Biology Test Biology Biochemistry & Metabolism 2 — Questions and Answers
Question 1: The Krebs cycle occurs in which part of the mitochondria?
- Outer membrane
- Intermembrane space
- Matrix (Correct answer)
- Inner membrane
Correct answer: Matrix
The Krebs (citric acid) cycle takes place in the mitochondrial matrix where its enzymes are dissolved.
Question 2: Which type of bond links amino acids together in a protein?
- Glycosidic bond
- Phosphodiester bond
- Peptide bond (Correct answer)
- Hydrogen bond
Correct answer: Peptide bond
Peptide bonds form between the carboxyl group of one amino acid and the amino group of the next during protein synthesis.
Question 3: Beta-oxidation is the metabolic process that breaks down:
- Carbohydrates
- Proteins
- Nucleic acids
- Fatty acids (Correct answer)
Correct answer: Fatty acids
Beta-oxidation sequentially cleaves two-carbon units from fatty acid chains, generating acetyl-CoA for the Krebs cycle.
Question 4: Competitive inhibition of an enzyme can be overcome by:
- Decreasing pH
- Adding more inhibitor
- Increasing substrate concentration (Correct answer)
- Lowering temperature
Correct answer: Increasing substrate concentration
In competitive inhibition, increasing substrate concentration outcompetes the inhibitor for the active site, restoring enzyme activity.
Question 5: Which vitamin is a precursor to the coenzyme NAD+?
- Vitamin C
- Vitamin B3 (Niacin) (Correct answer)
- Vitamin D
- Vitamin B12
Correct answer: Vitamin B3 (Niacin)
Niacin (vitamin B3) is the dietary precursor used by cells to synthesize NAD+ and NADP+.
Question 6: Gluconeogenesis is the metabolic pathway that synthesizes glucose from:
- Fatty acids only
- Non-carbohydrate precursors such as lactate and amino acids (Correct answer)
- Glycogen only
- Pyruvate via glycolysis
Correct answer: Non-carbohydrate precursors such as lactate and amino acids
Gluconeogenesis uses non-carbohydrate substrates like lactate, glycerol, and glucogenic amino acids to produce glucose, mainly in the liver.
Biology Test Biology Biochemistry & Metabolism 2
The Krebs cycle occurs in which part of the mitochondria?