Question

which statements describe the light - dependent reactions of photosynthesis, which describe the calvin cycle (light - independent reactions of photosynthesis), and which describe both?
light - dependent reactions
calvin cycle
both the light - dependent reactions and the calvin cycle
answer bank
happen inside chloroplasts in plants
need ribulose bisphosphate
synthesize atp and nadph
produce sugars
generate oxygen gas
require water
use chlorophyll to capture light energy
use co₂

Explanation:

• Light - dependent reactions:
• They use chlorophyll to capture light energy. Chlorophyll is located in the thylakoid membranes of chloroplasts. When light hits chlorophyll, it excites electrons.
• They require water. Water is split during the light - dependent reactions. The equation for the splitting of water is \(2H_2O

ightarrow4H^{+}+O_2 + 4e^{-}\).

• They synthesize ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). This occurs through the electron transport chain and chemiosmosis.
• Calvin cycle:
• It needs ribulose bisphosphate (\(RuBP\)). \(RuBP\) reacts with \(CO_2\) in the first step of the Calvin cycle, catalyzed by the enzyme rubisco.
• It uses \(CO_2\). \(CO_2\) is fixed (incorporated into an organic molecule) during the Calvin cycle.
• It produces sugars. The end - product of the Calvin cycle is glyceraldehyde - 3 - phosphate (\(G3P\)), which can be used to synthesize glucose and other sugars.
• Both:
• They happen inside chloroplasts in plants. The light - dependent reactions occur in the thylakoid membranes and the Calvin cycle occurs in the stroma of the chloroplast.

Answer:

• Light - dependent reactions: synthesize ATP and NADPH, generate oxygen gas, require water, use chlorophyll to capture light energy
• Calvin cycle: need ribulose bisphosphate, use \(CO_2\), produce sugars
• Both: happen inside chloroplasts in plants