Study Notes
Variation refers to the differences between individuals of the same species.
- Phenotypic Variation — differences in features between individuals of the same species. Example: Height differences among humans.
- Genetic Variation — differences caused by differences in genes. Example: Blood type in humans.
- Continuous Variation — when there are many small degrees of difference for a characteristic, often influenced by both genes and environment. Example: Human height.
- Discontinuous Variation — distinct differences for a characteristic, usually caused by genes alone. Example: Blood groups A, B, AB, and O.
- Mutation — a change in a gene or chromosome. Example: Sickle cell anemia caused by a genetic mutation.
Exam Tips
Key Definitions to Remember
- Variation: Differences between individuals of the same species.
- Phenotypic Variation: Differences in features between individuals.
- Genetic Variation: Differences caused by genes.
- Continuous Variation: Range of phenotypes between two extremes.
- Discontinuous Variation: Limited number of distinct phenotypes.
- Mutation: Change in a gene or chromosome.
Common Confusions
- Confusing continuous and discontinuous variation.
- Believing all variations are genetic when some are environmental.
Typical Exam Questions
- What is continuous variation? Continuous variation is influenced by genes and environment, resulting in a range of phenotypes.
- What causes discontinuous variation? Discontinuous variation is caused by genes alone.
- How can mutations affect an organism? Mutations can have positive, negative, or no effects on an organism.
What Examiners Usually Test
- Understanding the difference between continuous and discontinuous variation.
- Examples of genetic and environmental influences on variation.
- Effects and causes of mutations.