Free CLEP Biology Exam Practice Questions

1. Enzymes catalyze biochemical reactions by

1. Lowering the potential energy of the products
2. Separating inhibitors from products
3. Forming a complex with the products
4. Lowering the activation energy of the reaction
5. Providing energy to the reaction

2. Which of the following is an example of a cofactor?

1. Zinc
2. Actin
3. Cholesterol
4. GTP
5. Chlorophyll

3. Cyanide is a poison that binds to the active site of the enzyme cytochrome c and prevents its activity. Cyanide is a(n):

1. Prosthetic group
2. Cofactor
3. Coenzyme
4. Inhibitor
5. Reverse regulator

4. The graph above shows the potential energy of molecules during the process of a chemical reaction. All of the following may be true EXCEPT

1. This is an endergonic reaction
2. The activation energy in curve 2 is less than the activation energy in curve 1
3. The energy of the products is less than the energy of the substrate
4. Curve 2 shows the reaction in the presence of an enzyme
5. The reaction required ATP

5. Which of the following is not a characteristic of enzymes?

1. They change shape when they bind their substrates
2. They can catalyze reactions in both forward and reverse directions
3. Their activity is sensitive to changes in temperature
4. They are always active on more than one kind of substrate
5. They may have more than one binding site

6. In a strenuously exercising muscle, NADH begins to accumulate in high concentration. Which of the following metabolic process will be activated to reduce the concentration of NADH?

1. Glycolysis
2. The Krebs cycle
3. Lactic acid fermentation
4. Oxidative phosphorylation
5. Acetyl CoA synthesis

7. Which of the following statements regarding chemiosmosis in mitochondria is not correct?

1. ATP synthase is powered by protons flowing through membrane channels
2. Energy from ATP is used to transport protons to the intermembrane space
3. Energy from the electron transport chain is used to transport protons to the intermembrane space
4. An electrical gradient and a pH gradient both exist across the inner membrane
5. The waste product of chemosmosis is water

8. In photosynthesis, high-energy electrons move through electron transport chains to produce ATP and NADPH. Which of the following provides the energy to create high energy electrons?

1. NADH
2. NADP+
3. O2
4. Water
5. Light

9. Which of the following kinds of plants is most likely to perform CAM photosynthesis?

1. Mosses
2. Grasses
3. Deciduous trees
4. Cacti
5. Legumes

10. The combination of DNA with histones is called

1. A centromere
2. Chromatin
3. A chromatid
4. Nucleoli
5. A plasmid

• CLEP Biology Exam Answer Key