MTTC MTTC Biology 2 — Questions and Answers
Question 1: Which process converts glucose into pyruvate during cellular respiration?
- Glycolysis (Correct answer)
- Krebs cycle
- Oxidative phosphorylation
- Beta-oxidation
Correct answer: Glycolysis
Glycolysis occurs in the cytoplasm and converts one glucose molecule into two pyruvate molecules, yielding a net gain of 2 ATP.
Question 2: A student observes that a plant placed near a window grows toward the light. This response is called:
- Gravitropism
- Thigmotropism
- Phototropism (Correct answer)
- Hydrotropism
Correct answer: Phototropism
Phototropism is the directional growth of a plant in response to light, mediated by unequal distribution of auxin.
Question 3: Which type of RNA carries amino acids to the ribosome during translation?
- mRNA
- rRNA
- tRNA (Correct answer)
- snRNA
Correct answer: tRNA
Transfer RNA (tRNA) carries specific amino acids to the ribosome and uses its anticodon to match codons on mRNA.
Question 4: A population of beetles lives on light-colored bark. Over many generations, birds eat more dark beetles than light ones. This is an example of:
- Genetic drift
- Directional selection (Correct answer)
- Disruptive selection
- Stabilizing selection
Correct answer: Directional selection
Directional selection favors one extreme phenotype (light color) over others, shifting the population's average trait in one direction.
Question 5: Which organelle is primarily responsible for detoxifying harmful substances in liver cells?
- Lysosome
- Peroxisome (Correct answer)
- Golgi apparatus
- Vacuole
Correct answer: Peroxisome
Peroxisomes contain enzymes like catalase that break down hydrogen peroxide and other toxic molecules in liver and kidney cells.
Question 6: In an ecosystem, which trophic level has the greatest amount of energy available?
- Primary consumers
- Secondary consumers
- Producers (Correct answer)
- Decomposers
Correct answer: Producers
Producers (plants) occupy the base of the energy pyramid, capturing solar energy and containing the most total energy in the ecosystem.
Question 7: A mutation that changes a codon from UAC to UAA would most likely result in:
- A conservative amino acid substitution
- A frameshift mutation
- Premature termination of translation (Correct answer)
- Insertion of an incorrect amino acid
Correct answer: Premature termination of translation
UAA is a stop codon; changing UAC (tyrosine) to UAA causes translation to terminate prematurely, producing a truncated protein.
MTTC MTTC Biology 2
Which process converts glucose into pyruvate during cellular respiration?