Question 1

Which process in the ecosystem converts light energy into chemical energy stored in organic molecules, as shown in the first diagram?

Accepted Answer

Photosynthesis in chloroplasts

Question 2

In glycolysis, which molecule is produced as the final product, and how many are generated per glucose molecule?

Accepted Answer

Pyruvate; 2

Question 3

During pyruvate oxidation, which of the following is a byproduct released, and what is the main purpose of this step?

Accepted Answer

CO$$_2$$; to link glycolysis to the citric acid cycle

Question 4

Which molecule enters the citric acid cycle, and how is it formed?

Accepted Answer

Acetyl CoA, formed from pyruvate oxidation

Question 5

What is the main function of the electron transport chain in mitochondria?

Accepted Answer

To create a proton gradient for ATP synthesis

Question 6

Which equation best represents the synthesis of ATP by ATP synthase during chemiosmosis?

Accepted Answer

$$\mathrm{ADP} + \mathrm{P_i} \rightarrow \mathrm{ATP} + \mathrm{H_2O}$$

Question 7

If oxygen is not present after glycolysis, what is the fate of pyruvate in human cells?

Accepted Answer

It is converted to lactate

Question 8

Which enzyme is regulated by ATP and citrate to inhibit glycolysis, as shown in the regulatory diagram?

Accepted Answer

Phosphofructokinase (PFK)

Question 9

What is the primary purpose of fermentation in cells?

Accepted Answer

To regenerate NAD$$^+$$ for glycolysis

Question 10

Which of the following best describes the difference between substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP; oxidative phosphorylation uses a proton gradient and ATP synthase

Question 11

Which metabolic pathway produces the most ATP per glucose molecule?

Accepted Answer

Oxidative phosphorylation

Question 12

What would happen to ATP production if NADH from glycolysis was missing?

Accepted Answer

ATP production would decrease because NADH is needed for the electron transport chain

Question 13

Which of the following is a correct summary of the inputs and outputs of the citric acid cycle per acetyl CoA?

Accepted Answer

Input: Acetyl CoA; Output: 2 CO$$_2$$, 3 NADH, 1 FADH$$_2$$, 1 ATP (or GTP)

Question 14

Which complex in the electron transport chain is responsible for the final reduction of oxygen to water?

Accepted Answer

Complex IV

Question 15

Why is it important for protons to accumulate on one side of the mitochondrial membrane during oxidative phosphorylation?

Accepted Answer

To create a proton gradient that powers ATP synthase

Question 16

If a poison blocks Complex I of the electron transport chain, which of the following would most likely occur?

Accepted Answer

NADH would accumulate and ATP production would decrease

Question 17

Which of the following best explains why NAD$$^+$$ must be regenerated during fermentation?

Accepted Answer

To allow glycolysis to continue producing ATP

Question 18

Which of the following is a product of alcoholic fermentation in yeast?

Accepted Answer

Ethanol

Question 19

Which equation represents the overall process of cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + \mathrm{O_2$} \rightarrow \mathrm{CO_2$} + \mathrm{H_2O} + \mathrm{ATP}$$

Question 20

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

Accepted Answer

It acts as an electron shuttle, accepting electrons and becoming NADH

Energy Flow and Cellular Respiration: Step-by-Step Study Guidance

Study Guide - Practice Questions