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 primarily responsible for housing the light-capturing pigments?

Accepted Answer

Thylakoid membrane

Question 3

What is the main function of carotenoids in photosynthetic organisms?

Accepted Answer

To absorb blue and green light, extend the range of light absorption, and protect chlorophyll from damage

Question 4

During the Calvin cycle, which molecule acts as the initial reactant for carbon fixation?

Accepted Answer

Ribulose bisphosphate (RuBP)

Question 5

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

Accepted Answer

Rubisco; it is slow and can also catalyze a reaction with O$$_2$$ leading to photorespiration

Question 6

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

Accepted Answer

It would decrease because chlorophyll reflects green light rather than absorbing it

Question 7

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

Accepted Answer

Photosynthesis produces oxygen and carbohydrates, while cellular respiration consumes them

Question 8

A mutation causes a plant to lack a functional cuticle. What is the most likely consequence for the plant?

Accepted Answer

It will lose water rapidly and be unable to regulate gas exchange efficiently

Question 9

Which phase of the Calvin cycle directly uses ATP and NADPH produced by the light-capturing reactions?

Accepted Answer

Reduction phase

Question 10

Why do plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects and transmits green light, which is not absorbed

Question 11

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: $$E \propto \frac{1}{\lambda}$$

Question 12

Which of the following is a real-world consequence of photorespiration in crop plants under hot, dry conditions?

Accepted Answer

Reduced efficiency of photosynthesis due to Rubisco binding O$$_2$$ instead of CO$$_2$$

Question 13

What is the role of the stoma in plant leaves?

Accepted Answer

To allow CO$$_2 to $$diffuse into the leaf and O$$_2 to $$diffuse out

Question 14

Which of the following statements about the fate of G3P produced in the Calvin cycle is correct?

Accepted Answer

G3P can be used to make glucose and fructose, which may be combined to form sucrose or polymerized into starch

Question 15

A scientist measures the absorption spectrum of a plant pigment and finds strong absorption in the red and blue regions, but little in the green. Which pigment is most likely being measured?

Accepted Answer

Chlorophyll a or b

Question 16

Which part of the chlorophyll molecule is directly involved in absorbing light energy?

Accepted Answer

The head with a large ring structure containing a magnesium atom

Question 17

Which of the following regulatory mechanisms helps plants avoid unnecessary energy expenditure during photosynthesis?

Accepted Answer

Rubisco is activated by regulatory molecules only when light is available

Question 18

Which of the following best describes the role of accessory pigments in photosynthesis?

Accepted Answer

They absorb wavelengths of light not absorbed by chlorophyll and pass the energy to chlorophyll

Question 19

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

Accepted Answer

Rubisco will favor oxygenation, leading to increased photorespiration and decreased sugar production

Photosynthesis: Mechanisms, Structures, and Regulation

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