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 what is the net gain of ATP per glucose molecule?

Accepted Answer

Pyruvate; 2 ATP

Question 3

During pyruvate oxidation, which molecules are produced and what is the significance of NAD+ in this process?

Accepted Answer

Acetyl CoA and CO$$_2$$; NAD+ is reduced to NADH, carrying electrons to the electron transport chain

Question 4

Which equation best represents the overall process of cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\,O_2$ \rightarrow 6\,CO_2$ + 6\,H_2O + ATP$$

Question 5

What is the main purpose of the citric acid cycle (Krebs cycle) in cellular respiration?

Accepted Answer

To generate NADH and FADH$$_2$$ for the electron transport chain

Question 6

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

Accepted Answer

Acetyl CoA; formed from pyruvate oxidation

Question 7

In the electron transport chain, what is the role of oxygen?

Accepted Answer

It acts as the final electron acceptor, forming water

Question 8

How does ATP synthase produce ATP during oxidative phosphorylation?

Accepted Answer

By using the energy from the proton gradient to combine ADP and inorganic phosphate ($$P_i)$$

Question 9

What would happen if protons did not move through ATP synthase to the other side of the mitochondrial membrane?

Accepted Answer

ATP production would stop because the energy from the proton gradient would not be harnessed

Question 10

Which enzyme is responsible for making ATP during chemiosmosis?

Accepted Answer

ATP synthase

Question 11

If oxygen is not present after glycolysis, what happens to pyruvate in human cells?

Accepted Answer

It is converted to lactate through fermentation

Question 12

Why is NAD+ regeneration important during fermentation?

Accepted Answer

It allows glycolysis to continue by accepting electrons

Question 13

Which of the following best describes feedback inhibition in cellular respiration?

Accepted Answer

High levels of ATP inhibit phosphofructokinase, slowing glycolysis

Question 14

Which pathway produces the most ATP per glucose molecule?

Accepted Answer

Oxidative phosphorylation

Question 15

What is the main purpose of fermentation in yeast?

Accepted Answer

To regenerate NAD+ and produce ethanol

Question 16

Which of the following is a product of fermentation in human muscle cells?

Accepted Answer

Lactate

Question 17

How do fats and proteins enter cellular respiration to be used for energy?

Accepted Answer

Fats are broken down into acetyl CoA, and proteins are converted into intermediates of glycolysis or the citric acid cycle

Question 18

Which of the following statements about the electron transport chain is correct?

Accepted Answer

It uses NADH and FADH$$_2 to $$create a proton gradient across the mitochondrial membrane

Question 19

If a poison blocks Complex I of the electron transport chain, what would be the immediate effect on cellular respiration?

Accepted Answer

NADH cannot be oxidized, leading to decreased ATP production

Question 20

Which equation represents the synthesis of ATP by ATP synthase?

Accepted Answer

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

Energy and Enzymes: Cellular Respiration, Photosynthesis, and Metabolic Pathways

Study Guide - Practice Questions