Summary
Variation and selection are key concepts in understanding how species adapt and evolve over time. Mutation — a change in a gene or chromosome. Example: A mutation can lead to genetic variation or disorders. Discontinuous Variation — traits with distinct categories. Example: Tongue rolling is a trait where individuals can either roll their tongue or not. Continuous Variation — traits that vary gradually across a range. Example: Height in humans varies due to genetic and environmental factors. Natural Selection — process where organisms better adapted to their environment tend to survive and reproduce. Example: Bacteria developing resistance to antibiotics through natural selection. Artificial Selection — human-controlled process of breeding for specific traits. Example: Breeding crops for higher yield.
Exam Tips
Key Definitions to Remember
- Mutation: A change in a gene or chromosome.
- Discontinuous Variation: Traits with distinct categories.
- Continuous Variation: Traits that vary gradually across a range.
- Natural Selection: Survival and reproduction of organisms better adapted to their environment.
- Artificial Selection: Human-controlled breeding for specific traits.
Common Confusions
- Mutation vs. Genetic Engineering: Mutations occur naturally, while genetic engineering is human-controlled.
- Continuous vs. Discontinuous Variation: Continuous variation shows a range, while discontinuous has distinct categories.
Typical Exam Questions
- What is an example of discontinuous variation? Tongue rolling.
- How does natural selection lead to antibiotic resistance in bacteria? Bacteria with resistance survive and reproduce, passing on the trait.
- What is artificial selection? Selection by humans for specific traits in organisms.
What Examiners Usually Test
- Understanding of mutation and its role in genetic variation.
- Differences between continuous and discontinuous variation.
- Examples and implications of natural and artificial selection.