CLEP Natural Sciences Exam
Question 1. Which experiment demonstrated that amino acids could form under early Earth
conditions?
A) Griffith’s experiment
B) Hershey-Chase experiment
C) Miller-Urey experiment
D) Meselson-Stahl experiment
Answer: C
Explanation: The Miller-Urey experiment simulated early Earth conditions and showed that amino
acids could be synthesized from simple inorganic molecules, supporting the theory of abiogenesis.
Question 2. Which theory states that life originated from non-living matter?
A) Biogenesis
B) Abiogenesis
C) Panspermia
D) Endosymbiosis
Answer: B
Explanation: Abiogenesis is the concept that life arose naturally from non-living matter on early
Earth, as opposed to biogenesis (from existing life).
Question 3. What is considered the strongest evidence for evolution?
A) Fossil record
B) Weather patterns
C) Ocean currents
D) Plate tectonics
Answer: A
Explanation: The fossil record shows a chronological sequence of organisms and transitional forms,
providing strong evidence for evolution.
Question 4. Which mechanism of evolution involves random changes in allele frequencies due to
chance events?
A) Natural selection
B) Genetic drift
C) Gene flow
D) Mutation
Answer: B
Explanation: Genetic drift is the random fluctuation of allele frequencies in small populations, not
driven by fitness.
Question 5. What is the primary cause of speciation?
A) Mutation
B) Reproductive isolation
C) Genetic drift
D) Gene flow
Answer: B
Explanation: Speciation often occurs when populations become reproductively isolated, preventing
gene flow and leading to divergence.
Question 6. Two unrelated species independently evolve similar traits due to similar environments.
This is:
A) Divergent evolution
, CLEP Natural Sciences Exam
B) Convergent evolution
C) Coevolution
D) Adaptive radiation
Answer: B
Explanation: Convergent evolution describes the process where unrelated species develop similar
adaptations due to similar selective pressures.
Question 7. Which macromolecule is the main source of energy for most organisms?
A) Lipids
B) Proteins
C) Carbohydrates
D) Nucleic acids
Answer: C
Explanation: Carbohydrates, such as glucose, are the primary energy source for cellular processes.
Question 8. What property of water allows it to dissolve many substances?
A) Nonpolarity
B) High specific heat
C) Polarity
D) High density
Answer: C
Explanation: Water’s polarity enables it to dissolve various ionic and polar substances, making it a
universal solvent.
Question 9. Which macromolecule is composed of long chains of amino acids?
A) Carbohydrates
B) Lipids
C) Proteins
D) Nucleic acids
Answer: C
Explanation: Proteins are polymers made up of amino acid monomers linked by peptide bonds.
Question 10. Enzymes function by:
A) Increasing activation energy
B) Lowering activation energy
C) Being used up in reactions
D) Changing the products
Answer: B
Explanation: Enzymes are biological catalysts that lower the activation energy required for reactions,
speeding them up.
Question 11. Which organelle is responsible for energy production in eukaryotic cells?
A) Nucleus
B) Mitochondrion
C) Ribosome
D) Lysosome
Answer: B
Explanation: Mitochondria are known as the "powerhouses" of the cell, conducting cellular
respiration to produce ATP.
, CLEP Natural Sciences Exam
Question 12. Prokaryotic cells lack:
A) DNA
B) Ribosomes
C) Nucleus
D) Plasma membrane
Answer: C
Explanation: Prokaryotes (bacteria and archaea) lack a true nucleus; their DNA is found in the
nucleoid region.
Question 13. The first stage of cellular respiration is:
A) Krebs cycle
B) Oxidative phosphorylation
C) Glycolysis
D) Fermentation
Answer: C
Explanation: Glycolysis occurs in the cytoplasm and is the first step in breaking down glucose to
harvest energy.
Question 14. The main product of the light-dependent reactions of photosynthesis is:
A) Glucose
B) NADPH and ATP
C) Pyruvate
D) Oxygen only
Answer: B
Explanation: The light-dependent reactions produce ATP and NADPH, which are used in the Calvin
cycle to make glucose.
Question 15. Mitosis results in:
A) Four genetically different cells
B) Two genetically identical cells
C) One cell with twice the DNA
D) Four genetically identical cells
Answer: B
Explanation: Mitosis produces two daughter cells that are genetically identical to each other and the
parent cell.
Question 16. Which process moves molecules against their concentration gradient?
A) Simple diffusion
B) Facilitated diffusion
C) Osmosis
D) Active transport
Answer: D
Explanation: Active transport requires energy to move substances from low to high concentration.
Question 17. The law of segregation states that:
A) Genes are inherited together
B) Alleles separate during gamete formation
C) Only dominant traits are expressed
D) Genes are linked
Answer: B
, CLEP Natural Sciences Exam
Explanation: Mendel's law of segregation says that alleles for a gene separate during meiosis so each
gamete gets one allele.
Question 18. A cross between red and white flowers produces pink offspring. This is:
A) Complete dominance
B) Incomplete dominance
C) Codominance
D) Multiple alleles
Answer: B
Explanation: In incomplete dominance, the heterozygote shows an intermediate phenotype
between both parents.
Question 19. Blood type AB in humans is an example of:
A) Incomplete dominance
B) Codominance
C) Polygenic inheritance
D) Sex-linked inheritance
Answer: B
Explanation: Both A and B alleles are expressed equally in the phenotype, which is codominance.
Question 20. The chromosomal basis of inheritance was first demonstrated by:
A) Watson and Crick
B) Morgan’s fruit fly experiments
C) Miller-Urey experiment
D) Hershey-Chase experiment
Answer: B
Explanation: Thomas Hunt Morgan’s experiments with fruit flies established that genes are located
on chromosomes.
Question 21. Which of the following best describes the structure of DNA?
A) Single-stranded helix
B) Double-stranded helix
C) Triple-stranded helix
D) Linear chain
Answer: B
Explanation: DNA is a double helix composed of two antiparallel strands held together by hydrogen
bonds.
Question 22. During DNA replication, which enzyme unwinds the double helix?
A) Ligase
B) Helicase
C) DNA polymerase
D) RNA polymerase
Answer: B
Explanation: Helicase unwinds the DNA double helix, allowing replication to proceed.
Question 23. The process of making RNA from DNA is called:
A) Translation
B) Replication
C) Transcription
Question 1. Which experiment demonstrated that amino acids could form under early Earth
conditions?
A) Griffith’s experiment
B) Hershey-Chase experiment
C) Miller-Urey experiment
D) Meselson-Stahl experiment
Answer: C
Explanation: The Miller-Urey experiment simulated early Earth conditions and showed that amino
acids could be synthesized from simple inorganic molecules, supporting the theory of abiogenesis.
Question 2. Which theory states that life originated from non-living matter?
A) Biogenesis
B) Abiogenesis
C) Panspermia
D) Endosymbiosis
Answer: B
Explanation: Abiogenesis is the concept that life arose naturally from non-living matter on early
Earth, as opposed to biogenesis (from existing life).
Question 3. What is considered the strongest evidence for evolution?
A) Fossil record
B) Weather patterns
C) Ocean currents
D) Plate tectonics
Answer: A
Explanation: The fossil record shows a chronological sequence of organisms and transitional forms,
providing strong evidence for evolution.
Question 4. Which mechanism of evolution involves random changes in allele frequencies due to
chance events?
A) Natural selection
B) Genetic drift
C) Gene flow
D) Mutation
Answer: B
Explanation: Genetic drift is the random fluctuation of allele frequencies in small populations, not
driven by fitness.
Question 5. What is the primary cause of speciation?
A) Mutation
B) Reproductive isolation
C) Genetic drift
D) Gene flow
Answer: B
Explanation: Speciation often occurs when populations become reproductively isolated, preventing
gene flow and leading to divergence.
Question 6. Two unrelated species independently evolve similar traits due to similar environments.
This is:
A) Divergent evolution
, CLEP Natural Sciences Exam
B) Convergent evolution
C) Coevolution
D) Adaptive radiation
Answer: B
Explanation: Convergent evolution describes the process where unrelated species develop similar
adaptations due to similar selective pressures.
Question 7. Which macromolecule is the main source of energy for most organisms?
A) Lipids
B) Proteins
C) Carbohydrates
D) Nucleic acids
Answer: C
Explanation: Carbohydrates, such as glucose, are the primary energy source for cellular processes.
Question 8. What property of water allows it to dissolve many substances?
A) Nonpolarity
B) High specific heat
C) Polarity
D) High density
Answer: C
Explanation: Water’s polarity enables it to dissolve various ionic and polar substances, making it a
universal solvent.
Question 9. Which macromolecule is composed of long chains of amino acids?
A) Carbohydrates
B) Lipids
C) Proteins
D) Nucleic acids
Answer: C
Explanation: Proteins are polymers made up of amino acid monomers linked by peptide bonds.
Question 10. Enzymes function by:
A) Increasing activation energy
B) Lowering activation energy
C) Being used up in reactions
D) Changing the products
Answer: B
Explanation: Enzymes are biological catalysts that lower the activation energy required for reactions,
speeding them up.
Question 11. Which organelle is responsible for energy production in eukaryotic cells?
A) Nucleus
B) Mitochondrion
C) Ribosome
D) Lysosome
Answer: B
Explanation: Mitochondria are known as the "powerhouses" of the cell, conducting cellular
respiration to produce ATP.
, CLEP Natural Sciences Exam
Question 12. Prokaryotic cells lack:
A) DNA
B) Ribosomes
C) Nucleus
D) Plasma membrane
Answer: C
Explanation: Prokaryotes (bacteria and archaea) lack a true nucleus; their DNA is found in the
nucleoid region.
Question 13. The first stage of cellular respiration is:
A) Krebs cycle
B) Oxidative phosphorylation
C) Glycolysis
D) Fermentation
Answer: C
Explanation: Glycolysis occurs in the cytoplasm and is the first step in breaking down glucose to
harvest energy.
Question 14. The main product of the light-dependent reactions of photosynthesis is:
A) Glucose
B) NADPH and ATP
C) Pyruvate
D) Oxygen only
Answer: B
Explanation: The light-dependent reactions produce ATP and NADPH, which are used in the Calvin
cycle to make glucose.
Question 15. Mitosis results in:
A) Four genetically different cells
B) Two genetically identical cells
C) One cell with twice the DNA
D) Four genetically identical cells
Answer: B
Explanation: Mitosis produces two daughter cells that are genetically identical to each other and the
parent cell.
Question 16. Which process moves molecules against their concentration gradient?
A) Simple diffusion
B) Facilitated diffusion
C) Osmosis
D) Active transport
Answer: D
Explanation: Active transport requires energy to move substances from low to high concentration.
Question 17. The law of segregation states that:
A) Genes are inherited together
B) Alleles separate during gamete formation
C) Only dominant traits are expressed
D) Genes are linked
Answer: B
, CLEP Natural Sciences Exam
Explanation: Mendel's law of segregation says that alleles for a gene separate during meiosis so each
gamete gets one allele.
Question 18. A cross between red and white flowers produces pink offspring. This is:
A) Complete dominance
B) Incomplete dominance
C) Codominance
D) Multiple alleles
Answer: B
Explanation: In incomplete dominance, the heterozygote shows an intermediate phenotype
between both parents.
Question 19. Blood type AB in humans is an example of:
A) Incomplete dominance
B) Codominance
C) Polygenic inheritance
D) Sex-linked inheritance
Answer: B
Explanation: Both A and B alleles are expressed equally in the phenotype, which is codominance.
Question 20. The chromosomal basis of inheritance was first demonstrated by:
A) Watson and Crick
B) Morgan’s fruit fly experiments
C) Miller-Urey experiment
D) Hershey-Chase experiment
Answer: B
Explanation: Thomas Hunt Morgan’s experiments with fruit flies established that genes are located
on chromosomes.
Question 21. Which of the following best describes the structure of DNA?
A) Single-stranded helix
B) Double-stranded helix
C) Triple-stranded helix
D) Linear chain
Answer: B
Explanation: DNA is a double helix composed of two antiparallel strands held together by hydrogen
bonds.
Question 22. During DNA replication, which enzyme unwinds the double helix?
A) Ligase
B) Helicase
C) DNA polymerase
D) RNA polymerase
Answer: B
Explanation: Helicase unwinds the DNA double helix, allowing replication to proceed.
Question 23. The process of making RNA from DNA is called:
A) Translation
B) Replication
C) Transcription
