CSIR NET Life Science Online Quiz on Plant Physiology: CAM Pathway | Best Online Test Series for CSIR NET Life Science

The CAM pathway involves fixing carbon dioxide at night, which is then stored in the form of organic acids. During the day, the organic acids are broken down to release carbon dioxide for use in photosynthesis.

C4 plants have well-defined bundle sheath cells that are specialized for the C4 pathway, while CAM plants lack well-defined bundle sheath cells.

Both C4 plants and CAM plants have evolved separate biochemical pathways for carbon fixation and the Calvin cycle, which helps them to minimize photorespiration and water loss.

Explanation: CAM plants open their stomata at night to take in carbon dioxide, which is stored in the form of organic acids. During the day, the stomata are closed to conserve water, and the stored organic acids are broken down to release carbon dioxide for use in photosynthesis.

A) It is used for carbon fixation. In the CAM (Crassulacean Acid Metabolism) pathway, PEP is used for the initial step of carbon fixation in the plant. PEP carboxylase enzyme fixes CO2 into PEP, forming oxaloacetate, which is then converted to malate and stored in the vacuole. During the day, the malate is transported to the chloroplast, where it is decarboxylated to release CO2 for use in the Calvin cycle.

Answer: B) During the night. Organic acids are synthesized during the night in CAM plants and stored until they can be used for photosynthesis during the day.

Answer: D) All of the above. Light intensity, temperature, and water availability are all factors that can influence the CAM pathway in plants.

Answer: D) Malic enzyme. Malic enzyme is responsible for the conversion of malate to pyruvate during the day in CAM plants.

Answer: D) Rice. Rice is a C3 plant, while pineapple, cactus, and agave are examples of CAM plants.

Answer: C) In the vacuoles. During the day, CAM plants store carbon dioxide in their vacuoles until it can be used for photosynthesis.

Answer: A) Higher water-use efficiency. CAM plants have a higher water-use efficiency compared to C3 and C4 plants because they open their stomata at night when the air is cooler and more humid.

Answer: C) They live in dry environments. CAM plants have evolved to live in arid environments and use CAM photosynthesis to conserve water.

Answer: C) They live in dry environments. CAM plants have evolved to live in arid environments and use CAM photosynthesis to conserve water.

Answer: d) It allows them to maintain a high rate of photosynthesis even under water stress. CAM plants can reduce water loss by opening their stomata at night when it is cooler and more humid, and then store the CO2 they take up in the form of organic acids. During the day, the stomata close to reduce water loss, but the CO2 stored in the form of organic acids can be released for use in photosynthesis.

Answer: a) CAM plants keep their stomata open during the night and close them during the day. This is the opposite of C3 and C4 plants, which keep their stomata open during the day and close them at night.

Answer: c) To increase water use efficiency. In arid environments, water is a limiting resource for plants. CAM plants can reduce water loss by opening their stomata at night when it is more relaxed and more humid, and then storing the CO2 they take up in the form of organic acids. During the day, the stomata are close to reducing water loss, and the CO2 is released from the organic acids for photosynthesis.

A) They can fix CO2 more efficiently under high temperature and low CO2 conditions. CAM plants use PEP carboxylase to fix CO2 during the night, allowing them to reduce water loss during the day. This also allows them to fix CO2 more efficiently under conditions of low CO2 and high temperature, which is especially important in arid environments.

Answer: A) To maximize water usage. The CAM pathway allows plants to fix CO2 at night when the stomata are open, reducing water loss during the day when the stomata are closed. This is particularly important in arid environments where water is limited. The pathway also allows for more efficient carbon fixation under conditions of low CO2 and high temperature.

Answer: d) To transport CO2 from the mesophyll cells to the bundle sheath cells. In CAM plants, CO2 initially enters the mesophyll cells and is fixed into malic acid. At night, the malic acid is transported to the bundle sheath cells, where it is decarboxylated to release CO2 for use in the Calvin cycle.