Test: Botany Mock Test - 3 - NEET MCQ

Auxins specifically stimulate root initiation on stem cuttings, promoting the formation of new roots and thereby facilitating vegetative propagation.

Gibberellin is known for its role in promoting stem elongation and breaking seed dormancy by stimulating the synthesis of enzymes that mobilize food reserves in the seed, facilitating germination.

Chlorophyll's primary role in photosynthesis is to absorb sunlight and convert it into chemical energy. This process is crucial for driving the light-dependent reactions, where the absorbed light energy is used to produce ATP and NADPH, which are then utilized in the Calvin cycle to fix carbon dioxide into carbohydrates.

Microsporogenesis, the process of forming microspores from a pollen mother cell (PMC), begins during Prophase I of meiosis. This is when the PMC undergoes meiotic division to eventually produce four haploid microspores.

Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme responsible for fixing carbon dioxide in the Calvin cycle. It catalyzes the first step of the cycle, the carboxylation of ribulose-1,5-bisphosphate, which is a critical step in the synthesis of organic molecules from carbon dioxide.

Chasmogamous flowers are designed to facilitate cross-pollination by opening and exposing their reproductive parts, whereas cleistogamous flowers remain closed, ensuring self-pollination. This strategy allows plants to reproduce even under less favorable conditions for pollinator activity.

The filiform apparatus, found at the micropylar end of the synergid cells in the embryo sac, plays a crucial role in guiding the pollen tube towards the synergid. This structure is composed of cellular extensions that increase the surface area for the reception of the pollen tube, ensuring that it reaches its target accurately for successful fertilisation. This mechanism is vital for the pollen tube to deliver the male gametes to the egg cell, facilitating the process of fertilisation.

The vegetative cell in a pollen grain is larger and provides nutrition to the smaller generative cell. The generative cell, in turn, divides to form two sperm cells, one of which will fertilize the egg cell during the process of double fertilisation.

The Calvin cycle primarily produces glucose, utilizing ATP and NADPH generated during the light reactions of photosynthesis. This cycle is a series of enzyme-assisted chemical reactions that convert carbon dioxide and other compounds into glucose. Interesting fact: The Calvin cycle is also known as the dark reactions, although it does not require darkness to occur but rather the products of the light reactions.

Abscisic acid is known as the stress hormone because it plays a key role in enabling plants to cope with stress conditions such as drought and salinity by inducing stomatal closure and seed dormancy.

Ethephon is the compound used to supply ethylene. It is readily absorbed in aqueous solution and transported within the plant and it releases ethylene slowly. Ethephon hastens fruit ripening in tomatoes and apples. It accelerates abscission of flowers and fruits in cotton, cherry, walnut, etc.

Carbon dioxide (CO₂) is used as the carbon source in photosynthesis. Plants absorb CO₂ from the atmosphere through their leaves and, using the energy from sunlight, convert it into organic compounds like glucose in the process of carbon fixation during the Calvin cycle.

Ethylene is unique because it is the only gaseous plant hormone, playing key roles in processes such as fruit ripening, abscission of leaves and fruits, and the response to stress conditions.

In the process of photosynthesis, the oxygen atoms found in glucose come from carbon dioxide. During the Calvin cycle, carbon dioxide is fixed and reduced to produce glucose, incorporating its oxygen atoms into the sugar molecule.

Engelmann's experiment demonstrated that photosynthesis is more effective in red and blue light. He observed that aerobic bacteria congregated in these regions of the spectrum, indicating a higher rate of oxygen production by the alga due to more effective photosynthesis, thus attracting the bacteria.

Auxins, gibberellins, and cytokinins can indeed act synergistically in promoting plant growth. These hormones work together to regulate various aspects of growth and development, such as cell division, elongation, and differentiation. This synergy allows plants to adapt their growth in response to environmental conditions. An interesting fact is that while these hormones can promote growth, they can also interact with other hormones like abscisic acid and ethylene, which can inhibit growth under certain conditions, demonstrating the complex regulation of plant development.

Abscisic acid (ABA) primarily functions as a stress hormone, playing a crucial role in inducing seed dormancy and enabling seeds to withstand desiccation and other unfavorable conditions.

The mitochondrion is not a component of a chloroplast. Chloroplasts, the site of photosynthesis in plant cells, contain thylakoids, stroma, and grana as their main components. Mitochondria are separate organelles responsible for cellular respiration. Interesting fact: While chloroplasts convert light energy into chemical energy, mitochondria perform the opposite function, breaking down chemical energy into a form that the cell can use.

The primary acceptor of electrons from water in photosynthesis is chlorophyll a in Photosystem II. When water is split during the light-dependent reactions, electrons are transferred to chlorophyll a in Photosystem II, initiating the electron transport chain that leads to the production of ATP and NADPH.

ATP is a product of the light-dependent reactions of photosynthesis. These reactions, which occur in the thylakoid membranes of chloroplasts, use light energy to produce ATP and NADPH, which are then used in the Calvin cycle to synthesize glucose from carbon dioxide.

Apical dominance, where the main central stem of the plant grows more strongly than the side stems, is primarily regulated by auxins. Auxins produced in the apical bud suppress the growth of lateral buds.

Glycolysis is not a phase of photosynthesis. It is a metabolic pathway that occurs in the cytoplasm of cells, where glucose is broken down into pyruvate, producing ATP and NADH. It is part of cellular respiration, not photosynthesis, which consists of light-dependent reactions, the Calvin cycle, and carbon fixation.

Cytokinins are known for delaying leaf senescence, promoting lateral bud growth, and stimulating cell division, but they do not directly induce root elongation. Instead, cytokinins primarily affect above-ground parts of the plant, such as stems and leaves.

Glucose is not a product of the light reactions of photosynthesis. It is produced in the Calvin cycle, which uses ATP and NADPH generated during the light reactions to fix carbon dioxide into glucose.

Gibberellin is involved in the positive regulation of seed germination, promoting the breakdown of starch into glucose, which provides energy for the growing embryo.

The Calvin cycle takes place in the stroma of the chloroplasts. This is where the ATP and NADPH produced in the light-dependent reactions are used to fix carbon dioxide into organic molecules like glucose.

Wind-pollinated plants typically have small, inconspicuous flowers that do not need to attract pollinators. Therefore, brightly colored petals, which are meant to attract animal pollinators, are not a feature of wind-pollinated plants.

Correct answer is : Auxin

The main function of the stomata in leaves is to release oxygen and take in carbon dioxide. Stomata are small openings on the underside of leaves that allow gases to be exchanged between the plant and its environment, facilitating photosynthesis and respiration.

The light-dependent reactions of photosynthesis occur in the thylakoid membranes of the chloroplasts and are responsible for producing ATP and NADPH. These molecules provide the energy and reducing power, respectively, for the Calvin cycle, where carbon dioxide is fixed into glucose.