Question

Herbicides kill plants by inhibiting

• A. PS I
• B. PS II
• C. Translocation
• D. Both A and B

Answer 1

The correct option is D Both A and B

Herbicides are substances that kill unwanted plants. It works by inhibiting photosynthesis. There are two sites of action for herbicides. These are photosystem II (PS II) and photosystem I (PS I). In PS II, it binds to the DI protein and blocking electron transfer to plastoquinone. This results in inhibition of conversion of absorbed light energy into electrochemical energy. PS I electron acceptors probably accept electrons from the iron-sulfur. The free radical from the herbicide results in the production of hydroxyl radicals. Hence, it blocks electron transport and stops CO22 fixation and production of energy required for plant growth.

Thus, the correct answer is option D.