CLEP Biology Molecular & Cellular Biology 3 — Questions and Answers
Question 1: Which of the following nitrogenous bases is found in RNA but NOT in DNA?
- Adenine
- Cytosine
- Uracil (Correct answer)
- Guanine
Correct answer: Uracil
RNA contains uracil instead of thymine; uracil pairs with adenine just as thymine does in DNA.
Question 2: What is the function of the smooth endoplasmic reticulum (SER)?
- Protein synthesis via ribosomes
- Lipid synthesis and detoxification (Correct answer)
- Processing and sorting proteins for secretion
- Digesting cellular debris
Correct answer: Lipid synthesis and detoxification
The smooth ER lacks ribosomes and is specialized for lipid synthesis, steroid hormone production, and detoxification of drugs.
Question 3: Which process produces NADH and pyruvate from glucose without oxygen?
- Oxidative phosphorylation
- Glycolysis (Correct answer)
- The citric acid cycle
- Beta-oxidation
Correct answer: Glycolysis
Glycolysis occurs in the cytoplasm and breaks down one glucose molecule into two pyruvate molecules, generating 2 ATP and 2 NADH.
Question 4: In prokaryotes, DNA is located in which region of the cell?
- Nucleus
- Mitochondria
- Nucleoid region (Correct answer)
- Endoplasmic reticulum
Correct answer: Nucleoid region
Prokaryotes lack a membrane-bound nucleus; their circular DNA resides in an irregularly shaped nucleoid region in the cytoplasm.
Question 5: Which macromolecule serves as the primary structural component of the cell wall in bacteria?
- Cellulose
- Chitin
- Peptidoglycan (Correct answer)
- Glycogen
Correct answer: Peptidoglycan
Bacterial cell walls are composed of peptidoglycan, a mesh-like polymer of sugars and amino acids that provides rigidity.
Question 6: What is the term for the entire set of proteins expressed by a cell at a given time?
- Genome
- Transcriptome
- Metabolome
- Proteome (Correct answer)
Correct answer: Proteome
The proteome refers to the complete set of proteins expressed by a cell, tissue, or organism under specific conditions.
Question 7: Which stage of mitosis is characterized by chromosomes aligning at the cell's equatorial plate?
- Prophase
- Anaphase
- Metaphase (Correct answer)
- Telophase
Correct answer: Metaphase
During metaphase, chromosomes are maximally condensed and align along the metaphase plate before sister chromatids are separated.
CLEP Biology Molecular & Cellular Biology 3
Which of the following nitrogenous bases is found in RNA but NOT in DNA?