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

Question 1

Which of the following statements best describes the role of autotrophs in the biosphere?

Accepted Answer

Autotrophs sustain themselves without eating anything derived from other organisms.

Question 2

In the process of photosynthesis, which equation correctly represents the overall chemical reaction?

Accepted Answer

$$6CO_2 + 6H_2O + 	ext{Light energy} ightarrow C_6H_{12}O_6$ + 6O_2$$

Question 3

Which structure within the chloroplast is primarily responsible for the light reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 4

What is the main function of stomata in plant leaves?

Accepted Answer

To allow the exchange of CO$$_2$$ and O$$_2$$ gases

Question 5

During the light reactions of photosynthesis, which molecule is reduced?

Accepted Answer

NADP$$^+$$

Question 6

Which pigment is primarily responsible for the green color of plants and is essential for photosynthesis?

Accepted Answer

Chlorophyll a

Question 7

What is the role of water ($$H_2O) in $$the light reactions of photosynthesis?

Accepted Answer

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

Question 8

Which enzyme catalyzes the first step of carbon fixation in the Calvin cycle?

Accepted Answer

Rubisco

Question 9

In the Calvin cycle, for the net synthesis of one molecule of glyceraldehyde 3-phosphate (G3P), how many molecules of CO$$_2$$ must be fixed?

Accepted Answer

Three

Question 10

Which of the following best explains why photosynthesis is considered an endergonic process?

Accepted Answer

It requires an input of energy from sunlight to drive the reaction.

Question 11

Which of the following statements about the spatial organization of chemiosmosis in chloroplasts and mitochondria is correct?

Accepted Answer

Chloroplasts use the thylakoid space and stroma, while mitochondria use the intermembrane space and matrix.

Question 12

Which process in photosynthesis directly generates ATP from ADP and inorganic phosphate ($$P_i$$)?

Accepted Answer

Photophosphorylation

Question 13

What is the primary function of the Calvin cycle in photosynthesis?

Accepted Answer

To form sugar from CO$$_2$$ using ATP and NADPH

Question 14

Which of the following is a correct description of the fate of electrons in the linear electron flow of photosynthesis?

Accepted Answer

Electrons move from water to NADP$$^+$$, forming NADPH.

Question 15

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

Accepted Answer

Glucose

Question 16

Why do plants appear green to our eyes?

Accepted Answer

Chlorophyll reflects green light and absorbs red and blue light.

Question 17

Which of the following statements about the enzyme PEP carboxylase in C$$_4$$ plants is correct?

Accepted Answer

PEP carboxylase can fix CO$$_2$$ even when CO$$_2$$ concentrations are low.

Question 18

Which of the following best describes the function of accessory pigments such as carotenoids in photosynthesis?

Accepted Answer

They absorb excessive light that could damage chlorophyll.

Question 19

In a scenario where atmospheric CO$$_2$$ levels increase, which type of plant is likely to be affected differently, and why?

Accepted Answer

C$$_3$$ and C$$_4$$ plants, because their carbon fixation pathways respond differently to CO$$_2$$ concentration.

Question 20

Which of the following is a real-world application of understanding the Calvin cycle in agriculture?

Accepted Answer

Improving crop yield by enhancing the efficiency of carbon fixation enzymes.

Photosynthesis: Mechanisms and Sites in Plants

Study Guide - Practice Questions