Biology: CUET Mock Test - 8 - CUET MCQ

An antibody is represented by H₂L₂ formula. Each antibody molecule has four peptide chains, two long chains called heavy or H chains and two short chains called light or L chains.

Key Points

• Grassland and desert are examples of terrestrial ecosystems. These are natural ecosystems found on land.
• Oceans and rivers are not man-made ecosystems; they are natural. The statement (B) is incorrect as it classifies them as man-made.
• Wetland and estuary are indeed examples of aquatic ecosystems, which are natural environments where water plays a significant role in supporting the life forms within them.
• Crop fields and aquariums are not natural ecosystems. They are man-made or artificial ecosystems created and maintained by humans. Therefore, statement (D) is incorrect when it suggests they are natural.

Additional Information

• A natural ecosystem operates independently of human intervention. It includes all living organisms and non-living components interacting as a system in a specific area.
• Man-made or artificial ecosystems, such as crop fields and aquariums, require human intervention for maintenance and often do not possess the self-sustaining balance found in natural ecosystems.

The correct option is (A) (II), (B) (III), (C) (I), (D) (IV).

Key Points

Genetic diversity is illustrated by Rauwolfia vomitoria in different Himalayan ranges. Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species. It serves as a way for populations to adapt to changing environments. Rauwolfia vomitoria showing variation across the Himalayan ranges is a perfect example of genetic diversity. Different environmental conditions across the ranges select for different genetic traits, leading to diversity within the species.

Species diversity is exemplified by Amphibians in Western Ghats. Species diversity is a measure of the variety of species within a region. This includes both the number of species present and their relative abundance. The Western Ghats in India are known for their high levels of species diversity, particularly among amphibians. This region is a biodiversity hotspot, home to a large number of species that are not found anywhere else in the world.

Ecological diversity is shown by Mangroves and Coral reef. Ecological diversity refers to the variations in ecosystems within a geographical location and its overall impact on human existence and the environment. Mangroves and coral reefs are examples of different types of ecosystems, each supporting a unique set of organisms and contributing to the overall ecological diversity of a region. These ecosystems play critical roles in protecting coastlines, supporting fisheries, and storing carbon.

Biodiversity loss is demonstrated by the extinction of the Dodo in Mauritius. Biodiversity loss refers to the reduction or loss of species in a certain habitat. It can be the result of a variety of factors, including habitat destruction, climate change, pollution, and overexploitation. The Dodo, which was native to Mauritius, became extinct in the late 17th century due to human activities. It is often cited as an example of the consequences of human impact on biodiversity.

Conclusion:

Therefore, the correct pairing is: A II: Genetic diversity Rauwolfia vomitoria in different Himalayan ranges B III: Species diversity Amphibians in Western Ghats C I: Ecological diversity Mangroves and Coral reef D IV: Biodiversity loss Dodo in Mauritius

Key Points

Electrostatic precipitators are used in thermal power plants to remove particulate air pollutants. This method utilizes a high-voltage electric field to charge the dust particles in the exhaust gases. Once charged, these particles are attracted to and deposited on collector plates, from where they are periodically removed.

Additional Information

• Catalytic converters are primarily used in automotive exhaust systems to convert harmful gases into less harmful substances but are not typically used for particulate matter removal in industrial settings.
• Scrubbers are devices that use a liquid (often water) to remove pollutants from exhaust gases. They are effective for gas pollutants and some particulates, especially those that are soluble in the scrubbing liquid.
• Filtration involves passing air through filters to physically remove particles. While effective for particulate removal, the type of filters and their maintenance can vary widely in effectiveness and cost.

Concept:

• The founder effect occurs when a small population gets drifted from the parent population and becomes a new population.
• Allele frequency changes as compared to their parent population and thus forming a new population with a new genotype.

Explanation:

• Option 1: Genetic drift is the change in allele frequencies that occurs by chance. It occurs in a small population. The founder effect is a result of genetic drift.
• Option 2: Natural selection is a process by which the organism more fitted to the environment will survive and reproduce to form more of its kind. They are more adapted to their environment.
• Option 3: Genetic recombination is the process of the exchange of DNA fragments between two different chromosomes leading to variation.
• Option 4: Mutation is the change in DNA sequence due to errors in DNA replication, any exposure to mutagens, etc.

So, the correct answer is option 1.

The correct answer is Latex of Papaver somniferum.

• Opioids are drugs that bind to specific opioid receptors in the central nervous system (CNS) and gastrointestinal tract.
• Heroin is commonly called as smack.
• Heroin is a depressent and slows down body functions.
• Source: Morphine is extracted from the Latex of poppy plant Papaver somniferum.
• Heroin or smack is obtained by acetylation of morphine as a white, odourless, bitter, crystalline compound.
• Mode of intake: By snorting and injection.
• Effects: Smack is an effective sedative and painkiller.

Correct answer: 4)

Concept:

• Genetic engineering is the process of manipulating the genetic makeup of an organism.
• Genetic engineering is performed using recombinant DNA technology.
• Insulin can be produced using genetic engineering for large-scale production, for treating Diabetic patients.

Explanation:

• Pro-hormone is the precursor of any specific hormone. Prohormone insulin contains an extra stretch of C-peptide. This is removed from the matured and processed insulin.
• A-peptide and B-peptide chains of insulin were produced separately in E. coli. These peptide chains are then extracted and recombined by the formation of disulfide bridges between them.
• Pro-hormone Insulin needs to be processed for converting into a mature and functional hormone.

So, the correct answer is 4.

The correct answer is option 4.

Concept:

• The embryo sac also called female gametophyte is present in the nucellus of the ovule.
• The embryo sac is formed from a megaspore.

Explanation:

Let us look at the formation of the embryo sac in angiosperms:

• Monosporic development
  • In the majority of flowering plants, only one megaspore is active while the other three degenerate.
  • The embryo sac develops from one functional megaspore hence, this type of development is called monosporic development.
• 8 -nucleate stage/three sequential mitotic divisions
  • The nucleus of the megaspore divides mitotically to form 2 nuclei.
  • These nuclei move in opposite poles to form a 2 nucleate embryo sac.
  • These nuclei further undergo two sequential mitotic divisions to form the first 4 nucleate stages and then 8 nucleate stages.
  • After the 8 nucleate stage, cell walls are laid down leading to the formation of the embryo sac.
  • Six out of 8 nuclei are surrounded by the cell wall.
• Embryo sac
  • Egg apparatus: Three cells are grouped together at the micropylar end and form the egg apparatus.
  • Polar nuclei: The two nuclei called polar nuclei are present below the egg apparatus in the large central cell.
  • Antipodals: Three cells at the chalazal end group together to form antipodals.
  • The embryo sac is 8 nucleate and 7-celled structure.

So, the correct answer is option 4.

Additional Information:

• Bisporic embryo sac
  • In this, two megaspores take part in the formation of the embryo sac.
  • The nucleus of two megaspores undergoes two mitotic divisions to form an 8 nucleate embryo sac.
• Tetrasporic embryo sac
  • In this, all four megaspores take part in the formation of the embryo sac.
  • In the embryo sac, there are four haploid nuclei that are present in the cytoplasm and form a cone megaspore.

(A) Correct: In exponential growth, the population grows at a constant rate without resource limitations.
(B) Correct: Logistic growth is more realistic as it includes resource limitations, leading to a stabilized population size.
(C) Incorrect: Amensalism is when one species is harmed and the other is unaffected, not the other way around.
(D) Incorrect: Resources do not always limit population growth, especially in cases where resources are abundant.
(E) Correct: Resource partitioning allows species to coexist by utilizing resources differently, reducing competition.

(A) Correct: An ecosystem consists of both biotic (living organisms) and abiotic (non-living components) elements.
(B) Incorrect: Primary productivity refers to the production of organic material by producers (plants), not consumers.
(C) Correct: Energy flow in ecosystems is unidirectional, from producers to consumers and decomposers.
(D) Correct: Decomposers break down complex organic matter into simpler inorganic substances, completing the cycle.
(E) Incorrect: The pyramid of energy is always upright, as energy decreases at each trophic level.

Saccharomyces cerevisiae ferments glucose in cereals and fruit juices, producing ethanol, a key component of alcoholic beverages.

During fermentation, yeasts produce ethanol, which is used in alcoholic beverages and as a biofuel.

Penicillin, discovered by Alexander Fleming, was the first antibiotic and marked a significant breakthrough in treating bacterial infections.

Antibiotics are chemicals that kill or inhibit the growth of bacteria, helping treat infections.

Antibiotics have significantly reduced the mortality rates from bacterial infections and made many medical treatments, such as surgeries, much safer.

Key Points

• Chitinase is used for the isolation of genetic material from fungal cells because the cell walls of fungi are primarily composed of chitin, and chitinase helps in breaking down this component.

Additional Information

• Lysozyme is incorrect because it is primarily used to break down the cell walls of bacteria, which are rich in peptidoglycan, not chitin.
• Pepsin is incorrect as it is a digestive enzyme that breaks down proteins in the stomach, not a component of fungal cell walls.
• Cellulase is incorrect because it breaks down cellulose, which is a major component of plant cell walls, not fungal cell walls.

Bioprocess engineering ensures that microbial growth occurs under sterile conditions for the production of biotechnological products like antibiotics and vaccines.

Biotechnology initially involved simple processes like making bread and wine, which utilized fermentation by microorganisms.

Genetic engineering allows scientists to manipulate genetic material to create organisms with desired traits.

Antibiotics and vaccines are produced using biotechnological processes involving microorganisms and genetic manipulation.

Genetic engineering is a core technique that enables the alteration of genetic material to achieve desired outcomes.

IgG and IgA antibodies are responsible for conferring Natural Passive Immunity to the foetus. IgG crosses the placenta during pregnancy and IgA antibodies are present in the yellowish fluid colostrum secreted by mother during the initial days of lactation.

Assimilation is not the function of an antibody. The functions of antibodies include Lysis, Neutralisation, Opsonisation, Precipitation and Agglutination.

IgM is the first antibody which is released during an infection site. IgM is also responsible for the initial activation of B-cells, macrophages and the complement system. It also makes up 7-10% of our total antibodies.

The given structure represents the structure of IgM. It is present in pentameric form and has 10 paratopes (Antigen Binding Sites).

The above given structure is of an antibody molecule. Each antibody molecule has four peptide chains, two small called as light chains and two longer called heavy chains. Both chains are linked by disulfide bonds.

Treponema pallidum is responsible for causing Syphilis. It is a bacterium. It is transmitted through sexual contact or exchange of blood or placenta to the foetus.

Hepatitis-B is caused by Hepatitis B virus (HBV). It is also a venereal disease or a sexually transmitted disease. The virus passes from one person to another by blood, semen or any other body fluids.

The most common site of infection in females suffering from chlamydiasis is the cervix, resulting in cervicitis and production of thick mucus and pus discharge.

Muscular Dystrophy is not a sexually transmitted disease. It is an autosomal dominant Mendelian disorder. Syphilis, Chancroid and Trichomoniasis are sexually transmitted diseases which are caused by Treponema pallidum, Haemophilus ducrei and Trichomonas vaginalis respectively.