NYSTCE NYSTCE Biology (006) 4 — Questions and Answers
Question 1: Which process allows plants to convert light energy into chemical energy stored in glucose?
- Cellular respiration
- Photosynthesis (Correct answer)
- Fermentation
- Chemosynthesis
Correct answer: Photosynthesis
Photosynthesis uses light energy, water, and carbon dioxide to produce glucose and oxygen in chloroplasts.
Question 2: A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this?
- Missense mutation
- Silent mutation
- Nonsense mutation (Correct answer)
- Frameshift mutation
Correct answer: Nonsense mutation
UAA is a stop codon, so this change prematurely terminates translation, classifying it as a nonsense mutation.
Question 3: Which organelle is primarily responsible for detoxifying harmful substances in liver cells?
- Golgi apparatus
- Smooth endoplasmic reticulum (Correct answer)
- Rough endoplasmic reticulum
- Lysosome
Correct answer: Smooth endoplasmic reticulum
The smooth ER contains enzymes that detoxify drugs and other harmful compounds, and is especially abundant in liver cells.
Question 4: In a cross between two heterozygous individuals (Aa × Aa), what fraction of offspring are expected to be homozygous recessive?
- 1/4 (Correct answer)
- 1/2
- 3/4
- 1/8
Correct answer: 1/4
A Punnett square for Aa × Aa yields AA : Aa : aa in a 1:2:1 ratio, so 1/4 of offspring are homozygous recessive (aa).
Question 5: Which of the following best describes the role of decomposers in an ecosystem?
- They convert solar energy into chemical energy
- They break down dead organic matter and recycle nutrients (Correct answer)
- They transfer energy from producers to primary consumers
- They fix atmospheric nitrogen into ammonia
Correct answer: They break down dead organic matter and recycle nutrients
Decomposers such as bacteria and fungi break down dead organisms and return nutrients like nitrogen and phosphorus to the soil.
Question 6: During which phase of mitosis do sister chromatids separate and move to opposite poles?
- Prophase
- Metaphase
- Anaphase (Correct answer)
- Telophase
Correct answer: Anaphase
During anaphase, the spindle fibers shorten and pull sister chromatids apart toward opposite poles of the cell.
Question 7: A student observes that a population of bacteria becomes resistant to an antibiotic over several generations. Which mechanism best explains this observation?
- Lamarckian inheritance of acquired traits
- Natural selection acting on pre-existing genetic variation (Correct answer)
- Directed mutation induced by the antibiotic
- Horizontal gene transfer from eukaryotes
Correct answer: Natural selection acting on pre-existing genetic variation
Natural selection favors bacteria with pre-existing resistance mutations, causing resistant individuals to survive and reproduce more successfully.
NYSTCE NYSTCE Biology (006) 4
Which process allows plants to convert light energy into chemical energy stored in glucose?