EmSAT EmSAT Biology 3 — Questions and Answers
Question 1: What is natural selection?
- Random changes in DNA
- The process where organisms with favorable traits survive and reproduce more successfully (Correct answer)
- Artificial breeding of organisms
- The extinction of all species
Correct answer: The process where organisms with favorable traits survive and reproduce more successfully
Natural selection is the mechanism of evolution proposed by Darwin. Organisms with traits better suited to their environment survive and reproduce more, passing those advantageous traits to offspring.
Question 2: What is a mutation?
- A change in gene expression
- A permanent change in DNA sequence (Correct answer)
- The normal copying of DNA
- A type of cell division
Correct answer: A permanent change in DNA sequence
A mutation is a permanent change in the DNA sequence of an organism. Mutations can be beneficial, neutral, or harmful, and they are the ultimate source of genetic variation.
Question 3: What is biodiversity?
- The number of species in a single habitat
- The variety of life at genetic, species, and ecosystem levels (Correct answer)
- The study of ecosystems
- The rate of evolution
Correct answer: The variety of life at genetic, species, and ecosystem levels
Biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems. It encompasses the diversity of species, genetic variation within species, and variety of ecosystems.
Question 4: What is an ecosystem?
- A group of organisms of the same species
- A community of living organisms interacting with their non-living environment (Correct answer)
- The total number of genes in a species
- A single population of animals
Correct answer: A community of living organisms interacting with their non-living environment
An ecosystem consists of all the living organisms (biotic components) in an area, together with the non-living (abiotic) components (such as water, soil, and climate) with which they interact.
Question 5: What is the difference between a food chain and a food web?
- A food chain shows all connections; a food web shows one pathway
- A food chain shows one linear pathway of energy; a food web shows multiple interconnected pathways (Correct answer)
- They are the same thing
- A food web only includes plants
Correct answer: A food chain shows one linear pathway of energy; a food web shows multiple interconnected pathways
A food chain shows a single linear pathway of energy transfer from producer to consumers. A food web shows multiple interconnected food chains, representing the complex feeding relationships in an ecosystem.
Question 6: What role do decomposers play in an ecosystem?
- They produce energy from sunlight
- They consume living animals
- They break down dead organic matter and recycle nutrients (Correct answer)
- They fix nitrogen from the atmosphere only
Correct answer: They break down dead organic matter and recycle nutrients
Decomposers (fungi, bacteria) break down dead organic matter, recycling nutrients back into the ecosystem. They are essential for nutrient cycling and allow plants to reabsorb minerals.
EmSAT EmSAT Biology 3
What is natural selection?