CLEP Biology Molecular & Cellular Biology 4 — Questions and Answers
Question 1: What is the net gain of ATP molecules per glucose molecule during glycolysis alone?
- 4 ATP
- 2 ATP (Correct answer)
- 36-38 ATP
- 6 ATP
Correct answer: 2 ATP
Glycolysis yields 4 ATP but consumes 2 ATP in the investment phase, resulting in a net gain of only 2 ATP per glucose.
Question 2: Which of the following correctly describes the central dogma of molecular biology?
- RNA → DNA → Protein
- DNA → RNA → Protein (Correct answer)
- Protein → RNA → DNA
- DNA → Protein → RNA
Correct answer: DNA → RNA → Protein
The central dogma states that genetic information flows from DNA to RNA via transcription and then from RNA to protein via translation.
Question 3: Which type of bond holds the two strands of a DNA double helix together?
- Covalent bonds
- Ionic bonds
- Hydrogen bonds (Correct answer)
- Peptide bonds
Correct answer: Hydrogen bonds
Hydrogen bonds between complementary base pairs (A-T and G-C) hold the two antiparallel strands of DNA together.
Question 4: Sodium-potassium (Na⁺/K⁺) ATPase pumps maintain membrane potential by moving ions how?
- 3 Na⁺ in and 2 K⁺ out per cycle
- 2 Na⁺ out and 3 K⁺ in per cycle
- 3 Na⁺ out and 2 K⁺ in per cycle (Correct answer)
- 2 Na⁺ in and 2 K⁺ out per cycle
Correct answer: 3 Na⁺ out and 2 K⁺ in per cycle
The Na⁺/K⁺ ATPase expels 3 sodium ions out of the cell and imports 2 potassium ions per ATP hydrolyzed, creating an electrochemical gradient.
Question 5: Which cellular structure packages and modifies proteins for secretion?
- Rough endoplasmic reticulum
- Ribosome
- Golgi apparatus (Correct answer)
- Peroxisome
Correct answer: Golgi apparatus
The Golgi apparatus receives proteins from the ER, modifies them (e.g., glycosylation), sorts, and packages them into vesicles for secretion.
Question 6: What is the difference between chromatin and chromosomes?
- Chromosomes are found only in prokaryotes; chromatin only in eukaryotes
- Chromatin is loosely wound DNA-protein complex; chromosomes are condensed chromatin (Correct answer)
- Chromatin consists of RNA; chromosomes consist of DNA
- They are identical structures with different names
Correct answer: Chromatin is loosely wound DNA-protein complex; chromosomes are condensed chromatin
Chromatin is the decondensed DNA-histone complex found during interphase, while chromosomes are the highly condensed form visible during cell division.
Question 7: Which type of RNA carries the genetic information from the nucleus to the ribosome?
- rRNA
- tRNA
- mRNA (Correct answer)
- snRNA
Correct answer: mRNA
Messenger RNA (mRNA) is transcribed from DNA in the nucleus and carries the codon sequence to ribosomes in the cytoplasm for translation.
CLEP Biology Molecular & Cellular Biology 4
What is the net gain of ATP molecules per glucose molecule during glycolysis alone?