Q: Which of the following best describes the overall chemical equation for photosynthesis in plants?

$$6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{Light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2$$

Question 1

Which of the following best describes the overall chemical equation for photosynthesis in plants?

Accepted Answer

$$6 	ext{CO}_2 + 6 	ext{H}_2	ext{O} + 	ext{Light energy} ightarrow 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6 	ext{O}_2$$

Question 2

What is the primary function of the light-dependent reactions of photosynthesis?

Accepted Answer

To produce ATP and NADPH for use in the Calvin cycle

Question 3

Which pigment is the main photosynthetic pigment in most plants, and what is its primary role?

Accepted Answer

Chlorophyll a; it initiates the light-dependent reactions by losing electrons when excited by light

Question 4

Why do plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects light in the 500-600 nm range, which corresponds to green wavelengths

Question 5

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

It is an anabolic, endergonic pathway that uses ATP and NADPH to reduce CO$$_2 to $$carbohydrates

Question 6

What is the role of water in the light-dependent reactions of photosynthesis?

Accepted Answer

It is split to provide electrons and protons, releasing O$$_2 as a by-$$product

Question 7

Which enzyme is responsible for fixing CO$$_2 in $$the Calvin cycle, and why is it significant?

Accepted Answer

RuBisCo; it is the most abundant protein on Earth and catalyzes the first step of carbon fixation

Question 8

In C4 plants, what adaptation allows them to minimize photorespiration under hot, dry conditions?

Accepted Answer

They use PEP carboxylase to initially fix CO$$_2 in $$mesophyll cells, forming a 4-carbon compound that is transported to bundle sheath cells

Question 9

Which process is responsible for the production of ATP in the light-dependent reactions, and what drives it?

Accepted Answer

Photophosphorylation; driven by the flow of H$$^+$$ ions through ATP synthase due to a proton gradient across the thylakoid membrane

Question 10

A plant is exposed to only green light. What is the most likely outcome for its rate of photosynthesis, and why?

Accepted Answer

The rate will decrease because chlorophyll reflects green light and cannot use it efficiently for photosynthesis

Question 11

Which of the following best explains why cyclic electron flow occurs in the light reactions of photosynthesis?

Accepted Answer

To generate additional ATP without producing NADPH or O$$_2$$, balancing the ATP/NADPH ratio for the Calvin cycle

Question 12

What is the main difference between the light-dependent reactions in C3 and C4 plants?

Accepted Answer

There is no major difference; both use the same light-dependent reactions, but C4 plants have an additional CO$$_2$$ fixation step before the Calvin cycle

Question 13

Which of the following statements about photorespiration is correct?

Accepted Answer

It occurs when RuBisCo binds O$$_2$$ instead of CO$$_2$$, resulting in the consumption of ATP without producing sugars

Question 14

Which of the following best describes the fate of the oxygen atoms from water molecules during photosynthesis?

Accepted Answer

They are released as molecular oxygen (O$$_2) $$during the light-dependent reactions

Question 15

A scientist uses a spectrophotometer to analyze chlorophyll. Which wavelengths would show the highest absorption?

Accepted Answer

Around 430 nm (blue) and 660 nm (red)

Question 16

Which of the following is a correct description of resonance energy transfer in photosystems?

Accepted Answer

Energy from an excited electron in one chlorophyll molecule excites an electron in a neighboring chlorophyll, without the electron itself moving

Question 17

Which of the following best explains why the Calvin cycle is considered endergonic?

Accepted Answer

It requires an input of energy in the form of ATP and NADPH to convert CO$$_2$$ into carbohydrates

Question 18

What is the main advantage of the C4 pathway over the C3 pathway in hot, dry environments?

Accepted Answer

C4 plants minimize photorespiration by concentrating CO$$_2 in $$bundle sheath cells, increasing the efficiency of the Calvin cycle

Question 19

Which of the following is NOT a product of the light-dependent reactions of photosynthesis?

Accepted Answer

Glucose

bio123 CH10 UNIT 2 -Photosynthesis: Mechanisms, Structure, and Adaptations

Study Guide - Practice Questions

Study Guide - Flashcards