Test: Botany Mock Test - 2 - NEET MCQ

Answer: B. Anaphase-I

Explanation:
During meiosis, homologous chromosomes separate during Anaphase-I. Meiosis is a two-step process, consisting of Meiosis I and Meiosis II.

Meiosis I:
- Prophase-I: Chromosomes condense, homologous chromosomes pair up, and crossing over occurs between non-sister chromatids.
- Metaphase-I: Homologous chromosome pairs align at the equatorial plate.
- Anaphase-I: Homologous chromosomes separate and move towards opposite poles of the cell.
- This is the phase where the answer lies, as homologous chromosomes separate during this phase.
- Telophase-I: Chromosomes reach the poles of the cell, nuclear envelope reforms, and the cell divides into two daughter cells.

Meiosis II:
- Prophase-II: Chromosomes condense again, and the nuclear envelope breaks down.
- Metaphase-II: Individual chromosomes align at the equatorial plate.
- Anaphase-II: Sister chromatids separate and move towards opposite poles of the cell.
- Telophase-II: Chromatids reach the poles of the cell, nuclear envelope reforms, and the cells divide, resulting in four genetically unique haploid cells.

Explanation: The correct answer is B: Nucleolus and nuclear envelope. During mitosis and meiosis, the cellular structure that always disappears is the nucleolus and nuclear envelope. This is because these structures need to break down to allow the chromosomes to separate and be distributed to the new cells formed during cell division. Here's a brief overview of their roles and what happens during cell division: Nucleolus: - It is a small, dense structure within the nucleus of a cell. - Its primary function is to produce ribosomes, which are essential for protein synthesis. - During the prophase of mitosis and meiosis, the nucleolus disassembles, and its components are dispersed throughout the cell. Nuclear envelope: - It is a double membrane that surrounds the nucleus of a cell. - It separates the genetic material within the nucleus from the cytoplasm of the cell. - During the prophase of mitosis and meiosis, the nuclear envelope breaks down, allowing the chromosomes to be accessed by the spindle fibers that will separate them during cell division. In summary, the nucleolus and nuclear envelope are cellular structures that always disappear during mitosis and meiosis to facilitate the process of cell division.

Explanation: During the pachytene stage of meiosis, the chromosomes appear as four stranded structures. This stage is part of the prophase I of meiosis, and it is characterized by the following features: - Synapsis: Homologous chromosomes (chromosomes that have the same genes but can have different alleles) pair up and come close together, forming a synaptonemal complex. This process is called synapsis. - Tetrad formation: Each pair of homologous chromosomes consists of two sister chromatids, making a total of four chromatids in the complex. These four chromatids together are called a tetrad or bivalent, giving the appearance of a four-stranded structure. - Crossing over: During pachytene, genetic material is exchanged between non-sister chromatids of homologous chromosomes. This process is called recombination or crossing over, and it leads to the formation of chiasmata (points of contact between chromatids where the exchange of genetic material occurs). - Genetic variation: The crossing over of genetic material during pachytene contributes to genetic variation within the offspring, as it allows for the mixing of parental alleles. In summary, during the pachytene stage, chromosomes appear as four-stranded structures due to the pairing of homologous chromosomes and the formation of tetrads. These tetrads are essential for genetic recombination and the generation of genetic variation in offspring.

Answer: B:

nicotine

Explanation: • Nicotine: Nicotine is a naturally occurring alkaloid found in the leaves of the tobacco plant (Nicotiana tabacum). It is the primary psychoactive ingredient in tobacco products, responsible for the addictive qualities of these products. • Aspirin (not in tobacco leaves): Aspirin (acetylsalicylic acid) is a nonsteroidal anti-inflammatory drug (NSAID) used for pain relief and to reduce inflammation. It is not found in tobacco leaves. • Colchicine (not in tobacco leaves): Colchicine is an alkaloid derived from the autumn crocus (Colchicum autumnale) plant. It is used to treat gout and certain other inflammatory conditions but is not present in tobacco leaves. • Capsaicin (not in tobacco leaves): Capsaicin is the active component in chili peppers (Capsicum genus), responsible for their spicy heat. It is not found in tobacco leaves.

• All the statements are correct about epidermal tissue system. It is the outer protective layer of cells of a plant, which may be thickened by a cuticle. It consists of epidermis and epidermal outgrowth.
• Epidermis is the superficial layer covering the entire surface of the primary plant body. All the epidermal cells are living (parenchymatous) and contain vacuolated protoplasm. Stomata arc the structures present in the epidermis of leaves. Epidermal outgrowths arc of two kinds- trichomcs and emergences.

Answer: C:

UAG/UAA

Explanation: - A nonsense/termination codon is a specific sequence of three nucleotides in an mRNA molecule that signals the end of protein synthesis. - These codons do not code for any amino acids and are also known as stop codons. - There are three nonsense/termination codons in the genetic code: UAG (amber), UAA (ochre), and UGA (opal). -

UAG/UAA

(Option C) are two of the three termination codons that signal the end of protein synthesis. -

UUU

(Option A) codes for the amino acid phenylalanine. -

GCG

(Option B) codes for the amino acid alanine. -

CCC

(Option D) codes for the amino acid proline.

Ovary wall forms pericarp after fertilization. Pericarp is the tissue that develops from the ovary wall of the flower and surrounds the seeds. The pericarp is typically made up of three distinct layers: the epicarp (outermost layer); the mesocarp (middle layer); and the endocarp (inner layer surrounding the ovary or the seeds). In a citrus fruit, the epicarp and mesocarp make up the peel.

Exine of pollen grain is made up of highly resistant fatty substance called sporopollenin, which is not degraded by any enzyme. It is not affected by high temperature, strong acid or strong alkali. Because of the sporopollenin, pollen grains are well preserved as microfossils.

Answer: A Explanation: - Blood group inheritance is determined by the ABO gene, which has three alleles: A, B, and O. These alleles are inherited from both parents, leading to four possible blood groups: A, B, AB, and O. - The O blood group results from inheriting two O alleles, one from each parent (OO genotype). - In the given options: 1. AB and AB/O: A child with blood group O cannot have parents with blood groups AB and AB/O because parents with these blood groups will always pass on either A or B alleles to their offspring. There is no possibility of passing on an O allele, which is necessary for the child to have blood group O. 2. A and B: A child with blood group O can have parents with blood groups A and B if both parents have AO and BO genotypes. In this case, there is a 25% probability that the child will inherit an O allele from each parent, resulting in the OO genotype and blood group O. 3. B and B: A child with blood group O can have parents with blood groups B and B if both parents have BO genotypes. In this case, there is a 25% probability that the child will inherit an O allele from each parent, resulting in the OO genotype and blood group O. 4. O and O: A child with blood group O will always have parents with blood groups O and O because both parents must have OO genotypes to ensure the child inherits an O allele from each parent. Thus, the correct answer is A (AB and AB/O), as a child with blood group O cannot have parents with those blood groups.

Dioecious plants are those plants in which male flowers and female flowers are borne on different plants. Therefore, they prevent both autogamy and geitonogamy.

Explanation of ATP Production in Photosynthesis: - Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose or other sugars. - ATP (adenosine triphosphate) is an energy-carrying molecule used to store and release energy in cells. Photophosphorylation: - Photophosphorylation is the process of ATP production in photosynthesis. - It involves the transfer of a phosphate group from a high-energy donor molecule to ADP (adenosine diphosphate) to form ATP. - This process is driven by the light energy captured by photosynthetic pigments, such as chlorophyll. Steps in Photophosphorylation: 1. Light absorption: Photosynthetic pigments (e.g., chlorophyll) absorb light energy, which excites their electrons to a higher energy level. 2. Electron transport: The excited electrons are transferred through a series of carrier molecules (electron transport chain) in the thylakoid membrane of the chloroplast, releasing energy at each step. 3. Chemiosmosis: The energy released during electron transport is used to pump hydrogen ions (protons) across the thylakoid membrane, creating a proton gradient. 4. ATP synthesis: The proton gradient drives the synthesis of ATP through a process called chemiosmotic phosphorylation. As protons flow back across the membrane through ATP synthase, they provide the energy needed for ADP to gain a phosphate group, forming ATP. In summary, the ATP production in photosynthesis is called photophosphorylation, which involves the conversion of light energy into chemical energy (ATP) through a series of steps involving light absorption, electron transport, chemiosmosis, and ATP synthesis.

The essential process connected with photosynthesis is: A: Photolysis of water Explanation: Photosynthesis is a process used by plants, algae, and some bacteria to convert light energy into chemical energy in the form of glucose or other sugars. There are several processes involved in photosynthesis, and one of the crucial steps is the photolysis of water. - Photolysis of water: Also known as the light-dependent reaction or water-splitting reaction, this process occurs in the thylakoid membrane of the chloroplasts. It involves the absorption of light by photosystem II, which excites electrons and leads to the splitting of water molecules. The breakdown of water produces oxygen gas (O2), which is released as a byproduct, as well as hydrogen ions (H+) and electrons that are used in the next steps of photosynthesis. - Importance of photolysis: The photolysis of water is essential for photosynthesis because it provides the necessary electrons and protons for the production of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). Both ATP and NADPH are essential energy carriers that are required for the light-independent reactions, also known as the Calvin-Benson cycle, during which carbon dioxide is fixed, and glucose is synthesized. The other options mentioned (B, C, and D) are also related to photosynthesis, but they are not as essential as the photolysis of water: - B: Synthesis of glucose: This is the ultimate goal of photosynthesis, but it is not an essential process directly connected to the light-dependent reactions. Glucose synthesis occurs during the light-independent reactions (Calvin-Benson cycle). - C: Breakdown of glucose: This is related to cellular respiration rather than photosynthesis. The breakdown of glucose provides energy for the cell, but it is not an essential process directly connected to photosynthesis. - D: Photophosphorylation: This is the process by which ATP is produced during the light-dependent reactions of photosynthesis. While it is an essential process for producing the energy needed for the light-independent reactions, it is not as directly connected to photosynthesis as the photolysis of water.

ATP to ADP Conversion - The conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) is a process that occurs in cells and plays a crucial role in energy production. - During this process, the following occurs: * Energy Release: ATP, which contains three phosphate groups, loses one of its phosphate groups to become ADP. This process of breaking the bond between the second and third phosphate groups releases energy. Therefore, the correct answer is B: Energy. * Cellular Functions: The energy released during the conversion of ATP to ADP is used by the cell for various functions, such as muscle contraction, protein synthesis, and nerve impulse transmission. * Regeneration of ATP: After losing a phosphate group, ADP can be converted back to ATP through cellular respiration, allowing the cell to continue producing and using energy. In summary, the conversion of ATP to ADP is an essential process in cellular energy production, resulting in the release of energy for various cellular functions.

Least Effective in Photosynthesis: - Answer: d. Green light Explanation: - Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose or other sugars. - In photosynthesis, pigments within chlorophyll absorb light energy, which is then used to convert carbon dioxide and water into glucose. - There are several pigments involved in photosynthesis, but the most important one is chlorophyll. Chlorophyll primarily absorbs red and blue light, and reflects green light. - Green light: Since green light is mostly reflected and not absorbed by chlorophyll, it is the least effective in photosynthesis. - Blue light: Blue light is efficiently absorbed by chlorophyll and is very effective in driving photosynthesis. - Red light: Red light is also efficiently absorbed by chlorophyll and is effective in driving photosynthesis. - Sunlight: Sunlight contains a full spectrum of colors, including red, blue, and green light. Since red and blue light are the most effective in photosynthesis, sunlight is an excellent source of energy for this process.

Answer: C - John Ray Explanation: - John Ray (1627-1705) was an English naturalist and botanist who made significant contributions to the field of taxonomy. - Ray was the first to provide a clear definition of the term "species." - He defined species as a group of organisms that share common characteristics and can interbreed to produce fertile offspring. - This definition laid the foundation for the modern concept of species and helped pave the way for the development of taxonomy and the classification of living organisms. - Ray's work influenced many naturalists and biologists, including Linnaeus, who later developed the binomial naming system that is still used today.

Unisexuallity of flowers prevents autogamy but not geitonogamy because autogamy is the transfer of pollen grains from anther to stigma of same flower and geitonogamy is the fertilization of a flower by pollen from another flower on the same plant. Therefore, geitonogamy occurs between bisexual flowers or unisexual flowers of the same plant.

Vascular cambium is located between the xylem and the phloem in the stem and roots of a vascular plant, and is the source of both the secondary xylem grow'th (inwards, towards the pith) and the secondary phloem growth (outwards).

The assertion is true as dicotyledonous plants typically have leaves with reticulate venation, characterized by a complex network of veins. However, the reason is true but does not correctly explain the assertion. Reticulate venation is more related to the structural support and the evolutionary adaptation of dicots to their environment rather than solely to the efficiency of nutrient distribution.

The assertion is true as actinomorphic flowers do exhibit radial symmetry, allowing them to be divided into two equal halves along any radial plane. The reason is also true; however, it does not directly explain why actinomorphic flowers can be divided in such a manner. Instead, it provides an ecological advantage of radial symmetry, which is attracting a broader range of pollinators.

The aleurone layer in monocotyledonous seeds plays a crucial role in food storage. It is a protein-rich layer that surrounds the endosperm, providing essential nutrients for the germinating seed.

Single megaspore mother cell (MMC) with dense cytoplasm and a prominent nucleus gets differentiated from nucellus near the micropylar region. This megaspore mother cell (MMC) undergoes meiosis to form ‘4’ haploid cells (called megaspores) and the process of formation is known as megasporogenesis.

Relative growth rate is the measure of the ability of the plant to produce new plant material.
Growth = 19 – 5 = 14 cm
Period = 7 days
Growth rate = 14/7 = 2 cm/day
Relative growth rate = 2/5 × 100 = 40%

The pulvinus is a swollen leaf base found in some leguminous plants, such as peas and beans. It plays a significant role in leaf movement, allowing leaves to adjust their position in response to environmental stimuli, enhancing photosynthesis and minimizing damage.

Taxa is a plural form of taxon. Taxon is a grouping of organisms of any level in hierarchial classification which is based on some common characteristics. It represents real biological objects placed in any category while category itself is an abstract term.

Megaspore mother cell (MMC) undergoes meiosis to form four haploid cells (called megaspores) and the process of formation is known as megasporogenesis. The MMC undergoes meiotic division results in the production of four megaspores 100 functional megaspores are produced by 100 MMC, since three out of four megaspores degenerate in each case.

Sieve tubes are the conducting elements of phloem (a vascular tissue which conducts organic food in plant body) which are elongated tubular channels formed by end to end union of numerous cells. The septa between individual sieve tube cells or sieve elements are bulged out. They are called sieve plates possessing a number of perforations (sieve pores or sieve pits) and helps in conduction of food.

Bryophytes have multicellular jacketed sex organs to protect gametes against drying effects of air and retention of zygote inside archegonium to provide nourishment to developing embryo.

The mesophyll, located within the leaves, is the primary site of photosynthesis in most plants. This tissue is rich in chloroplasts, which contain chlorophyll, the pigment responsible for capturing light energy to synthesize sugars from carbon dioxide and water.

Development includes all changes that an organism goes through during its life cycle from germination of the seed to senescence. The correct sequence of the developmental process in a plant cell is:
Cell division → Differentiation → Maturation → Senescence
Cell division involves plasmatic growth.
Differentiation is a process in which cells undergo few to major structural changes both in their cell walls and protoplasm. Maturation is the process that a living thing goes through as it ages and becomes ripe or fully developed. Senescence is the stage in the life history of an individual when the rate of metabolic activities declines that leads to ageing and then eventually death.

Auxin is a plant hormone known for its role in promoting cell elongation, especially in the stem. It regulates various aspects of growth and development by facilitating the stretching of cell walls, allowing cells to expand.