Question

During photosynthesis, plants

• A. absorb $O_2$, release $CO_2$
• B. release $O_2$, absorb $CO_2$
• C. absorb $N_2$, release $O_2$
• D. absorb $N_2$, release $NH_3$

Answer 1

Answer: (B)

release $O_2$, absorb $CO_2$

Answer 2

Photosynthesis is the chemical process by which green plants and other phototrophs synthesize organic compounds from carbon dioxide and water in the presence of sunlight. It occurs in the chloroplasts. The light-dependent reactions require the presence of light, energy from sunlight is absorbed by photosynthetic pigments (chiefly the green pigment chlorophyll) and used to bring about the photolysis of water : $H_2O \to 2H^+ + 2e^- + 1/2 O_2$ The electrons released by this reaction pass along a series of electron carrier molecules; as they do so they lose their energy, which is used to convert $ADP$ to $ATP$ in the process of photophosphorylation. The electrons and protons produced by the photolysis of water are used to reduce $NADP$. $2H^+ + 2e ^-+ NADP^+ \to NADPH + H^+$ The $ATP$ and $NADPH$ produced during the light-dependent reactions provide energy and reducing power, respectively, for the ensuing light-independent reactions. During these reactions carbon dioxide is reduced to carbohydrate in metabolic pathway known as the Calvin cycle. Photosynthesis can be summarized by the equation; $CO_2 + 2H_2O \to [CH_2O_2] + H_2O + O_2$