FREE NEET Biology Practice MCQ Test: Photosynthesis In Higher Plants Exercise 2 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

Answer: (d)

Answer: (b)

Type I photosystems use ferredoxin like iron-sulphur cluster proteins as terminal electron acceptors, while type II photosystems ultimately shuttle electrons to a quinone terminal electron acceptor. One has to note that both reaction centres types are present in chloroplasts of plants and cyanobacteria, working together to form an unique photosynthetic chain able to extract electrons from water, evolving oxygen as a byproduct.

Answer: (a)

Crassulacean acid metabolism (CAM) is photosynthesis by the $C_4$ pathway in which carbon dioxide is taken up during the night, when the plant's stomata are open and fixed into malic acid. During the day, when the stomata are closed, carbon dioxide is released from malic acid for use in the Calvin cycle. This is important for plants that live in arid conditions as it enables them to keep their stomata closed during the day to reduce water loss from evaporation. Crassulacean acid metabolism is common in succulent plants of desert regions, including cacti and in certain ferns.

Answer: (c)

The discovery of Emerson effect stated that one group of pigments absorbs light of both shorter and longer wavelengths (more than 680 nm) and another group of pigment absorbs light on only shorter wavelengths (less than 680 nm). These two groups of pigments are known as pigment systems or photosystems.

Answer: (a)

Answer: (d)

In $C_{4}$ plants , the process by which $C_{4}$ acids are converted into $C_{3}$ acids in the bundle sheath cell is known as decarboxylation. Shortly after the discovery of the $C_{4}$ cycle the Crassulacean acid metabolism (CAM) pathway was dissected and elucidated as a $C_{4}$ variant. This pathway is found in desert succulents and epiphytes. In the typical $C_{4}$ cycle, the fixation reaction occurred in a mesophyll cell and the decarboxylation reaction occurred in a bundle sheath cell, Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide ($CO_{2}$ ). Enzymes that catalyze decarboxylation are called decarboxylases.

Answer: (a)

Answer: (a)

Answer: (b)

In $C_{4}$ plants, bundle sheath cells are rich in RuBisCO, but lack PEPcase. The $CO_{2}$ released in the bundle sheath cells enters the $C_{3}$ or the Calvin pathway, common to all plants. Thus, the basic pathway that results in the formation of sugars, the Calvin pathway is common to the $C_{3}$ and $C_{4}$ plants.

Answer: (c)

$C_4$ plants respond to higher temperature with enhanced photosynthesis while $C_3$ plants have lower temperature optimum.

Answer: (d)

Answer: (a)

The use of radioactive $^{14}C$ by Melvin Calvin in algal photosynthesis studies had led to the discovery that the first $CO_{2}$ fixation product was a 3-carbon organic acid.

Answer: (b)

Answer: (a)

In $C_{3}$ plants photosynthesis decreases at higher temperatures due to increased photorespiration. $C_{4}$ plants have higher temperature optimum because of the presence of enzyme called pyruvate phosphatedikinase, which is sensitive to low temperature.

Answer: (c)

Answer: (a)

Answer: (d)

In non-cyclic reaction of photosynthesis, electrons from chlorophyll molecules in photosystem I are used in the formation of NADPH. The source of those electrons is photosystem II which splits water molecule.

Answer: (a)

Photosynthetic pigments are found in the thylakoid membrane of chloroplasts. The grana lamellae are paired to form sac like structures and form thylakoids. Chlorophylls and other photosynthetic pigments are confined to grana.

Answer: (d)