Question

The herbicide DCMU kills the weeds because it inhibits __________.

• A. respiration
• B. $C{O}_2$ fixation
• C. cell division
• D. $N{O}_3^{2-}$ uptake

Answer 1

The correct option is B $C{O}_2$ fixation

DCMU (Dichlorophenyl dimethyl urea) is a herbicide which kills the weeds by inhibiting $C{O}_2$ fixation as it is a strong inhibitor of photosystem II ($P_{680}$).DCMU acts by blocking electron flow at the guanine acceptors of PS II, by competing for the binding site of plastoquinone.

So the correct option is B.