Nitrogen fixation is basically a process of converting nitrogen gas into ammonia (NH₃). One of the key enzymes in the process is "nitrogenase". The production and activity of nitrogenase is very highly regulated as highlighted below:

A. Nitrogen fixation through nitrogenase is an energetically expensive process.

B. Nitrogenase encoding gene is under a constitutive promoter.

C. Nitrogenase is highly sensitive to oxygen.

D. Endogenousavailability of the cofactor of nitrogenase enzyme is very low.

Which one of the following combinations of above statements is correct?

• A and B

• A and C

• B and C

• B and D

Following statements are related to oxidative phosphorylation.

A. Redox reactions of electron transport chain coupled with ATP synthesis are collectively called oxidative phosphorylation.

B. Three major processes: glycolysis, oxidative pentose phosphate pathway and critic acid cycle are related to oxidative phosphorylation.

C. Electron transport proteins are bound to outer of the two mitochondrial membranes.

D. In the electron transport chain electrons are transferred to oxygen from NADH.

Which one of the following combinations of above statements is correct?

• A and D

• B and C

• C and D

• A and C

Which of the following statements is NOT correct?

• Stomata are present in mosses and hornworts but absent in liverworts.

• Only the lycophytes have microphylls and almost all other vascular plants have megaphylls.

• Monocot pollen grains have three opening whereas eudicot pollen grains have one opening.

• Monocots have fibrous root system whereas eudicots have taproot.

Which of the following characteristics make Amborella the most basal living angiosperm?

• Carpels fused by tissue and absence of vessel elements.

• Absence of carpels and presence of vessel elements.

• Carpels free and presence of vessel elements.

• Presence of carpels and absence of vessel elements.

Following are some statements related to osmotic stress in plants.

A. The accumulation of ions during osmotic adjustment is predominantly restricted to the vacuoles.

B. In order to maintain the water potential equilibrium within the cell, other solutes called as compatible solutes or compatible osmolytes accumulate in the cytoplasm.

C. Galactose is one of the compatible osmolytes involved in osmotic stress in plants.

D. There are mainly four groups of molecules that frequently serve as compatible solutes.

Which one of the following combinations of above statements is correct?

• A, B and C

• B, C and D

• A, B and D

• A, C and D

86.

Following are certain statements regarding C₃, C₄ and CAM plants?

A. The ratio of water loss to CO₂ uptake is higher in CAM plants than it is in either C₃ and C₄ plants.

B. The rate of photosynthesis attains maximum rate at lower intracellular CO₂ partial pressure in C₄ plants than in C₃ plants.

C. The compensation point in C₃ plants are always lower than C₄ plants.

D. Plants with C₄ metabolism need less rubisco than C₃ plants to achieve a given rate of photosynthesis.

Which one of the following combinations of the above statements is correct?

• A and B

• A and C

• C and D

• B and D

Following are certain statements regarding secondary metabolites found in plants:

A. All terpenes are derived from a six-carbon element.

B. Alkaloids are nitrogen-containing compounds.

C. Pyrethroids, a monoterpene ester found in the leaves and flower of Chrysanthemum species, show insecticidal activity.

D. Limonoids are groups of alkaloids and have antiherbivoral activity.

Which one of the following combinations of above statements is correct?

• A and B

• A and D

• B and C

• C and D

The plant hormone indole-3-acetic acid (IAA) is present in most plants. The structure of this hormone is related to which one of the following amino acids?

• Glutamic acid

• Aspartic acid

• Lysine

• Tryptophan

Which one of the following is NOT a characteristic property of carotenoids?

• They possess complex porphyrin ring.

• They are integral constituent of thylakoid membrane.

• They are also called accessory pigments.

• They protect plants from damages caused by light.

Which one of the following is NOT the main factor that contributes to water potential during plant growth under normal conditions?

• Solute potential

• Hydrostatic pressure

• Gravity

• Temperature