Question 1

Which of the following best describes the relationship between photosynthesis and cellular respiration as shown in the first image?

Accepted Answer

Photosynthesis stores energy in organic molecules, while cellular respiration releases that energy to produce ATP.

Question 2

During glycolysis (see image 2), what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 3

Referencing image 3, what are the products of pyruvate oxidation, and where does this process occur in the cell?

Accepted Answer

Acetyl CoA, CO$$_2$$, and NADH; in the mitochondrial matrix

Question 4

Which molecule enters the citric acid cycle (Krebs cycle) as shown in image 4, and what is its main function?

Accepted Answer

Acetyl CoA; to combine with oxaloacetate and drive the cycle that generates NADH, FADH$$_2$$, and ATP/GTP

Question 5

In the electron transport chain (image 5), what is the primary role of oxygen?

Accepted Answer

To act as the final electron acceptor, forming water

Question 6

According to image 6, how does ATP synthase produce ATP?

Accepted Answer

By using the flow of H$$^+$$ ions down their gradient to catalyze the conversion of ADP and P$$_i$$ into ATP

Question 7

Based on image 7, what determines whether pyruvate undergoes fermentation or enters the citric acid cycle?

Accepted Answer

The presence or absence of oxygen

Question 8

What is the role of phosphofructokinase (PFK) in glycolysis as shown in image 8, and how is it regulated?

Accepted Answer

It catalyzes a key regulatory step and is inhibited by ATP and citrate, but activated by AMP

Question 9

If the electron transport chain is inhibited (see image 9), what is the immediate effect on ATP production?

Accepted Answer

ATP production via oxidative phosphorylation stops, and the cell relies on substrate-level phosphorylation

Question 10

In alcoholic fermentation (image 10), what are the end products and why is NAD$$^+$$ regeneration important?

Accepted Answer

Ethanol and CO$$_2$$; NAD$$^+$$ regeneration allows glycolysis to continue producing ATP

Question 11

In lactic acid fermentation (image 11), what is the fate of pyruvate and why is this process critical during intense exercise?

Accepted Answer

Pyruvate is reduced to lactate, regenerating NAD$$^+ so $$glycolysis can continue producing ATP anaerobically

Question 12

According to the summary table (image 12), which step of cellular respiration produces the most ATP?

Accepted Answer

Oxidative phosphorylation

Question 13

If a poison blocks Complex I of the electron transport chain (see image 13), what would be the effect on NADH and FADH$$_2$$?

Accepted Answer

NADH cannot donate electrons, so its levels increase, while FADH$$_2$$ can still donate electrons at Complex II

Question 14

Which of the following best explains why iron is important in your diet for cellular respiration?

Accepted Answer

Iron is a cofactor in cytochromes of the electron transport chain, essential for electron transfer and ATP production

Question 15

What would happen if protons (H$$^+) $$could not flow back through ATP synthase (see image 6)?

Accepted Answer

ATP synthesis would stop because the proton gradient could not be used to power ATP synthase

Question 16

Which process is responsible for the majority of NAD$$^+$$ regeneration during aerobic respiration?

Accepted Answer

The electron transport chain

Question 17

If a cell is deprived of oxygen, which pathway will it rely on for ATP production, and why?

Accepted Answer

Fermentation, because it allows glycolysis to continue by regenerating NAD$$^+$$

Question 18

Which of the following is a correct description of substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP during glycolysis or the citric acid cycle

Question 19

Which of the following best explains why the breakdown of fats yields more ATP than carbohydrates?

Accepted Answer

Fats have more reduced carbon atoms, leading to more NADH and FADH$$_2$$ production for the electron transport chain

Energy Flow and Chemical Recycling in Ecosystems (Figure 7.2)

Study Guide - Practice Questions