BS Bachelor of Science: Intro to Life Sciences 2 — Questions and Answers
Question 1: Which organelle is primarily responsible for ATP production through cellular respiration in eukaryotic cells?
- Ribosome
- Mitochondria (Correct answer)
- Golgi apparatus
- Lysosome
Correct answer: Mitochondria
Mitochondria carry out oxidative phosphorylation to produce the majority of a cell's ATP.
Question 2: During meiosis, crossing over (recombination) occurs between homologous chromosomes at which stage?
- Metaphase I
- Anaphase II
- Prophase I (Correct answer)
- Telophase II
Correct answer: Prophase I
Crossing over occurs during Prophase I when homologous chromosomes form bivalents and exchange segments.
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 DNA strands together.
Question 4: A population of bacteria doubles every 20 minutes. Starting with 100 cells, approximately how many cells are present after 1 hour?
- 400
- 600
- 800 (Correct answer)
- 1000
Correct answer: 800
After 3 doublings (60 min ÷ 20 min), the population is 100 × 2³ = 800 cells.
Question 5: Which process converts light energy into chemical energy stored in glucose?
- Cellular respiration
- Fermentation
- Photosynthesis (Correct answer)
- Glycolysis
Correct answer: Photosynthesis
Photosynthesis uses light energy to synthesize glucose from CO₂ and water in chloroplasts.
Question 6: In a food web, organisms that obtain energy by decomposing dead organic matter are called:
- Primary producers
- Herbivores
- Apex predators
- Decomposers (Correct answer)
Correct answer: Decomposers
Decomposers (fungi and bacteria) break down dead organic matter, recycling nutrients back into the ecosystem.
Question 7: Which molecule serves as the primary energy currency of the cell?
- NADH
- FADH₂
- ATP (Correct answer)
- Glucose
Correct answer: ATP
ATP (adenosine triphosphate) is the universal energy currency used to power cellular processes.
BS Bachelor of Science: Intro to Life Sciences 2
Which organelle is primarily responsible for ATP production through cellular respiration in eukaryotic cells?