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CLEP Biology Free Sample Questions

12 free sample questions155 in the full practice test

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CLEP-BIOLOGY Sample Questions

  1. Question 1

    Beginner

    Molecular and Cellular Biology · Comparison of prokaryotic and eukaryotic cells

    A microbiologist isolates an uncharacterized unicellular microorganism from an alkaline hot spring. Which cellular feature definitively demonstrates that the organism is a eukaryote rather than a prokaryote?

    Answer and explanation

    Correct answer: C

    Eukaryotes uniquely compartmentalize genomic DNA within a membrane-bound nucleus, whereas prokaryotic genomes reside in an unbound nucleoid. All cells share ribosomes, membranes, and dsDNA.

  2. Question 2

    Intermediate

    Molecular and Cellular Biology · Structure and function of cell organelles

    Which eukaryotic organelle carries out the beta-oxidation of very long-chain fatty acids and contains catalase to decompose the resulting toxic hydrogen peroxide byproduct into water and oxygen?

    Answer and explanation

    Correct answer: D

    Peroxisomes perform fatty acid oxidation and neutralize toxic hydrogen peroxide into water and oxygen using catalase. Lysosomes degrade macromolecules via acidic hydrolases.

  3. Question 3

    Beginner

    Molecular and Cellular Biology · Properties of cell membranes

    True or False: In biological plasma membranes, integral transmembrane proteins are anchored within the phospholipid bilayer primarily by covalent bonds formed between fatty acid tails and amino acid side chains.

    Answer and explanation

    Correct answer: A

    Integral membrane proteins are anchored primarily by noncovalent hydrophobic interactions between nonpolar amino acid residues and the fatty acid core, not by covalent bonds.

  4. Question 4

    Intermediate

    Molecular and Cellular Biology · Inhibition and regulation

    An enzymologist evaluates an enzyme-catalyzed reaction in the presence of a chemical inhibitor. Increasing the substrate concentration progressively overcomes the inhibition, allowing the reaction to reach its original maximum velocity (Vmax), but the apparent Michaelis constant (Km) is increased.

    flowchart LR A["Free Enzyme + Substrate"] --> B["ES Complex"] B --> C["Free Enzyme + Product"] D["Reversible Inhibitor"] -.->|Competes for Catalytic Active Site| A
    Answer and explanation

    Correct answer: B

    Competitive inhibitors bind reversibly to the active site, increasing apparent Km without changing Vmax because excess substrate outcompetes the inhibitor.

  5. Question 5

    Beginner

    Molecular and Cellular Biology · Inorganic cofactors

    While organic non-protein helper molecules derived from vitamins are classified as coenzymes, essential inorganic ions such as magnesium (Mg2+) or zinc (Zn2+) required for optimal enzyme catalytic activity are classified as _____.

    Answer and explanation

    Correct answer: C

    Inorganic ions that assist enzyme function are termed cofactors, whereas organic non-protein helper molecules are called coenzymes.

  6. Question 6

    Intermediate

    Molecular and Cellular Biology · Glycolysis, cellular respiration, aerobic and anaerobic pathways

    During complete aerobic respiration of a glucose molecule in eukaryotic cells, which metabolic stage produces the greatest amount of ATP by coupling electron transport to chemiosmosis?

    Answer and explanation

    Correct answer: D

    Oxidative phosphorylation harnesses the proton gradient across the inner mitochondrial membrane via ATP synthase, producing about 90% of cellular ATP via chemiosmosis.

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