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

Question 1

Which of the following statements best describes autotrophic organisms?

Accepted Answer

They produce organic molecules from CO$$_2$$ and inorganic substances using energy from sunlight or chemical reactions.

Question 2

During the light-dependent reactions of photosynthesis, which molecule acts as the primary electron acceptor in Photosystem II?

Accepted Answer

A specialized chlorophyll a molecule

Question 3

What is the overall balanced chemical equation for photosynthesis in plants?

Accepted Answer

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

Question 4

Which process in the chloroplast is directly responsible for the production of ATP during photosynthesis?

Accepted Answer

Chemiosmosis driven by the proton gradient across the thylakoid membrane

Question 5

In the Calvin cycle, what is the role of the enzyme Rubisco?

Accepted Answer

It catalyzes the fixation of CO$$_2 to a 5-$$carbon sugar (RuBP).

Question 6

Which of the following best explains why heterotrophic organisms depend on autotrophs?

Accepted Answer

Heterotrophs require organic molecules and oxygen produced by autotrophs for survival.

Question 7

Which step in the linear electron flow of photosynthesis directly results in the release of oxygen?

Accepted Answer

Splitting of water by Photosystem II

Question 8

A mutation disables the cytochrome complex in the thylakoid membrane. Which process would be most directly affected?

Accepted Answer

ATP synthesis via chemiosmosis

Question 9

Which of the following statements about photosynthetic pigments is correct?

Accepted Answer

Pigments are bound to proteins in light harvesting complexes and transfer energy to the reaction center.

Question 10

If a plant is exposed only to light with a wavelength of 750 nm, which photosynthetic process would be most affected?

Accepted Answer

Light absorption by chlorophyll a and b would be reduced, decreasing the efficiency of photosynthesis.

Question 11

How many ATP molecules are consumed for the synthesis of one molecule of G3P in the Calvin cycle?

Accepted Answer

$$9$$

Question 12

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

Accepted Answer

Glucose

Question 13

What is the main function of the proton gradient established across the thylakoid membrane?

Accepted Answer

To drive the synthesis of ATP via ATP synthase

Question 14

Which molecule is regenerated at the end of the Calvin cycle to allow the cycle to continue?

Accepted Answer

RuBP (ribulose-1,5-bisphosphate)

Question 15

A scientist measures the oxygen output of a plant under different light conditions. Under which condition would oxygen production be highest?

Accepted Answer

Exposure to visible light (380–750 nm)

Question 16

Which of the following best describes the role of NADP$$^+ in $$photosynthesis?

Accepted Answer

It acts as the final electron acceptor in the light-dependent reactions, forming NADPH.

Question 17

Which process occurs in the mitochondria and is analogous to chemiosmosis in chloroplasts?

Accepted Answer

ATP synthesis driven by a proton gradient across the inner mitochondrial membrane

Question 18

In the Calvin cycle, which phase involves the reduction of 3-phosphoglycerate to G3P?

Accepted Answer

Reduction phase, using NADPH and ATP

Question 19

A plant is genetically modified so that it cannot produce NADPH. Which process would be most directly affected?

Accepted Answer

Reduction of 3-phosphoglycerate to G3P in the Calvin cycle

Photosynthesis and Cellular Energy Conversion: Study Notes for General Biology

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