Question 1

Which of the following best describes the relationship between photosynthesis and cellular respiration in the ecosystem, as illustrated in the first image?

Accepted Answer

Photosynthesis produces oxygen and organic molecules, which are used in cellular respiration to generate ATP, while cellular respiration releases CO$$_2$$ and H$$_2O $$used in photosynthesis.

Question 2

According to the second image, what is the primary fate of light energy entering an ecosystem?

Accepted Answer

It is transformed into chemical energy by plants, which is then used by organisms and eventually lost as heat.

Question 3

In the third image, which molecule is oxidized and which is reduced during the light reactions of photosynthesis?

Accepted Answer

H$$_2O is $$oxidized to O$$_2$$, and NADP$$^+ is $$reduced to NADPH.

Question 4

Based on the fourth image, what is the main function of the thylakoid membrane in the light reactions?

Accepted Answer

To provide a surface for the electron transport chain and create a proton gradient for ATP synthesis.

Question 5

Referencing the fifth image, which wavelengths of light are most effective for photosynthesis and why?

Accepted Answer

Blue (around 440 nm) and red (around 680 nm) wavelengths are most effective because chlorophyll a and b absorb them strongly.

Question 6

Using the sixth image, which of the following correctly identifies the location of the Calvin cycle within the chloroplast?

Accepted Answer

The Calvin cycle occurs in the stroma.

Question 7

Which equation represents the overall process of photosynthesis?

Accepted Answer

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

Question 8

What would happen to ATP and NADPH production if water were not available to the chloroplast?

Accepted Answer

Both ATP and NADPH production would decrease because water is the source of electrons for Photosystem II.

Question 9

Which of the following best explains why the Calvin cycle is considered an anabolic pathway?

Accepted Answer

It uses ATP and NADPH to build larger molecules from smaller ones, such as synthesizing sugars from CO$$_2.$$

Question 10

If an herbicide blocks electron flow between Photosystem II and Photosystem I, what would be the effect on ATP and NADPH levels?

Accepted Answer

ATP levels would decrease, and NADPH levels would decrease because electron transport is required for both.

Question 11

Which structure in the chloroplast is directly responsible for the generation of a proton gradient used in ATP synthesis?

Accepted Answer

Thylakoid membrane

Question 12

How does increasing light intensity affect the rate of the light reactions up to a certain point?

Accepted Answer

The rate increases with light intensity until it reaches a plateau where other factors become limiting.

Question 13

Which of the following is a direct input to the Calvin cycle?

Accepted Answer

CO$$_2$$

Question 14

What is the primary purpose of the light reactions in photosynthesis?

Accepted Answer

To convert solar energy into chemical energy in the form of ATP and NADPH.

Question 15

Which environmental factor would most likely decrease the rate of the light reactions if it is outside the optimal range?

Accepted Answer

Increasing temperature beyond the optimal range for enzyme activity

Question 16

What is the role of ATP and NADPH in the Calvin cycle?

Accepted Answer

They provide energy and reducing power to convert CO$$_2$$ into sugar.

Question 17

If the supply of NADPH were interrupted, what would happen to the Calvin cycle?

Accepted Answer

The Calvin cycle would slow down or stop because NADPH is required for the reduction of CO$$_2.$$

Question 18

Which of the following best explains why treated weeds show yellow leaves after exposure to a herbicide that disrupts the light reactions?

Accepted Answer

The herbicide disrupts chlorophyll synthesis or function, reducing its ability to absorb light and causing yellowing.

Question 19

Which molecule is regenerated during the Calvin cycle to allow the cycle to continue?

Accepted Answer

RuBP

Step-by-Step Study Guide: Photosynthesis & Cellular Respiration

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