
1. Statin:
- Statins are a class of medication commonly used to lower cholesterol levels in the blood.
- While statins are effective in preventing the formation of new blood clots, they do not directly remove existing blood clots.
- Therefore, statins alone may not be sufficient for removing blood clots in patients with myocardial infarction.
2. Streptokinase:
- Streptokinase is a clot-dissolving medication that can be administered to patients with myocardial infarction.
- It works by activating a substance in the blood called plasminogen, which then converts into plasmin, an enzyme responsible for breaking down blood clots.
- Streptokinase is effective in dissolving blood clots and restoring blood flow in patients with myocardial infarction.
3. Citric Acid:
- Citric acid is not commonly used for the removal of blood clots in patients with myocardial infarction.
- While citric acid may have some anti-coagulant properties, it is not considered a primary treatment option for this purpose.
4. Ethanol:
- Ethanol is not a recommended treatment for removing blood clots in patients with myocardial infarction.
- Ethanol is commonly used as a disinfectant or solvent and does not have specific clot-dissolving properties.
Conclusion:
Among the given options, the most appropriate treatment for removing blood clots in patients with myocardial infarction is streptokinase. Streptokinase is a clot-dissolving medication that can effectively dissolve blood clots and restore normal blood flow to the heart. It is important to consult with a healthcare professional for proper diagnosis and treatment recommendations.
Biology: Topic-wise Test- 8 - Question 43
Pollen consumtion has been claimed to increase the performance of athelete and race horse pollen grains are commonly utilized in the form of
Detailed Solution for Biology: Topic-wise Test- 8 - Question 43
Explanation:
Pollen consumption has been claimed to increase the performance of athletes and racehorses. Pollen grains are commonly utilized in the form of pollen tablets and syrup.
Reasons why pollen consumption may increase performance:
- Nutritional content: Pollen grains are rich in vitamins, minerals, amino acids, and antioxidants, which can provide essential nutrients for improved performance.
- Energy boost: Pollen contains carbohydrates, which can provide a quick source of energy for athletes and racehorses during intense physical activity.
- Anti-inflammatory properties: Pollen contains anti-inflammatory compounds that can help reduce muscle inflammation and promote faster recovery after exercise.
- Respiratory benefits: Pollen has been suggested to improve respiratory function, which can be beneficial for endurance athletes and racehorses during intense workouts or races.
Why pollen tablets and syrup are commonly used:
- Convenience: Pollen tablets and syrup provide a convenient and easy way to consume pollen without the need for processing or preparation.
- Controlled dosage: Pollen tablets and syrup allow for a controlled dosage, ensuring athletes and racehorses receive the optimal amount of pollen for performance enhancement.
- Taste: Pollen tablets and syrup are often formulated to have a palatable taste, making them easier to consume for both athletes and racehorses.
In conclusion: Pollen consumption in the form of pollen tablets and syrup is commonly used to potentially improve the performance of athletes and racehorses due to their nutritional content, energy-boosting properties, anti-inflammatory effects, and potential respiratory benefits.
Biology: Topic-wise Test- 8 - Question 44
“Sludge” term used in CETP particularly during
Detailed Solution for Biology: Topic-wise Test- 8 - Question 44
Sludge in CETP:
Definition: Sludge refers to the semi-solid residual material that is produced during the treatment of wastewater in a Centralized Effluent Treatment Plant (CETP). It is the byproduct of the treatment process and consists of solid waste, organic matter, and other pollutants that have been removed from the wastewater.
Usage: The term "sludge" is commonly used in CETP during the secondary treatment stage.
Explanation:
Primary Treatment:
- Primary treatment is the initial stage of wastewater treatment in CETP.
- It involves the physical removal of large solids and floating debris from the wastewater.
- Sludge is not typically referred to during this stage as it mainly focuses on the separation of solid materials.
Secondary Treatment:
- Secondary treatment follows primary treatment and aims to remove dissolved and suspended organic matter from the wastewater.
- It includes biological processes such as activated sludge, trickling filters, or rotating biological contactors.
- During these processes, microorganisms break down organic matter and produce sludge as a byproduct.
- Sludge is formed due to the settling or flocculation of the microorganisms and organic solids.
- This sludge is commonly referred to as "activated sludge" or "biological sludge" in CETP.
Tertiary Treatment:
- Tertiary treatment is the final stage of wastewater treatment and focuses on further polishing the effluent to meet specific quality standards.
- It includes processes like filtration, chemical coagulation, and disinfection.
- Sludge is not typically mentioned during this stage as the focus is on the removal of fine particles and disinfection.
Incineration:
- Incineration is a waste treatment process that involves the combustion of organic substances in the presence of oxygen.
- It is often used as a method to dispose of sludge generated during wastewater treatment.
- However, the term "sludge" itself is not specific to incineration and can be associated with different treatment stages.
In conclusion, the term "sludge" is commonly used in CETP during the secondary treatment stage, where biological processes generate sludge as a byproduct. It is important to manage and dispose of sludge properly to minimize environmental impacts and ensure the effective treatment of wastewater.
Biology: Topic-wise Test- 8 - Question 45
The masses of Bacteria associated with fungal filament to form meshlike structure called as
Detailed Solution for Biology: Topic-wise Test- 8 - Question 45
Explanation:
The correct answer is B: Flocs. When bacteria associate with fungal filaments, they form a meshlike structure called flocs. Here is a detailed explanation:
Definition:
- Flocs are aggregates of suspended particles that come together to form a meshlike structure.
- These particles can include bacteria, fungi, algae, organic matter, and other substances.
Formation of Flocs:
- Bacteria can associate with fungal filaments, which are thread-like structures produced by fungi.
- This association leads to the formation of flocs, where the bacteria and fungal filaments intertwine and create a meshlike structure.
- The flocs can vary in size and shape depending on the type of bacteria and fungi involved.
Functions of Flocs:
- Flocs have several important functions in various environmental processes, such as wastewater treatment.
- In wastewater treatment, the flocs help in the removal of organic matter, nutrients, and other pollutants.
- They enhance the settling and filtration processes by increasing the size and density of the particles, allowing them to be easily separated from the water.
- Flocs also provide a protective environment for bacteria, allowing them to survive and carry out their metabolic activities more efficiently.
Applications:
- Flocs are commonly used in various wastewater treatment processes, such as activated sludge systems and biological nutrient removal.
- They can also be found in natural environments, such as rivers and lakes, where they play a role in the cycling of nutrients and organic matter.
In conclusion, when bacteria associate with fungal filaments, they form a meshlike structure called flocs. These flocs have important functions in wastewater treatment and natural environments.
Biology: Topic-wise Test- 8 - Question 46
Exogenous budding requires
Detailed Solution for Biology: Topic-wise Test- 8 - Question 46
Exogenous budding requires:
- Mitotic cell division: Exogenous budding is a form of asexual reproduction where a new individual is formed by the outgrowth and subsequent detachment of a bud from the parent organism. This process involves mitotic cell division, where the parent cell divides into two identical daughter cells.
- Gemmules: Gemmules are small, resistant structures that can be found in some organisms, such as freshwater sponges. However, exogenous budding does not require gemmules for reproduction.
- Meiosis: Meiosis is a type of cell division that occurs in sexually reproducing organisms, where the number of chromosomes is reduced by half. Exogenous budding, being a form of asexual reproduction, does not involve meiosis.
- Gametes: Gametes are specialized cells involved in sexual reproduction. However, exogenous budding does not involve the fusion of gametes, as it is a form of asexual reproduction.
Therefore, the correct answer is D: mitotic cell division. Exogenous budding requires mitotic cell division for the formation of a new individual.
Biology: Topic-wise Test- 8 - Question 47
Plasmodium is an example of
Detailed Solution for Biology: Topic-wise Test- 8 - Question 47
Plasmodium is an example of anisogamy.
Anisogamy is a type of sexual reproduction in which the gametes (reproductive cells) of the male and female individuals are different in size and/or structure. In this process, the smaller gamete is called the male gamete or sperm, and the larger gamete is called the female gamete or egg.
Plasmodium is a genus of parasitic protozoa that causes malaria in humans and other animals. It has a complex life cycle that involves both sexual and asexual reproduction. During sexual reproduction, Plasmodium exhibits anisogamy, where the male gametes (microgametes) are small and motile, while the female gametes (macrogametes) are larger and non-motile.
Here are some key points:
- Plasmodium is a parasitic protozoan that causes malaria.
- It undergoes both sexual and asexual reproduction.
- During sexual reproduction, Plasmodium exhibits anisogamy.
- Anisogamy is a type of sexual reproduction where the male and female gametes are different in size and/or structure.
- Plasmodium's male gametes (microgametes) are small and motile.
- Plasmodium's female gametes (macrogametes) are larger and non-motile.
In conclusion, Plasmodium is an example of anisogamy, as it exhibits sexual reproduction with distinct male and female gametes that differ in size and mobility.
Biology: Topic-wise Test- 8 - Question 48
Hermaphroditim refers to
Detailed Solution for Biology: Topic-wise Test- 8 - Question 48
Hermaphroditism refers to the presence of male and female gonads in an individual.
- Hermaphroditism is a biological condition in which an organism possesses both male and female reproductive organs or gonads.
- This condition can occur in various animal species, including humans, plants, and some invertebrates.
- The term hermaphroditism is derived from the Greek mythological figure Hermaphroditus, who possessed the physical traits of both sexes.
- In hermaphroditic individuals, both male and female reproductive organs are present, allowing them to produce both sperm and eggs.
- This condition can manifest in different ways, such as simultaneous hermaphroditism, where an individual can self-fertilize or cross-fertilize with another hermaphroditic individual.
- Some examples of hermaphroditic organisms include certain species of fish, snails, worms, and plants.
- Hermaphroditism can be advantageous in environments where finding a mate for reproduction is challenging or rare.
- In humans, hermaphroditism is rare and is often associated with intersex conditions, where an individual has atypical physical characteristics of both sexes.
- Medical interventions and support are often provided to individuals with intersex conditions to ensure their physical and psychological well-being.
In summary, hermaphroditism refers to the presence of both male and female gonads in an individual, allowing them to produce both sperm and eggs.
Biology: Topic-wise Test- 8 - Question 49
Which of the following is a primary sex organ?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 49
Primary Sex Organ:
- The primary sex organs, also known as gonads, are responsible for producing gametes (reproductive cells) and secreting sex hormones.
- In females, the primary sex organ is the ovary.
Explanation:
- The ovary is a primary sex organ in females.
- It is responsible for producing eggs (ova) and secreting hormones such as estrogen and progesterone.
- Ovaries are paired organs located on either side of the uterus in the pelvic cavity.
- They contain thousands of follicles, each of which houses an immature egg.
- During each menstrual cycle, one of the follicles develops and releases a mature egg through a process called ovulation.
- If the egg is fertilized by sperm, it may implant in the uterus and develop into a pregnancy.
- If the egg is not fertilized, it disintegrates and is shed along with the uterine lining during menstruation.
- The ovaries also play a crucial role in hormone production, which regulates the menstrual cycle and influences secondary sexual characteristics in females.
Summary:
- The primary sex organ in females is the ovary.
- It is responsible for producing eggs and secreting hormones necessary for reproductive processes and secondary sexual characteristics.
Biology: Topic-wise Test- 8 - Question 50
The tubules inside the testis are called
Detailed Solution for Biology: Topic-wise Test- 8 - Question 50
The tubules inside the testis are called seminiferous tubules.
The seminiferous tubules are a crucial component of the male reproductive system. These tubules are responsible for the production of sperm, also known as spermatogenesis. Here's a detailed explanation of the seminiferous tubules:
Structure and Function:
- The seminiferous tubules are long, coiled tubes that are located within the testes.
- They are surrounded by a layer of supportive cells called Sertoli cells.
- The tubules are lined with cells called germ cells, which develop into sperm cells.
- The Sertoli cells provide structural support and nourishment to the developing sperm cells.
- Within the seminiferous tubules, the process of spermatogenesis takes place, which involves the production, maturation, and release of sperm cells.
Spermatogenesis:
- Spermatogenesis begins with the division of germ cells called spermatogonia.
- These cells undergo a series of mitotic divisions to produce primary spermatocytes.
- The primary spermatocytes then undergo meiosis to form secondary spermatocytes.
- Further divisions lead to the formation of spermatids, which eventually mature into sperm cells.
- The mature sperm cells are released into the lumen of the seminiferous tubules.
Hormonal Regulation:
- The production of sperm in the seminiferous tubules is regulated by hormones, specifically follicle-stimulating hormone (FSH) and testosterone.
- FSH stimulates the Sertoli cells to support the development and maturation of sperm cells.
- Testosterone, produced by the Leydig cells located in the testes, plays a crucial role in spermatogenesis.
Overall, the seminiferous tubules are vital structures within the testes that facilitate the production of sperm through the process of spermatogenesis.
Biology: Topic-wise Test- 8 - Question 51
The prostate gland is comparable to
Detailed Solution for Biology: Topic-wise Test- 8 - Question 51
Prostate gland is present in males.It helps in producing semen.There is noo such type of gland in females.
Biology: Topic-wise Test- 8 - Question 52
The penis contains
Detailed Solution for Biology: Topic-wise Test- 8 - Question 52
The penis contains:
- Erectile tissue: The penis is made up of spongy tissue called erectile tissue. This tissue can fill with blood and become rigid, allowing the penis to become erect during sexual arousal.
- Involuntary muscles: The penis also contains involuntary muscles known as smooth muscles. These muscles help to regulate blood flow into and out of the erectile tissue, allowing for erection and flaccidity.
Explanation:
The penis is an external male reproductive organ that plays a crucial role in sexual function and reproduction. It consists of several components, including erectile tissue and involuntary muscles.
Erectile tissue:
- The penis contains three columns of erectile tissue: two corpora cavernosa on the upper side and one corpus spongiosum on the underside. These columns are made up of spongy tissue filled with numerous small blood vessels called sinusoids.
- During sexual stimulation, the smooth muscles in the walls of the blood vessels relax, allowing increased blood flow into the sinusoids. This causes the erectile tissue to fill with blood, resulting in an erection.
Involuntary muscles:
- Smooth muscles are found throughout the penis, including in the walls of the blood vessels within the erectile tissue.
- These smooth muscles contract and relax to regulate blood flow. When relaxed, they allow increased blood flow into the erectile tissue, leading to an erection. When contracted, they restrict blood flow, causing the penis to become flaccid.
It is important to note that while the penis contains erectile tissue and involuntary muscles, it does not contain bones. The penis relies on the coordination of these tissues and muscles to achieve and maintain an erection during sexual arousal.
Biology: Topic-wise Test- 8 - Question 53
Corpus luteum is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 53
Corpus luteum is a mass of tissue
- The corpus luteum is a temporary endocrine structure that forms in the ovary after the release of an egg during ovulation.
- It is derived from the ruptured follicle that released the egg.
- The corpus luteum secretes hormones, particularly progesterone, which is important for the maintenance of pregnancy.
- It plays a crucial role in the menstrual cycle, preparing the uterus for possible implantation of a fertilized egg.
- If fertilization does not occur, the corpus luteum degenerates and becomes a scar tissue called the corpus albicans.
- However, if fertilization occurs, the corpus luteum continues to produce progesterone to support the early stages of pregnancy until the placenta takes over hormone production.
Therefore, the correct answer is A: a mass of tissue.
Biology: Topic-wise Test- 8 - Question 54
The uterus in humans is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 54
The Uterus in Humans
The uterus is a vital organ in the female reproductive system responsible for nurturing and protecting a developing fetus during pregnancy. It is a hollow, muscular organ located in the pelvis, between the bladder and rectum. In humans, the uterus is pear-shaped and undergoes changes throughout a woman's menstrual cycle and during pregnancy.
Characteristics of the Uterus:
- Shape: The uterus in humans is pear-shaped, with a wider upper part called the fundus and a narrower lower part known as the cervix.
- Size: The size of the uterus can vary among individuals but is typically about the size of a closed fist.
- Structure: The uterus consists of three layers: the innermost layer called the endometrium, the middle layer of smooth muscle called the myometrium, and the outermost layer known as the perimetrium.
- Function: The main function of the uterus is to support the implantation and development of a fertilized egg into a fetus during pregnancy. It also plays a role in menstruation and childbirth.
Importance of the Uterus:
- Pregnancy: The uterus provides a safe and nourishing environment for the developing fetus during pregnancy. It undergoes significant changes to accommodate the growing baby, including stretching and expanding.
- Menstruation: The lining of the uterus, known as the endometrium, thickens and sheds during the menstrual cycle if pregnancy does not occur. This process is responsible for menstruation.
- Childbirth: During childbirth, the uterus contracts to facilitate the delivery of the baby. The strong muscular walls of the uterus help in pushing the baby out through the cervix and vagina.
In conclusion, the human uterus is pear-shaped and plays a crucial role in pregnancy, menstruation, and childbirth. Its unique structure and function are essential for the reproductive health of women.
Biology: Topic-wise Test- 8 - Question 55
The posterior narrow portion between the uterus and vagina is called
Detailed Solution for Biology: Topic-wise Test- 8 - Question 55
The posterior narrow portion between the uterus and vagina is called the cervix. The cervix is an important anatomical structure in the female reproductive system. Here is a detailed explanation of the cervix:
Anatomy of the Cervix:
- The cervix is a cylindrical or conical-shaped structure located at the lower end of the uterus.
- It connects the uterus to the upper part of the vagina.
- The cervix has two main parts: the ectocervix (lower part) and the endocervix (upper part).
- The ectocervix is the part of the cervix that is visible and can be examined during a pelvic examination.
Functions of the Cervix:
- The cervix serves as a protective barrier between the vagina and the uterus.
- It produces mucus that changes in consistency throughout the menstrual cycle, which helps in sperm transport and fertility.
- During pregnancy, the cervix undergoes changes to support the growing fetus and eventually dilates during labor to allow the passage of the baby.
Importance of the Cervix:
- The cervix plays a crucial role in reproductive health and fertility.
- It is a site where cervical cancer can develop, and regular cervical screenings (Pap tests) are important for early detection and prevention.
- The cervix also acts as a barrier to prevent infections from reaching the uterus.
In conclusion, the posterior narrow portion between the uterus and vagina is called the cervix. It has important functions in reproductive health and plays a role in fertility, pregnancy, and the prevention of cervical cancer.
Biology: Topic-wise Test- 8 - Question 56

Fertilisation occurs

Detailed Solution for Biology: Topic-wise Test- 8 - Question 56
Explanation:
The correct answer is A: 48 hours after ovulation. Here is the detailed explanation:
- Fertilisation is the process by which a sperm cell fuses with an egg cell to form a fertilised egg or zygote.
- Ovulation is the release of an egg from the ovary, which typically occurs around the middle of a woman's menstrual cycle.
- After ovulation, the egg travels through the fallopian tube towards the uterus.
- Sperm cells can survive in the female reproductive system for up to 5 days.
- However, the egg is only viable for fertilisation for about 12-24 hours after ovulation.
- Therefore, for fertilisation to occur, intercourse must take place prior to ovulation or within a day or two after ovulation.
- The sperm cells need time to travel through the female reproductive system to reach the fallopian tube where fertilisation occurs.
- It takes approximately 6-8 hours for the sperm to reach the fallopian tube.
- Once in the fallopian tube, the sperm can survive for another 48-72 hours.
- Therefore, fertilisation is most likely to occur within 48 hours after ovulation.
In conclusion, fertilisation occurs approximately 48 hours after ovulation.
Biology: Topic-wise Test- 8 - Question 57

Anestrus is

Detailed Solution for Biology: Topic-wise Test- 8 - Question 57
Anestrus refers to the inactive breeding state in animals. During this phase, there is a temporary cessation of ovarian activity and no sexual behavior or receptivity to mating. Here are the details explaining why option B is the correct answer:
- Anestrus:
- Anestrus is a phase in the estrous cycle of female mammals, which includes non-primate mammals like dogs, cats, cows, pigs, etc.
- It is the period of sexual inactivity between two estrus cycles.
- During anestrus, there is no follicular development, ovulation, or corpus luteum formation.
- It is characterized by a lack of interest in mating, absence of fertile periods, and no visible signs of estrus (heat).
- Other options:
- Option A: An active breeding state is not correct since anestrus is the opposite of an active breeding state.
- Option C: Anestrus is not a name for the oviduct, which is a part of the female reproductive system responsible for transporting eggs from the ovary to the uterus.
- Option D: Anestrus is not a name for the follicular cavity, which is the fluid-filled space within the ovary where the follicles develop.
In conclusion, option B is the correct answer as anestrus represents the inactive breeding state in animals.
Biology: Topic-wise Test- 8 - Question 58
In which of the following does the periodic production of estrogen not occur throughout the year?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 58
Estrogen Production in Various Animals
A: Cow
- In cows, the periodic production of estrogen occurs throughout the year.
- They have a reproductive cycle known as estrous cycle, which involves regular periods of heat or estrus.
- During estrus, cows release estrogen and are receptive to mating.
B: Buffalo
- In buffaloes, the periodic production of estrogen occurs throughout the year.
- Similar to cows, buffaloes also have an estrous cycle and exhibit regular periods of heat.
C: Deer
- In deer, the periodic production of estrogen does not occur throughout the year.
- Deer have a reproductive cycle known as the rut, which typically occurs in the fall.
- During the rut, male deer (bucks) compete for females (does) and estrogen is released to signal the females' fertility.
D: Human
- In humans, the periodic production of estrogen occurs throughout the year.
- Women experience menstrual cycles, where the levels of estrogen fluctuate.
- Estrogen is responsible for controlling the reproductive system and preparing the body for potential pregnancy.
Conclusion
- Among the given options, the periodic production of estrogen does not occur throughout the year in deer (Option C).
- Cows, buffaloes, and humans all experience regular periods of estrogen production.
Biology: Topic-wise Test- 8 - Question 59
Vitellogenesis occurs during
Detailed Solution for Biology: Topic-wise Test- 8 - Question 59
Vitellogenesis occurs when the oocyte reaches the diplotene stage of meiotic prophase. ..the vitellogenesis, the process by which yolk accumulates in the cytoplasm of an ovarian oocyte.
Biology: Topic-wise Test- 8 - Question 60

Which statement is incorrect ?

Detailed Solution for Biology: Topic-wise Test- 8 - Question 60

The incorrect statement is C: The endometrium is a part of the testis.
Explanation:
The endometrium is the inner lining of the uterus, not a part of the testis. It undergoes cyclic changes during the menstrual cycle and is shed during menstruation. The testis, on the other hand, is a male reproductive organ responsible for producing sperm and testosterone.
Let's break down the statements to understand why the other options are correct:
A: The liberated oocyte of a woman is in the secondary oocyte stage.
- This statement is correct. After ovulation, the oocyte is released from the ovary and is in the secondary oocyte stage. It will only complete meiosis if fertilization occurs.
B: A vasectomized person ejects seminal fluid without sperms.
- This statement is correct. Vasectomy is a surgical procedure that involves cutting or blocking the vas deferens, the tubes that carry sperm from the testes. As a result, a vasectomized person can still ejaculate seminal fluid, but it does not contain sperm.
D: The middle piece of the sperm possesses mitochondria and a centriole.
- This statement is correct. The middle piece of the sperm contains mitochondria, which provide energy for the sperm's motility, and a centriole, which plays a role in fertilization.
In conclusion, the incorrect statement is C: The endometrium is a part of the testis. The endometrium is not a part of the testis but is the inner lining of the uterus.
Biology: Topic-wise Test- 8 - Question 61
Which one is not related to reproductive system?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 61
The reproductive system is a collection of organs and structures that are involved in the production of offspring. It includes organs such as the ovaries, testes, uterus, and fallopian tubes. These organs are responsible for processes such as fertilization, pregnancy, and childbirth.
However, one of the options mentioned, micturition, is not related to the reproductive system. Micturition refers to the process of urination or the expulsion of urine from the bladder. It is a part of the urinary system, which is responsible for the production, storage, and elimination of urine. The urinary system includes organs such as the kidneys, bladder, ureters, and urethra.
To summarize, while parturition, menopause, and menarche are all processes related to the reproductive system, micturition is a process related to the urinary system and not directly involved in reproduction.
Biology: Topic-wise Test- 8 - Question 62
Leydig cells are found in the
Detailed Solution for Biology: Topic-wise Test- 8 - Question 62
Leydig cells are found in the testis.
Leydig cells, also known as interstitial cells of the testis, are found within the testicular interstitium. These cells are responsible for the production of testosterone, the primary male sex hormone.
Key Points:
- Leydig cells are found in the testis.
- They are located in the testicular interstitium.
- Leydig cells produce testosterone.
- Testosterone is the primary male sex hormone.
Explanation:
- Leydig cells are specialized cells that are found in the testis, specifically in the testicular interstitium.
- The testicular interstitium is the tissue that surrounds the seminiferous tubules, where sperm production takes place.
- Leydig cells are responsible for the production of testosterone, which plays a crucial role in male reproductive development and function.
- Testosterone is responsible for the development of male secondary sexual characteristics, such as facial hair growth, deepening of the voice, and muscle development.
- These cells respond to luteinizing hormone (LH) secreted by the pituitary gland, which stimulates testosterone production.
- Leydig cells are not found in the ovaries, thyroid, or pituitary gland. They are specific to the testis.
Biology: Topic-wise Test- 8 - Question 63
Which one is not related to the reproductive phase of life
Detailed Solution for Biology: Topic-wise Test- 8 - Question 63
Explanation:
The question asks which option is not related to the reproductive phase of life. We need to identify the option that does not pertain to reproductive processes.
Puberty:
- Puberty is the stage of development where a child's body matures and becomes capable of reproduction.
- It is marked by the onset of secondary sexual characteristics such as breast development in females and the growth of facial hair in males.
Menstruation:
- Menstruation is a monthly process in which the lining of the uterus is shed.
- It is a part of the menstrual cycle, which is necessary for reproduction.
Gestation:
- Gestation refers to the period of time during which a fetus develops within the mother's uterus.
- It is a crucial part of the reproductive process and leads to the birth of offspring.
Conclusion:
- All the options - puberty, menstruation, and gestation - are related to the reproductive phase of life.
- Therefore, the correct answer is D: none of these, as all the options mentioned are related to the reproductive phase of life.
Biology: Topic-wise Test- 8 - Question 64
When a dominant allele at one locus and the recessive allele at the other locus produce the same phenotypic effect,the ratio of dominant and recessive epistasis would be
Detailed Solution for Biology: Topic-wise Test- 8 - Question 64
The correct ratio of dominant and recessive epistasis when a dominant allele at one locus and the recessive allele at the other locus produce the same phenotypic effect is 13:3.
Explanation:
- Epistasis is a type of gene interaction where the alleles at one locus mask or modify the phenotypic expression of alleles at another locus.
- In this case, the dominant allele at one locus is epistatic to the recessive allele at the other locus, meaning it masks the expression of the recessive allele.
- When the dominant allele at one locus and the recessive allele at the other locus produce the same phenotypic effect, it means that the dominant allele is overriding the expression of the recessive allele, regardless of whether it is present or not.
- The ratio of dominant and recessive epistasis can be calculated using the dihybrid cross ratio formula: 9:3:3:1.
- Since the dominant and recessive alleles produce the same phenotypic effect, the ratio of dominant and recessive epistasis can be simplified to 13:3.
Therefore, the correct answer is B. 13 : 3.
Biology: Topic-wise Test- 8 - Question 65
Yeast (Saccharomyces cerevisiae) is used in the industrial production of
Detailed Solution for Biology: Topic-wise Test- 8 - Question 65
Yeast (Saccharomyces cerevisiae) is used in the industrial production of ethanol.
Explanation:
Yeast, specifically Saccharomyces cerevisiae, is widely used in the industrial production of ethanol. Here's how it happens:
1. Fermentation Process:
- Yeast is added to a mixture containing sugar (often derived from crops like corn or sugarcane) and water.
- The yeast metabolizes the sugar through a process called fermentation.
- During fermentation, yeast breaks down the sugar molecules into ethanol and carbon dioxide.
2. Ethanol Production:
- The ethanol produced during fermentation is then extracted from the mixture.
- It undergoes various purification processes to remove impurities and increase its concentration.
- The final product is ethanol, which can be used for a wide range of applications, including fuel, alcoholic beverages, and industrial solvents.
3. Importance of Yeast:
- Yeast plays a crucial role in this process as it is responsible for the conversion of sugar into ethanol.
- Saccharomyces cerevisiae is a preferred yeast strain due to its ability to efficiently ferment sugars and tolerate the ethanol produced.
- It is a well-studied and safe yeast strain used in industrial-scale ethanol production.
Therefore, yeast (Saccharomyces cerevisiae) is extensively used in the industrial production of ethanol.
Biology: Topic-wise Test- 8 - Question 66
The recessive genes produce the following type of comb in fowls
Detailed Solution for Biology: Topic-wise Test- 8 - Question 66
Recessive Genes and Types of Combs in Fowls
Recessive Genes:
- Recessive genes are genetic traits that are expressed only when an individual has two copies of the gene.
- In fowls, there are various recessive genes that determine the type of comb they have.
Types of Combs:
1. Single Comb (A):
- The single comb is the most common type of comb found in fowls.
- It is characterized by a single, flat comb with evenly spaced serrations.
- The single comb is controlled by a dominant gene, so it is not produced by recessive genes.
2. Almond Comb (B):
- The almond comb is a recessive trait in fowls.
- It is characterized by a small, round comb with a smooth surface.
- Fowls with almond combs have a unique appearance.
3. Grape Comb (C):
- The grape comb is not produced by recessive genes.
- It is a result of a genetic mutation called the "rose comb" mutation.
4. Pea Comb (D):
- The pea comb is a recessive trait in fowls.
- It is characterized by a small, compact comb with three distinct rows of serrations.
- Fowls with pea combs have a distinctive and attractive comb shape.
Conclusion:
- Among the mentioned types of combs, the recessive gene produces the pea comb (D) in fowls.
- The single comb (A) is controlled by a dominant gene, while the almond comb (B) and grape comb (C) are not produced by recessive genes.
- Understanding the genetics behind comb types in fowls can help breeders selectively breed for desired comb shapes.
Biology: Topic-wise Test- 8 - Question 67
Pure vaccines are
Detailed Solution for Biology: Topic-wise Test- 8 - Question 67
Pure vaccines are
- MHC antigens: MHC antigens are molecules that are found on the surface of cells and play a critical role in the immune response. However, pure vaccines are not MHC antigens.
- Monoclonal antibodies: Monoclonal antibodies are laboratory-produced antibodies that can specifically target and bind to certain substances in the body. Pure vaccines are not monoclonal antibodies.
- Bacteria's proteins: Some vaccines are made from proteins derived from bacteria, but not all pure vaccines are bacteria's proteins.
- Certain proteins: Pure vaccines are certain proteins that are specifically selected to trigger an immune response against a particular pathogen or disease. These proteins can be derived from various sources, including bacteria, viruses, or other organisms.
Therefore, the correct answer is:
B: certain proteins
Biology: Topic-wise Test- 8 - Question 68
The enzyme used to cut the DNA molecule is
Detailed Solution for Biology: Topic-wise Test- 8 - Question 68
Enzyme used to cut the DNA molecule is:
A: Restriction endonucleases
- Restriction endonucleases are enzymes that recognize specific DNA sequences and cut the DNA at or near these sequences.
- They are produced by bacteria as a defense mechanism against foreign DNA, such as viral DNA.
- Restriction endonucleases cleave the phosphodiester bonds between nucleotides, resulting in DNA fragments with sticky or blunt ends.
- There are different types of restriction endonucleases, classified based on their recognition site and cutting pattern.
- They are widely used in molecular biology techniques such as DNA cloning, genetic engineering, and DNA fingerprinting.
B: 2-galatosidase
- 2-galactosidase is an enzyme that catalyzes the hydrolysis of lactose into glucose and galactose.
- It is not involved in cutting the DNA molecule.
C: DNA-ligase
- DNA ligase is an enzyme that joins DNA fragments together by catalyzing the formation of phosphodiester bonds between the fragments.
- It is not used to cut the DNA molecule.
D: DNA-polymerases
- DNA polymerases are enzymes that synthesize new DNA strands using existing DNA templates.
- They are involved in DNA replication and repair, but not in cutting the DNA molecule.
Therefore, the correct answer is A: Restriction endonucleases.
Biology: Topic-wise Test- 8 - Question 69
Universal donor belongs to the blood group
Detailed Solution for Biology: Topic-wise Test- 8 - Question 69
Universal Donor Belongs to the Blood Group O
The blood group O is considered the universal donor because individuals with blood type O can donate blood to individuals with any other blood type. Here's a detailed explanation:
Understanding Blood Types:
- Blood types are determined by the presence or absence of certain antigens on the surface of red blood cells.
- The two main antigens used to classify blood types are A and B.
- Blood type A has the A antigen, blood type B has the B antigen, blood type AB has both A and B antigens, and blood type O has neither A nor B antigens.
Compatibility of Blood Types:
- When it comes to blood transfusions, compatibility between the donor and recipient is crucial to prevent adverse reactions.
- People with blood type O are considered universal donors because their blood does not have the A or B antigens that can trigger an immune response in the recipient.
- Therefore, blood type O can be safely transfused to individuals with blood types A, B, AB, or O.
Reasons Why Blood Type O is the Universal Donor:
- Individuals with blood type O have naturally occurring antibodies against both A and B antigens.
- These antibodies can react with the A and B antigens present in other blood types, potentially causing a severe immune response.
- However, since blood type O does not have A or B antigens, their blood can be transfused into any other blood type without triggering an immune reaction.
Other Considerations:
- While blood type O is considered the universal donor, it is important to note that there are other factors to consider when matching blood for transfusions, such as the Rh factor.
- The Rh factor refers to another antigen present on the surface of red blood cells. Individuals can be either Rh positive (Rh+) or Rh negative (Rh-).
- In general, Rh+ blood can be transfused to Rh+ or Rh- individuals, while Rh- blood should only be given to Rh- recipients to avoid potential complications.
In conclusion, individuals with blood type O are the universal donors because their blood does not have the A or B antigens, making it compatible with all other blood types. However, it is always important to consider other factors such as the Rh factor when matching blood for transfusions.
Biology: Topic-wise Test- 8 - Question 70
When a homozygous red grain wheat is crossed with a white and the offsprings are selfed, howmany offsprings resemble the parents genotypically
Biology: Topic-wise Test- 8 - Question 71
The grain colour of wheat was quantitatively analysed by
Detailed Solution for Biology: Topic-wise Test- 8 - Question 71
Analysis of Grain Colour of Wheat
The grain colour of wheat was quantitatively analysed by several scientists. Among them, the correct answer is option C, Nilsson-Ehle. Here is a detailed explanation:
A: East
- Option A, East, is not the correct answer for the quantitative analysis of grain colour of wheat.
B: de V ries
- Option B, de V ries, is not the correct answer for the quantitative analysis of grain colour of wheat.
C: Nilsson-Ehle
- Option C, Nilsson-Ehle, is the correct answer for the quantitative analysis of grain colour of wheat.
- Nilsson-Ehle was a Swedish plant breeder and geneticist who extensively studied the genetics of wheat.
- He conducted experiments and developed methods to quantitatively analyze grain colour in wheat varieties.
- His work led to the understanding of the genetic basis of grain colour and its inheritance patterns in wheat.
D: Landsteiner
- Option D, Landsteiner, is not the correct answer for the quantitative analysis of grain colour of wheat.
In conclusion, the quantitative analysis of grain colour of wheat was conducted by Nilsson-Ehle (option C).
Biology: Topic-wise Test- 8 - Question 72
Mental retardation related to sex chromosome abnormality is due to
Detailed Solution for Biology: Topic-wise Test- 8 - Question 72
Mental retardation related to sex chromosome abnormality is due to:
There are several sex chromosome abnormalities that can lead to mental retardation. However, the specific cause of mental retardation varies depending on the type of abnormality. In this case, the correct answer is A: increase in X-complement 2. Here's a detailed explanation:
1. X-complement abnormalities:
- The sex chromosomes in humans consist of two types: X and Y. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
- Abnormalities in the number or structure of the sex chromosomes can lead to various developmental disorders, including mental retardation.
- One type of genetic abnormality is an increase in the number of X chromosomes, such as X-complement 2 (XXX). This is known as Triple X syndrome.
- Triple X syndrome occurs in females who have an additional X chromosome, resulting in a total of three X chromosomes instead of the usual two.
- This extra X chromosome can disrupt normal brain development and function, leading to intellectual disabilities or mental retardation.
2. Effects of an increased X-complement:
- The presence of an extra X chromosome can cause physical and cognitive symptoms that vary in severity from person to person.
- Intellectual disabilities are a common feature of Triple X syndrome, with affected individuals typically having mild to moderate mental retardation.
- Other possible symptoms may include learning difficulties, delayed speech and language development, attention deficit hyperactivity disorder (ADHD), and social or behavioral issues.
In conclusion, mental retardation related to sex chromosome abnormality is specifically caused by an increase in X-complement, such as X-complement 2 (XXX) in the case of Triple X syndrome. This abnormality disrupts normal brain development and function, leading to intellectual disabilities.
Biology: Topic-wise Test- 8 - Question 73
If two pairs of chromosomes can recombine in four possible ways, then five pairs of chromosomes would combine in
Detailed Solution for Biology: Topic-wise Test- 8 - Question 73
For 2 pairs it has 4 ways... i.e for 1 pair it has 2 ways . it means that for every pair ,the no. of ways is doubling.... then for 5 pairs...I.e.n=5.. 2^n=2^5=32 ways.......
Biology: Topic-wise Test- 8 - Question 74
A person with Klinefelter’s syndrome has
Detailed Solution for Biology: Topic-wise Test- 8 - Question 74
Klinefelter’s syndrome and Chromosome Count
Introduction:
Klinefelter's syndrome is a chromosomal condition that occurs in males. It is characterized by the presence of an extra X chromosome, resulting in a total of 47 chromosomes instead of the usual 46.
Explanation:
Here is a detailed explanation of why the answer is A - 47 chromosomes for a person with Klinefelter's syndrome:
1. Normal chromosome count: In humans, the normal chromosome count is 46, with 23 pairs of chromosomes. These pairs consist of one sex chromosome pair (XX for females and XY for males) and 22 pairs of autosomes.
2. Extra X chromosome: In individuals with Klinefelter's syndrome, there is an additional X chromosome, resulting in a total of 47 chromosomes. Instead of the usual XY combination, they have XXY.
3. Cause of Klinefelter's syndrome: Klinefelter's syndrome occurs due to a random error during the formation of reproductive cells (sperm or egg) in one of the parents. It is not related to any behavioral or environmental factors.
4. Physical and developmental characteristics: Individuals with Klinefelter's syndrome may exhibit various physical and developmental characteristics, such as tall stature, decreased facial and body hair, gynecomastia (enlarged breasts), small testes, and infertility.
5. Diagnosis and management: Klinefelter's syndrome can be diagnosed through genetic testing, typically conducted when there are signs and symptoms present. Early intervention and management can help address specific needs and improve quality of life.
In conclusion, a person with Klinefelter's syndrome has 47 chromosomes instead of the usual 46, with an extra X chromosome. This chromosomal abnormality leads to specific physical and developmental characteristics associated with the syndrome.
Biology: Topic-wise Test- 8 - Question 75
During meiosis I homologous chromosomes of one pair switch their positions without affecting the position of another pair. This is known as
Detailed Solution for Biology: Topic-wise Test- 8 - Question 75
Explanation:
The correct answer is D: independent assortment. Here's a detailed explanation:
What is meiosis I?
Meiosis I is the first division of meiosis, a specialized type of cell division that reduces the chromosome number by half. It involves the separation of homologous chromosomes, which are pairs of chromosomes that carry the same genes.
What happens during meiosis I?
During meiosis I, several important events take place:
1. Prophase I: Homologous chromosomes pair up and exchange genetic material through a process called crossing over.
2. Metaphase I: Homologous chromosome pairs align along the equatorial plane of the cell.
3. Anaphase I: Homologous chromosomes separate and move towards opposite poles of the cell.
4. Telophase I: Two cells are formed, each containing one complete set of chromosomes.
What is independent assortment?
Independent assortment refers to the random orientation of homologous chromosomes during metaphase I. In other words, the arrangement of one pair of homologous chromosomes does not affect the arrangement of another pair. This occurs due to the random alignment and separation of chromosomes during meiosis I.
Why is it called independent assortment?
It is called independent assortment because the segregation of one pair of homologous chromosomes is independent of the segregation of another pair. The orientation of each pair of homologous chromosomes in metaphase I is independent of the other pairs, leading to a variety of possible combinations of chromosomes in the resulting gametes.
Key Points:
- Meiosis I is the first division of meiosis, which reduces the chromosome number by half.
- During meiosis I, homologous chromosomes pair up, exchange genetic material, and separate.
- Independent assortment refers to the random orientation of homologous chromosomes during metaphase I.
- Independent assortment results in a variety of possible combinations of chromosomes in the resulting gametes.
Biology: Topic-wise Test- 8 - Question 76
The transforming substance of pneumococcus in Griffith’s experiment was
Detailed Solution for Biology: Topic-wise Test- 8 - Question 76
Griffith's Experiment:
Griffith's experiment, conducted by Frederick Griffith in 1928, aimed to investigate the transforming substance of pneumococcus bacteria. He used two strains of pneumococcus, a pathogenic (virulent) strain and a non-pathogenic (avirulent) strain.
Experimental Procedure:
1. Griffith injected mice with the pathogenic strain of pneumococcus, causing the mice to die. This strain had a polysaccharide capsule that protected it from the immune system.
2. He then injected mice with the non-pathogenic strain, which did not have the capsule and did not cause any harm.
3. Griffith heat-killed the pathogenic strain, making it unable to infect the mice. He injected this heat-killed strain into mice and observed that they survived.
4. Next, Griffith mixed the heat-killed pathogenic strain with the live non-pathogenic strain and injected it into mice.
Observations:
Griffith made two key observations:
1. The mice injected with the mixture of heat-killed pathogenic and live non-pathogenic strains died.
2. Upon examination of the mice's blood, Griffith found live pathogenic bacteria.
Conclusion:
Based on his observations, Griffith concluded that something from the heat-killed pathogenic strain had transformed the non-pathogenic strain into a virulent form. He called this phenomenon "transformation."
Nature of the Transforming Substance:
1. Initially, it was believed that the transforming substance was a protein or polysaccharide since these components were known to be present in bacteria.
2. However, further research by Avery, MacLeod, and McCarty in 1944 revealed that DNA was the transforming substance.
Proof of DNA as the Transforming Substance:
1. Avery, MacLeod, and McCarty extracted various components from the heat-killed pathogenic strain and treated the mixture with different enzymes to destroy proteins, RNA, and DNA.
2. They found that only when DNA was destroyed, the transforming ability was lost.
3. When DNA was intact, the non-pathogenic bacteria were transformed into pathogenic bacteria.
4. This experiment provided strong evidence that DNA was responsible for the transformation observed by Griffith.
Therefore, the transforming substance in Griffith's experiment was identified as DNA.
Biology: Topic-wise Test- 8 - Question 77
Genetic information in DNA is encoded in
Detailed Solution for Biology: Topic-wise Test- 8 - Question 77
Genetic information in DNA is encoded in:
- Sequences of bases: DNA is made up of a sequence of nucleotide bases, including adenine (A), thymine (T), cytosine (C), and guanine (G). The order of these bases within the DNA molecule determines the genetic information encoded in the DNA.
- Base pairs: The bases in DNA form complementary pairs through hydrogen bonding, with adenine always pairing with thymine, and cytosine always pairing with guanine. The specific arrangement of these base pairs along the DNA molecule carries the genetic code.
- The backbone: The backbone of DNA consists of a sugar-phosphate backbone, with nucleotide bases attached to the sugar molecule. While the backbone provides structural support to the DNA molecule, it does not directly encode genetic information.
- The major groove: The major and minor grooves are the spaces between the two strands of the DNA double helix. Although proteins involved in DNA binding can recognize specific sequences within the major groove, the information itself is not encoded within the groove.
Therefore, the genetic information in DNA is primarily encoded in the sequences of bases, specifically the order and arrangement of the four nucleotide bases along the DNA molecule.
Biology: Topic-wise Test- 8 - Question 78
In the experiment of Meselson and Stahl, the heavy DNA was allowed to undergo two rounds of replication in medium. The isolated DNA would show
Biology: Topic-wise Test- 8 - Question 79

Uncoiling of the double helix is done by

Detailed Solution for Biology: Topic-wise Test- 8 - Question 79

Topoisomerases catalyze and guide the unknotting or unlinking of DNA by creating transient breaks in the DNA using a conserved tyrosine as the catalytic residue. The insertion of (viral) DNA into chromosomes and other forms of recombination can also require the action of topoisomerases.

Biology: Topic-wise Test- 8 - Question 80
If the template strand of DNA has the sequence ATGCCATGCC, what would be the sequence of RNA?
Detailed Solution for Biology: Topic-wise Test- 8 - Question 80
In RNA, Uracil is present and thymine is absent so UACGGUACGG...
Biology: Topic-wise Test- 8 - Question 81