Test: Plant Physiology - SSC CGL MCQ

The primary purpose of photosynthesis in plants is to convert light energy into chemical energy. This process is essential for plants to produce food (carbohydrates) using carbon dioxide (CO2) and water in the presence of sunlight and chlorophyll. Through photosynthesis, light energy is transformed into chemical energy stored in the form of ATP and NADPH, enabling the synthesis of carbohydrates like glucose.

Green plants can perform photosynthesis due to the presence of chlorophyll-a and chlorophyll-b, along with other accessory pigments. These pigments play a crucial role in capturing light energy and converting it into chemical energy stored in organic compounds, such as carbohydrates. Chlorophyll-a and chlorophyll-b are key pigments responsible for the absorption of light during photosynthesis.

ATP and NADPH in photosynthesis play a vital role in storing and transferring energy. These molecules are produced during the light-dependent reactions of photosynthesis and carry the energy needed to drive the synthesis of carbohydrates like glucose. ATP and NADPH act as energy carriers, facilitating the conversion of light energy into chemical energy that can be used in various biochemical processes within the plant.

In cellular respiration, energy is released through the breakdown of food produced during photosynthesis. This energy is crucial for plants as it is utilized to synthesize other necessary molecules vital for their growth, development, and overall functioning.

Xylem tissues in plants are responsible for transporting water and minerals from the roots to the leaves. This transportation network ensures that essential nutrients and water are efficiently distributed throughout the plant, supporting its various physiological processes.

Plants excrete gaseous waste products, such as oxygen and carbon dioxide, by releasing them through specialized structures called stomata. Stomata are small pores located on the surface of leaves that allow for the exchange of gases between the plant and its environment, facilitating processes like photosynthesis and respiration.

Transpiration in plants primarily serves the function of facilitating the transport of water and essential nutrients throughout the plant. This process helps in maintaining the plant's hydration, cooling the plant, and aiding in the movement of minerals from the soil to various parts of the plant. By releasing water vapor through the stomata, transpiration creates a pulling force that allows water and nutrients to move up through the plant's vascular system.

Carbon and Oxygen are classified as macroelements crucial for plant growth and development. These elements are fundamental components of various organic molecules within plants, playing essential roles in processes such as photosynthesis, respiration, and the formation of structural components like carbohydrates and proteins.

Biological nitrogen fixation is the crucial process in nitrogen metabolism that takes place in the roots of leguminous plants. Through a symbiotic relationship with Rhizobium bacteria, these plants are able to convert atmospheric nitrogen gas into a form that is usable by plants, primarily through the formation of nitrogen-fixing nodules on their roots. This process is essential for ensuring an adequate supply of nitrogen for plant growth and development.

The process where a new plant is formed by the germination of a seed after being in a dormant stage is called seed germination. During this process, the seed begins to sprout and grow into a seedling. Seed germination is a crucial stage in the plant life cycle where the embryo inside the seed starts to grow, leading to the development of a new plant.

Growth in plants is regarded as the irreversible permanent increase in both size and biomass. It is a fundamental process in plant development where cells divide and expand, leading to the overall increase in the plant's size and biomass. Plant growth is influenced by various factors, including plant hormones and environmental conditions, and plays a vital role in the development and reproduction of plants.

Long Day Plants (LDP) are plants that require light exposure exceeding a specific critical duration for flowering. Examples of Long Day Plants include spinach and sugar beet. These plants initiate flowering when exposed to longer periods of light, which triggers the physiological processes leading to the development of flowers and seeds.

Carbohydrates like glucose are crucial products of photosynthesis for plants because they serve as a primary source of energy. Plants utilize glucose for various metabolic processes, growth, and development. Additionally, glucose can be stored as starch for later use, providing plants with a readily available energy reserve that can be mobilized when needed for activities such as growth, reproduction, and response to environmental stimuli.

Adenosine Triphosphate (ATP) serves as the energy currency of the cell, providing the necessary energy for various cellular functions in plants. The hydrolysis of one ATP molecule releases about 7.6 kcal (31.8 kJ) of energy, which is indispensable for powering processes like active transport, biosynthesis, and cellular signaling.

Nitrifying bacteria such as Nitrosomonas play a crucial role in nitrogen metabolism by converting ammonium (NH4+) into nitrates (NO3-) and nitrites (NO2-). This process is important for transforming nitrogen into forms that plants can readily absorb and utilize for various physiological functions, ultimately contributing to the overall nutrient cycling in ecosystems.