Question 1

Which of the following best explains the primary source of increased biomass in photosynthetic organisms, as demonstrated by early plant growth experiments?

Accepted Answer

Carbon dioxide from the atmosphere

Question 2

Which equation correctly represents the overall process of photosynthesis in plants?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 3

In the light-dependent reactions of photosynthesis, what is the primary role of chlorophyll?

Accepted Answer

To capture energy from sunlight and transfer it to ATP and NADPH production

Question 4

Which statement best describes the relationship between photon wavelength and energy in photosynthesis?

Accepted Answer

Shorter wavelength photons have higher energy

Question 5

What is the function of the enzyme Rubisco in the Calvin Cycle?

Accepted Answer

It catalyzes the fixation of CO$$_2 to $$ribulose-1,5-bisphosphate (RuBP)

Question 6

During the Calvin Cycle, how many ATP and NADPH molecules are consumed for each CO$$_2$$ fixed?

Accepted Answer

3 ATP and 1 NADPH

Question 7

Which of the following is a correct sequence of events in the light-dependent reactions of photosynthesis?

Accepted Answer

Light excites electrons in Photosystem II, electrons move through electron transport chain, ATP and NADPH are produced

Question 8

What is the main purpose of the proton gradient established across the thylakoid membrane during photosynthesis?

Accepted Answer

To power ATP synthase for ATP production

Question 9

Which pigment acts as an accessory pigment in photosynthesis, absorbing photons of different energy than chlorophyll a?

Accepted Answer

Chlorophyll b

Question 10

Why do leaves appear green to the human eye?

Accepted Answer

Chlorophyll reflects green light

Question 11

Which process occurs in the stroma of the chloroplast?

Accepted Answer

Calvin Cycle (light-independent reactions)

Question 12

What is the first stable product formed when Rubisco fixes CO$$_2 in $$the Calvin Cycle?

Accepted Answer

3-phosphoglycerate (3-PGA)

Question 13

Photorespiration occurs when Rubisco uses O$$_2$$ instead of CO$$_2. $$What is the consequence of this process for the plant?

Accepted Answer

Decreased efficiency of photosynthesis

Question 14

Which adaptation allows C$$_4$$ plants to minimize photorespiration?

Accepted Answer

Using PEP carboxylase to fix CO$$_2$$ before delivering it to Rubisco

Question 15

In CAM plants, how is CO$$_2$$ managed to reduce water loss during hot days?

Accepted Answer

CO$$_2 is $$fixed to malate at night and used during the day

Question 16

Which of the following best describes the Emerson Enhancement Effect?

Accepted Answer

Photosynthetic rate increases when both 680 nm and 700 nm light are provided together

Question 17

A plant is exposed to only green light. What is the expected effect on its photosynthetic rate?

Accepted Answer

Photosynthetic rate will decrease

Question 18

Which molecule acts as the final electron acceptor in the light-dependent reactions of photosynthesis?

Accepted Answer

NADP$$^+$$

Question 19

If a mutation caused Rubisco to lose its affinity for CO$$_2$$ but retain affinity for O$$_2$$, what would be the most likely outcome for the plant?

Accepted Answer

Increased photorespiration and decreased photosynthetic efficiency

Question 20

Which of the following best describes the role of stomata in photosynthesis?

Accepted Answer

They allow for gas exchange, enabling CO$$_2$$ uptake and O$$_2$$ release

Photosynthesis and the Calvin Cycle: Biochemical Principles and Mechanisms

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