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

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

Question 1

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

Accepted Answer

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

Question 2

Which structure within the chloroplast is the primary site of the light-capturing reactions of photosynthesis?

Accepted Answer

Thylakoid membrane

Question 3

A plant is exposed only to green light. Which of the following is most likely to occur?

Accepted Answer

The rate of photosynthesis will decrease because chlorophyll reflects green light.

Question 4

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

Accepted Answer

It uses ATP and NADPH to convert CO$$_2$$ into G3P.

Question 5

What is the main function of carotenoids in photosynthesis?

Accepted Answer

They absorb wavelengths of light not absorbed by chlorophyll and protect chlorophyll from damage.

Question 6

Which enzyme is responsible for the fixation of CO$$_2 in $$the Calvin cycle, and what is a key limitation of this enzyme?

Accepted Answer

Rubisco; it can also bind O$$_2$$, leading to photorespiration.

Question 7

A mutation causes a plant to lack a functional cuticle. Which of the following is the most likely consequence?

Accepted Answer

The plant will lose water rapidly and may dehydrate.

Question 8

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

Accepted Answer

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

Question 9

During the reduction phase of the Calvin cycle, which molecules are required to convert 3-phosphoglycerate (3PGA) into glyceraldehyde-3-phosphate (G3P)?

Accepted Answer

ATP and NADPH

Question 10

If a plant's stomata remain closed during the day to prevent water loss, what is the most likely effect on photosynthesis?

Accepted Answer

CO$$_2$$ entry is reduced, decreasing the rate of the Calvin cycle.

Question 11

Which of the following is a direct product of the light-capturing reactions of photosynthesis?

Accepted Answer

ATP and NADPH

Question 12

A scientist measures the absorption spectrum of a pigment and finds it absorbs strongly in the blue and red regions but not in the green. What pigment is this most likely to be?

Accepted Answer

Chlorophyll

Question 13

Which of the following best describes the fate of G3P produced by the Calvin cycle?

Accepted Answer

It can be used to synthesize glucose, fructose, and eventually starch or sucrose.

Question 14

Why is Rubisco considered both essential and inefficient for photosynthesis?

Accepted Answer

It catalyzes CO$$_2$$ fixation but also reacts with O$$_2$$, reducing efficiency.

Question 15

Which of the following is a real-world consequence of photorespiration in crop plants?

Accepted Answer

Reduced yield due to loss of fixed carbon and energy.

Question 16

A plant is genetically engineered to lack carotenoids. Which of the following would most likely occur under high light intensity?

Accepted Answer

Chlorophyll molecules would be damaged by free radicals.

Question 17

Which of the following best explains why almost every carbon atom in living organisms can be traced back to photosynthesis?

Accepted Answer

Photosynthesis is the primary process that converts inorganic CO$$_2$$ into organic molecules.

Question 18

Which of the following is a correct statement about the regulation of photosynthesis?

Accepted Answer

High sugar levels inhibit production of photosynthetic proteins.

Question 19

A plant cell is placed in an environment with very low CO$$_2$$ concentration. What is the most likely effect on Rubisco activity?

Accepted Answer

Rubisco will increasingly bind O$$_2$$, leading to more photorespiration.

Question 20

Which of the following best describes the relationship between the light-capturing reactions and the Calvin cycle?

Accepted Answer

The light-capturing reactions produce ATP and NADPH, which are used by the Calvin cycle to fix carbon.

Photosynthesis: Mechanisms and Significance in Biological Systems

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