Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways break larger molecules into smaller ones and release energy; anabolic pathways build larger molecules from smaller ones and require energy.

Question 2

A scientist adds a large amount of substrate to an enzyme-catalyzed reaction and observes that the reaction rate increases at first but then levels off, even as more substrate is added. What is the most likely explanation for this observation?

Accepted Answer

All enzyme active sites are saturated with substrate, so the reaction rate cannot increase further.

Question 3

Which of the following equations correctly represents the change in free energy for a chemical reaction, and what does each term represent?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$, where $$\Delta G is $$free energy, $$\Delta H is $$enthalpy, $$T is $$temperature in kelvin, and $$\Delta S is $$entropy.

Question 4

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain, and what is formed as a result?

Accepted Answer

Oxygen, forming water

Question 5

Which of the following statements about ATP is correct?

Accepted Answer

ATP is a nucleotide composed of adenine, ribose, and three phosphate groups.

Question 6

A patient is exposed to a toxin that blocks the function of ATP synthase in mitochondria. Which of the following would most likely occur as a direct result?

Accepted Answer

ATP production by oxidative phosphorylation would decrease dramatically.

Question 7

Which of the following best explains why an organism is considered an open system?

Accepted Answer

It exchanges both energy and matter with its environment, such as taking in food and releasing heat and waste.

Question 8

Which process in cellular respiration is responsible for the direct transfer of a phosphate group from a substrate molecule to ADP, forming ATP?

Accepted Answer

Substrate-level phosphorylation

Question 9

A plant is exposed to only green light. What is the most likely effect on its rate of photosynthesis, and why?

Accepted Answer

Photosynthesis will decrease because green light is mostly reflected or transmitted, not absorbed.

Question 10

Which of the following best describes the role of NAD+ in cellular respiration?

Accepted Answer

It carries high-energy electrons from catabolic reactions to the electron transport chain.

Question 11

Which of the following is a major consequence of photorespiration in plants?

Accepted Answer

It uses energy and releases previously fixed CO2, reducing sugar production.

Question 12

Which adaptation allows C4 plants to minimize photorespiration?

Accepted Answer

They concentrate CO2 near rubisco using spatial separation of initial fixation and the Calvin cycle.

Question 13

Which of the following best describes the difference between linear (noncyclic) and cyclic electron flow in the light reactions of photosynthesis?

Accepted Answer

Linear flow produces ATP, NADPH, and O2; cyclic flow produces only ATP and no NADPH or O2.

Question 14

A mutation causes rubisco to bind O2 much more often than CO2. What is the most likely effect on the plant?

Accepted Answer

The plant will experience increased photorespiration, leading to less efficient carbon fixation.

Question 15

Which of the following correctly traces the movement of electrons during linear electron flow in photosynthesis?

Accepted Answer

H2O → Photosystem II → ETC → Photosystem I → NADP+

Question 16

Which of the following is a function of carotenoids in plant cells?

Accepted Answer

They absorb excess light energy and help dissipate it, protecting cells from damage.

Question 17

Which of the following best explains why the action spectrum for photosynthesis is broader than the absorption spectrum of chlorophyll a?

Accepted Answer

Accessory pigments such as chlorophyll b and carotenoids absorb additional wavelengths and transfer energy to chlorophyll a.

Question 18

Which of the following is a correct summary of the net ATP yield from the complete oxidation of one glucose molecule in cellular respiration?

Accepted Answer

About 30–32 ATP are produced, with most coming from oxidative phosphorylation.

Question 19

Which of the following best describes the role of the F0 portion of ATP synthase in mitochondria?

Accepted Answer

It forms a proton channel and rotor embedded in the membrane, allowing H+ to flow through.

Metabolism, Cellular Respiration, and Photosynthesis: Study Guide

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