Question 1

Which of the following best summarizes the overall equation for the light-dependent reactions of photosynthesis in oxygenic phototrophs?

Accepted Answer

$$2\ \mathrm{H}_2O + 2\ \mathrm{NADP}^+ + 3\ \mathrm{ADP} + 3\ \mathrm{P_i} + 2\ \mathrm{H}^+ \rightarrow 2\ \mathrm{NADPH} + 2\ \mathrm{H}^+ + 3\ \mathrm{ATP} + \mathrm{O}_2$$

Question 2

In eukaryotic cells, where do the light-dependent reactions of photosynthesis occur?

Accepted Answer

In the thylakoid membranes of chloroplasts

Question 3

A plant is found to lack iron. What is the most likely effect on its light-dependent reactions?

Accepted Answer

Electron transport would be disrupted, reducing ATP and NADPH production

Question 4

Which molecule acts as the primary electron donor in oxygenic photosynthesis, and what is the fate of its electrons in the non-cyclic pathway?

Accepted Answer

Water; electrons flow from water to NADP$$^+$$, forming NADPH

Question 5

Which protein complex is responsible for capturing light energy and initiating electron flow in the light-dependent reactions?

Accepted Answer

Photosystem II

Question 6

Compare oxidative phosphorylation and photophosphorylation. Which statement is correct?

Accepted Answer

Oxidative phosphorylation uses oxygen as the terminal electron acceptor, while photophosphorylation uses NADP$$^+$$

Question 7

What is the summary equation for the Calvin-Benson cycle?

Accepted Answer

$$6\ \mathrm{CO}_2 + 12\ \mathrm{NADPH} + 18\ \mathrm{ATP} \rightarrow C_6H_{12}O_6$ + 12\ \mathrm{NADP}^+ + 18\ \mathrm{ADP} + 18\ \mathrm{P_i}$$

Question 8

Which enzyme catalyzes the first reaction of the Calvin-Benson cycle, and what are its substrates?

Accepted Answer

RuBisCO; substrates are CO$$_2$$ and ribulose-1,5-bisphosphate

Question 9

How many turns of the Calvin-Benson cycle are required to produce one molecule of glucose?

Accepted Answer

6

Question 10

If a plant is placed in the dark, would it still be able to generate ATP? Why?

Accepted Answer

No, because ATP synthesis in chloroplasts requires light to drive electron transport

Question 11

What would happen to RuBisCO activity and the Calvin-Benson cycle when CO$$_2$$ levels are low in an oxygenic phototroph?

Accepted Answer

RuBisCO activity decreases, and the Calvin-Benson cycle slows down

Question 12

Which of the following is a strategy evolved by plants to survive in hot, dry climates, and what problem does it solve?

Accepted Answer

C$$_4$$ photosynthesis; reduces photorespiration by concentrating CO$$_2$$

Question 13

A cactus and a typical flower are placed on a sunny windowsill. What should a plant parent do to ensure both survive?

Accepted Answer

Provide minimal water to the cactus and regular water to the flower, considering their adaptations

Question 14

If a plant lacked magnesium, what would be the most direct effect on photosynthesis?

Accepted Answer

Chlorophyll would not function properly, reducing light absorption

Question 15

How is the proton gradient generated during photosynthesis?

Accepted Answer

By pumping protons from the stroma into the thylakoid lumen during electron transport

Question 16

How many electrons from water are needed to create one molecule of G-3-P (glyceraldehyde-3-phosphate) in photosynthesis?

Accepted Answer

12

Question 17

Suppose a photosynthetic cell creates an excess of NADH. What would happen to the process of photosynthesis?

Accepted Answer

Photosynthesis would be disrupted because NADPH is required, not NADH

Question 18

Why is there little free glucose in photosynthetic cells despite the summary equation showing glucose as a product?

Accepted Answer

Glucose is immediately converted to starch or sucrose for storage or transport

Question 19

Where in a photosynthetic cell is starch synthesized?

Accepted Answer

In the stroma of the chloroplast

Step-by-Step Guidance for Photosynthesis Study Questions (Cell Biology)

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