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

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

Question 1

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

Accepted Answer

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

Question 2

During the light reactions of photosynthesis, what is the primary function of water?

Accepted Answer

To provide electrons to replace those lost by chlorophyll in photosystem II

Question 3

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

Accepted Answer

Chlorophyll a; it absorbs light energy to drive the light reactions

Question 4

Why do leaves appear green to the human eye?

Accepted Answer

Because chlorophyll reflects and transmits green wavelengths of light

Question 5

Which of the following best explains why shorter wavelengths of light have more energy than longer wavelengths?

Accepted Answer

Energy of a photon is inversely proportional to its wavelength: $$E = \frac{hc}{\lambda}$$

Question 6

What is the main purpose of the Calvin cycle in photosynthesis?

Accepted Answer

To use ATP and NADPH to convert $$\mathrm{CO}_2$$ into glyceraldehyde-3-phosphate (G3P)

Question 7

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

Accepted Answer

Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase)

Question 8

In which part of the chloroplast do the light-dependent reactions take place?

Accepted Answer

Thylakoid membrane

Question 9

Which of the following is a direct product of the noncyclic (linear) electron flow during the light reactions?

Accepted Answer

ATP, NADPH, and $$\mathrm{O}_2$$

Question 10

Why is cyclic electron flow important in photosynthesis?

Accepted Answer

It generates additional ATP needed for the Calvin cycle without producing NADPH

Question 11

What is the main adaptive advantage of C4 plants over C3 plants in hot, dry climates?

Accepted Answer

C4 plants minimize photorespiration and conserve water by spatially separating carbon fixation and the Calvin cycle

Question 12

Which of the following statements about photorespiration is correct?

Accepted Answer

Photorespiration occurs when rubisco adds $$\mathrm{O}_2$$ instead of $$\mathrm{CO}_2 to $$RuBP, leading to the release of $$\mathrm{CO}_2$$

Question 13

Which of the following best describes the role of ATP synthase in the chloroplast?

Accepted Answer

It synthesizes ATP as protons flow from the thylakoid lumen to the stroma

Question 14

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

Accepted Answer

Glucose

Question 15

What is the main function of carotenoids in the photosynthetic apparatus?

Accepted Answer

They absorb excess light energy that could damage chlorophyll and broaden the spectrum of light used for photosynthesis

Question 16

Which of the following best explains why CAM plants are well adapted to arid environments?

Accepted Answer

They open their stomata at night to minimize water loss and store CO2 as malate

Question 17

Which of the following statements about the relationship between photosynthesis and cellular respiration is correct?

Accepted Answer

The products of photosynthesis are the reactants for cellular respiration

Question 18

How many ATP and NADPH molecules are required to produce one molecule of glucose via the Calvin cycle?

Accepted Answer

18 ATP and 12 NADPH

Question 19

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

Accepted Answer

They are released as molecular oxygen ($$\mathrm{O}_2) $$during the light reactions

Photosynthesis: Mechanisms, Structures, and Adaptations

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