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

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

Question 1

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

Accepted Answer

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

Question 2

Which molecule is oxidized and which is reduced during photosynthesis?

Accepted Answer

H$$_2O is $$oxidized and CO$$_2 is $$reduced

Question 3

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

Accepted Answer

It absorbs violet-blue and red light, driving the light reactions

Question 4

Why do leaves appear green to our eyes?

Accepted Answer

Chlorophyll reflects green light and absorbs other wavelengths

Question 5

Which of the following is a direct product of the Calvin cycle?

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 6

What is the main function of the light reactions in photosynthesis?

Accepted Answer

To generate ATP and NADPH for the Calvin cycle

Question 7

Which structure in the chloroplast is the site of the light-dependent reactions?

Accepted Answer

Thylakoid membrane

Question 8

What is the role of accessory pigments such as carotenoids in photosynthesis?

Accepted Answer

They absorb excessive light that would damage chlorophyll

Question 9

Which of the following best explains why almost all heterotrophs depend on photoautotrophs?

Accepted Answer

Photoautotrophs provide food and oxygen

Question 10

A scientist uses a spectrophotometer to measure the absorption of different wavelengths by chlorophyll. Which result would indicate the highest absorption?

Accepted Answer

A low transmittance (high absorption) reading

Question 11

Which phase of the Calvin cycle involves the enzyme rubisco?

Accepted Answer

Carbon fixation

Question 12

If a plant is exposed only to green light, what would you expect to happen to its rate of photosynthesis?

Accepted Answer

It would decrease because green light is mostly reflected

Question 13

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

Accepted Answer

CO$$_2$$

Question 14

In Jan Baptist van Helmont’s experiment, what did he conclude was responsible for the increase in mass of the willow tree?

Accepted Answer

The water

Question 15

Which of the following best describes the relationship between photosynthesis and cellular respiration in the biosphere?

Accepted Answer

Photosynthesis stores energy in organic molecules, cellular respiration releases it as ATP

Question 16

Which of the following is the correct sequence of events in the light reactions?

Accepted Answer

Absorption of light by chlorophyll, splitting of water, electron transport, formation of NADPH and ATP

Question 17

Why is the Calvin cycle sometimes referred to as the 'dark reactions'?

Accepted Answer

It does not directly require light to proceed

Question 18

Which of the following best explains why plants store excess sugar as starch?

Accepted Answer

Starch is insoluble and can be stored without affecting osmotic balance

Question 19

A mutation disables the enzyme NADP$$^+$$ reductase in a plant cell. Which process would be directly affected?

Accepted Answer

The reduction of NADP$$^+ to $$NADPH during the light reactions

Question 20

Which of the following best describes the fate of oxygen produced during photosynthesis?

Accepted Answer

It is released as a byproduct into the atmosphere

Photosynthesis: The Process That Feeds the Biosphere

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