Question

PLZZ HELP!!!!!

Atrazine is an herbicide that prevents plant growth by inhibiting photosynthesis. Atrazine works by binding to proteins in the electron transport chain of photosystem II. Once atrazine binds to the proteins, electrons can no longer travel down the chain to reach photosystem I.

Based on this information, how does atrazine stop plant growth?

A. It prevents the formation of NADH and FADH2, which are needed by the light-independent reactions to fix carbon.

B. It prevents chlorophyll from creating electrons, which are needed by the light-dependent reactions to make sugars.

C. It prevents the formation of ATP and NADPH, which are needed by the light-independent reactions to make sugars.

D. It prevents water from releasing oxygen, which is needed by the light-dependent reactions to fix carbon.

Answer 1

C. It prevents the formation of ATP and NADPH, which are needed by the light-independent reactions to make sugars.

Answer 2

The correct answer is option C, that is, it prevents the formation of ATP and NADPH, which are needed by the light-independent reactions to make sugars.

The herbicide atrazine combines with the D1 protein and inhibits the binding of plastoquinone. By obstructing the binding of plastoquinone, the procedure of photosynthetic transfer of electron is disturbed, and thus, the production of ATP and NADPH in the chloroplast gets compromised.

This leads to an incapacity to fix carbon dioxide and generate the nutrients required for the plant to live. The block in the transfer of electrons also results in an oxidative stress and the production of radicals that lead to brisk cellular destruction.