CLEP - Biology Cellular Respiration and Photosynthesis Questions and Answers

Question 1

Which of the following correctly describes a key difference between the Krebs cycle and the Calvin cycle?

Accepted Answer

The Krebs cycle is a catabolic pathway that produces ATP, while the Calvin cycle is an anabolic pathway that consumes ATP.

Answer

The Krebs cycle (part of cellular respiration) is a catabolic process because it breaks down molecules (acetyl-CoA) to release energy, producing ATP. In contrast, the Calvin cycle (part of photosynthesis) is an anabolic process because it uses energy (ATP and NADPH) to build larger molecules (sugars) from smaller ones (CO2).

Question 2

A scientist is studying a cell that has been treated with a chemical that makes the inner mitochondrial membrane permeable to protons (H+). Which of the following cellular processes would be most directly and severely affected?

Accepted Answer

Oxidative Phosphorylation

Answer

Oxidative phosphorylation relies on a proton gradient across the inner mitochondrial membrane to power ATP synthase. If this membrane becomes permeable to protons, the gradient will dissipate, and ATP synthase will be unable to produce large amounts of ATP. Glycolysis occurs in the cytoplasm and does not require a proton gradient. The Krebs cycle occurs in the mitochondrial matrix and while it provides electrons for the ETC, it is not directly inhibited by a leaky membrane. The Calvin Cycle is part of photosynthesis and occurs in chloroplasts.

Question 3

In the overall process of photosynthesis, the oxygen (O2) released comes from which molecule?

Accepted Answer

Water (H2O)

Answer

During the light-dependent reactions of photosynthesis, water molecules are split (a process called photolysis) to release electrons, protons (H+), and oxygen gas (O2). The oxygen is then released as a byproduct.

Question 4

Which of the following statements accurately compares the electron transport chains (ETCs) in cellular respiration and photosynthesis?

Accepted Answer

Both processes use the ETC to pump protons and generate a chemiosmotic gradient for ATP synthesis.

Answer

A primary function of the electron transport chain in both aerobic respiration (in mitochondria) and the light-dependent reactions of photosynthesis (in chloroplasts) is to use the energy from electron flow to pump protons across a membrane. This creates a proton gradient (chemiosmotic gradient) that drives the synthesis of ATP by ATP synthase.

Question 5

The primary function of the light-independent reactions (Calvin cycle) in photosynthesis is to:

Accepted Answer

Use ATP and NADPH to synthesize carbohydrates from carbon dioxide.

Answer

The Calvin cycle, also known as the light-independent reactions, uses the chemical energy (ATP and NADPH) produced during the light-dependent reactions to fix inorganic carbon (from CO2) into organic sugar molecules.

CLEP Practice Test

CLEP Practice Test

CLEP - Biology Cellular Respiration and Photosynthesis Questions and Answers