CLEP Biology Molecular & Cellular Biology 2 — Questions and Answers
Question 1: Which enzyme is responsible for synthesizing RNA from a DNA template during transcription?
- DNA polymerase
- RNA polymerase (Correct answer)
- Reverse transcriptase
- Primase
Correct answer: RNA polymerase
RNA polymerase reads the DNA template strand and synthesizes a complementary RNA strand during transcription.
Question 2: What is the role of tRNA during translation?
- Carries the genetic code from the nucleus
- Provides the structural framework of the ribosome
- Delivers amino acids to the ribosome matching codons (Correct answer)
- Catalyzes peptide bond formation
Correct answer: Delivers amino acids to the ribosome matching codons
tRNA molecules carry specific amino acids and deliver them to the ribosome by anticodon-codon base pairing.
Question 3: Which of the following best describes a competitive inhibitor of an enzyme?
- It binds to the allosteric site and changes enzyme shape
- It permanently destroys the active site
- It binds to the active site and competes with the substrate (Correct answer)
- It increases the activation energy irreversibly
Correct answer: It binds to the active site and competes with the substrate
Competitive inhibitors bind reversibly to the active site, directly competing with the substrate for binding.
Question 4: In the fluid mosaic model of membranes, which molecules primarily form the bilayer?
- Glycoproteins
- Phospholipids (Correct answer)
- Cholesterol only
- Peripheral proteins
Correct answer: Phospholipids
Phospholipids arrange into a bilayer with hydrophilic heads facing outward and hydrophobic tails inward, forming the membrane's core structure.
Question 5: During which phase of the cell cycle does DNA replication occur?
- G1 phase
- S phase (Correct answer)
- G2 phase
- M phase
Correct answer: S phase
DNA replication takes place during the S (synthesis) phase of interphase, before mitosis begins.
Question 6: What type of cellular transport requires ATP and moves substances against their concentration gradient?
- Simple diffusion
- Facilitated diffusion
- Osmosis
- Active transport (Correct answer)
Correct answer: Active transport
Active transport uses ATP energy to pump molecules against their concentration gradient through specific carrier proteins.
Question 7: Which organelle is the primary site of ATP production via oxidative phosphorylation in eukaryotes?
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondria (Correct answer)
- Lysosome
Correct answer: Mitochondria
Mitochondria perform oxidative phosphorylation using the electron transport chain and ATP synthase to produce most cellular ATP.
CLEP Biology Molecular & Cellular Biology 2
Which enzyme is responsible for synthesizing RNA from a DNA template during transcription?