Question

Herbicides are chemicals used to kill or inhibit the growth of unwanted plants and weeds. Many herbicides work by blocking electron carriers, or reducing their ability to carry electrons, in the light dependent reactions. One such chemical is DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea). DCMU is an algaecide and herbicide that works by blocking the electron binding site of plastoquinone. This means that photosystem II is unable to transfer electrons from the splitting of water to plastoquinone. This effectively shuts down the linear flow of electrons in the light dependent reactions. a) Identify the molecule produced in the light dependent reactions that would be most affected by the shutting down of linear electron flow. b) Justify your reasoning with an explanation. c) Connect how the molecule affected in part (a) is used in the Calvin cycle. d) Describe what would effectively happen to the Calvin cycle as a result of exposure to DCMU

Answer 1

Answer:

Oxygen.

Explanation:

Oxygen molecule that is produced in the light dependent reactions. This shutting down of linear electron flow greatly affected the production of oxygen. Photosystem II gains replacement electrons from splitting of water molecules into hydrogen ions (H+) and oxygen atoms so if the electron flow is disturbed then oxygen production is greatly affected.