Question

1. where does the light reaction take place?
2. circle the letter of the carrier molecule involved in photosynthesis.

a. h20 c. c02
b. nadp+ d. 02
phase two: calvin cycle (pg 226)

1. what does the calvin cycle use to produce high - energy sugars?

1. why are the reactions of the calvin cycle also called the light - independent reactions?
2. where is the energy needed for the calvin cycle to build bonds coming from?

Explanation:

1. The light reaction of photosynthesis occurs in the thylakoid membranes of chloroplasts. Chloroplasts are the organelles in plant cells where photosynthesis takes place. Thylakoids are disk - shaped structures within chloroplasts, and their membranes contain the pigments (like chlorophyll) and proteins necessary for capturing light energy and converting it into chemical energy (ATP and NADPH).
2. NADP+ (Nicotinamide adenine dinucleotide phosphate) is a carrier molecule in photosynthesis. In the light reactions, NADP+ accepts electrons and hydrogen ions to form NADPH. NADPH then carries high - energy electrons to the Calvin cycle. H₂O is a reactant in the light reactions (split to release oxygen), CO₂ is a reactant in the Calvin cycle, and O₂ is a product of the light reactions.
3. The Calvin cycle uses carbon dioxide (CO₂), ATP (adenosine triphosphate), and NADPH (nicotinamide adenine dinucleotide phosphate - hydrogen) to produce high - energy sugars. ATP provides the energy, NADPH provides the reducing power (high - energy electrons), and CO₂ is the carbon source.
4. The reactions of the Calvin cycle are called light - independent reactions because they do not directly require light. While the light reactions (which are light - dependent) produce ATP and NADPH that are used in the Calvin cycle, the Calvin cycle itself can occur in the absence of light as long as ATP and NADPH are available.
5. The energy needed for the Calvin cycle to build bonds comes from ATP (produced in the light reactions) and NADPH (also produced in the light reactions). ATP provides energy in the form of phosphate groups (when it hydrolyzes to ADP + Pi), and NADPH donates high - energy electrons that are used in the synthesis of organic molecules (sugars) from CO₂.

Answer:

1. Thylakoid membranes of chloroplasts
2. b. NADP+
3. Carbon dioxide (CO₂), ATP, and NADPH
4. Because they do not directly require light (they use ATP and NADPH from the light reactions)
5. ATP and NADPH (produced in the light reactions)