Edexcel iGCSE Biology-4.33 Variation with a Species- Study Notes- New Syllabus
Edexcel iGCSE Biology-4.33 Variation with a Species- Study Notes- New syllabus
Edexcel iGCSE Biology-4.33 Variation with a Species- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
4.33 understand that variation within a species can be genetic, environmental, or a combination of both
Variation in a Species
🔹 Introduction
Variation = differences between individuals of the same species.
Makes every individual unique.
Can come from genes, environment, or both together.
📌 Types of Variation
- Genetic Variation (inherited)
Caused by differences in DNA. Passed from parents → offspring.
Examples: Eye colour, Blood group, Natural hair colour - Environmental Variation (acquired)
Caused by external conditions. Not inherited → does not pass to offspring.
Examples: Language spoken, Scars or injuries, Skin tan due to sunlight - Combination (Genetic + Environmental)
Many features are influenced by both genes & environment.
Examples: Height (genes set limit, diet affects growth), Weight (genes + lifestyle), Intelligence (genes + education/training)
📊 Summary Table
| Type of Variation | Cause | Examples |
|---|---|---|
| Genetic | Differences in DNA, inherited | Blood group, eye colour, freckles |
| Environmental | Conditions after birth | Accent, scars, sun-tan |
| Both (Combination) | Genes + environment | Height, weight, intelligence |
📝 Quick Recap
Variation = differences within a species.
3 sources:
Genetic → inherited, fixed (e.g., blood group).
Environmental → surroundings, not inherited (e.g., scars).
Combination → both genes & environment (e.g., height).
Variation = key for evolution & natural selection.