Question 1

Which of the following statements best describes the difference between autotrophs and heterotrophs?

Accepted Answer

Autotrophs produce their own organic molecules through photosynthesis, while heterotrophs obtain energy by consuming organic molecules produced by other organisms.

Question 2

During cellular respiration, which molecule acts as the final electron acceptor in aerobic respiration?

Accepted Answer

Oxygen ($$O_2)$$

Question 3

Which process directly produces ATP using the energy released from the transfer of a phosphate group from a substrate to ADP?

Accepted Answer

Substrate-level phosphorylation

Question 4

What is the net ATP yield from glycolysis per molecule of glucose?

Accepted Answer

$$2$$ ATP

Question 5

Which enzyme is allosterically inhibited by ATP and/or citrate during glycolysis, serving as a key regulatory point?

Accepted Answer

Phosphofructokinase

Question 6

In the Krebs cycle, for each acetyl-CoA that enters, how many NADH molecules are produced?

Accepted Answer

$$3$$ NADH

Question 7

Which of the following best explains why the electron transport chain (ETC) is essential for ATP production in aerobic respiration?

Accepted Answer

It creates a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis via ATP synthase.

Question 8

Which of the following equations correctly represents the hydrolysis of ATP and the associated change in free energy?

Accepted Answer

$$ATP + H_2O \rightarrow ADP + P_i$$; $$\Delta G = -7.3$$ kcal/mol

Question 9

During fermentation in muscle cells, which molecule is reduced to regenerate NAD$$^+$$?

Accepted Answer

Pyruvate

Question 10

Which of the following statements about the catabolism of fats is correct?

Accepted Answer

Fatty acids are broken down by beta-oxidation to form acetyl groups, which enter the Krebs cycle.

Question 11

Which of the following is NOT a product of ethanol fermentation in yeast?

Accepted Answer

Lactic acid

Question 12

In prokaryotes, where does the Krebs cycle occur?

Accepted Answer

Cytoplasm

Question 13

Which of the following is a correct sequence of the four stages of aerobic cellular respiration?

Accepted Answer

Glycolysis, Pyruvate oxidation, Krebs cycle, Electron transport chain

Question 14

Which molecule is produced during the deamination of alanine in protein catabolism and can enter cellular respiration?

Accepted Answer

Pyruvate

Question 15

A patient is suffering from muscle fatigue due to intense exercise. Which metabolic pathway is most likely responsible for the accumulation of lactic acid in their muscles?

Accepted Answer

Lactic acid fermentation

Question 16

Which of the following statements about NAD$$^+$$ and NADH is correct?

Accepted Answer

NADH is the reduced form, and NAD$$^+ is $$the oxidized form.

Question 17

Which of the following is a consequence of feedback inhibition in cellular respiration?

Accepted Answer

High levels of NADH inhibit pyruvate dehydrogenase.

Question 18

Which of the following is true regarding the energy yield from the complete oxidation of one glucose molecule in eukaryotes?

Accepted Answer

The net ATP yield is $$32$$ ATP molecules.

Question 19

Which of the following is a correct description of chemiosmosis?

Accepted Answer

The movement of protons down their concentration gradient through ATP synthase to generate ATP.

Question 20

In anaerobic respiration in prokaryotes, which of the following can serve as a final electron acceptor instead of oxygen?

Accepted Answer

Sulfur

Cellular Respiration: How Cells Harvest Energy

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