GED Science Life Science 3 — Questions and Answers
Question 1: Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?
- Ribosome
- Mitochondria (Correct answer)
- Golgi apparatus
- Endoplasmic reticulum
Correct answer: Mitochondria
Mitochondria are the site of cellular respiration, where glucose and oxygen are converted into ATP energy.
Question 2: A scientist observes that a population of moths shifts from mostly light-colored to mostly dark-colored after industrial pollution darkens tree bark. This is an example of:
- Genetic drift
- Founder effect
- Natural selection (Correct answer)
- Artificial selection
Correct answer: Natural selection
Natural selection favored dark moths because they were better camouflaged on soot-darkened trees and survived to reproduce more.
Question 3: Which of the following best describes the role of decomposers in an ecosystem?
- They convert sunlight into chemical energy
- They break down dead organisms and recycle nutrients (Correct answer)
- They transfer energy from plants to herbivores
- They fix nitrogen from the atmosphere
Correct answer: They break down dead organisms and recycle nutrients
Decomposers like fungi and bacteria break down dead organic matter, returning essential nutrients to the soil.
Question 4: In a DNA double helix, adenine always pairs with:
- Cytosine
- Guanine
- Thymine (Correct answer)
- Uracil
Correct answer: Thymine
Adenine pairs with thymine via two hydrogen bonds in DNA, following Chargaff's base-pairing rules.
Question 5: A plant is moved from a sunny window to a dark closet for two weeks. Which change would most likely occur first?
- Roots stop absorbing water
- Leaves turn yellow due to chlorophyll breakdown (Correct answer)
- Stomata permanently close
- The plant begins producing fruit
Correct answer: Leaves turn yellow due to chlorophyll breakdown
Without light, the plant cannot produce chlorophyll or use existing chlorophyll, causing leaves to yellow (chlorosis).
Question 6: Which process allows water to move from an area of low solute concentration to high solute concentration across a cell membrane?
- Active transport
- Diffusion
- Osmosis (Correct answer)
- Endocytosis
Correct answer: Osmosis
Osmosis is the passive movement of water across a semipermeable membrane from a region of lower solute concentration to higher solute concentration.
Question 7: Which level of biological organization is MOST inclusive?
- Organ system
- Tissue
- Population
- Ecosystem (Correct answer)
Correct answer: Ecosystem
An ecosystem includes all living organisms (populations, communities) plus their abiotic environment, making it the most inclusive level listed.
GED Science Life Science 3
Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?