9700 · 17.3
Evolution
Welcome to your premium revision deep dive into **Evolution** for Cambridge International A-Level Biology 9700 Paper 4! This fundamental topic explores how life on Earth has diversified, from the smallest bacteria to the most complex mammals. We'll cover the core principles of **natural selection**, the sources of **genetic variation**, how new species arise through **speciation**, and the population genetics of the **Hardy-Weinberg principle** and **genetic drift**. Get ready to connect these concepts to excel in your exams. Key points align with **A-Level Notes** 9700 Biology chapter **17** (topic **17.3**).
Need to know
What you need to know
- **Variation:** Individuals within a population show genetic variation (due to mutation, meiosis, random fertilisation).
- **Selection Pressure:** The environment exerts pressure (e.g., predation, disease, resource availability).
- **Differential Survival:** Individuals with advantageous phenotypes are better suited to survive and outcompete others.
- **Differential Reproduction:** These survivors are more likely to reproduce, passing on their advantageous alleles.
- **Inheritance:** Over generations, the frequency of these advantageous alleles increases in the population, leading to adaptation.
Explanation
Evolution
- **Variation:** Individuals within a population show genetic variation (due to mutation, meiosis, random fertilisation).
- **Selection Pressure:** The environment exerts pressure (e.g., predation, disease, resource availability).
- **Differential Survival:** Individuals with advantageous phenotypes are better suited to survive and outcompete others.
- **Differential Reproduction:** These survivors are more likely to reproduce, passing on their advantageous alleles.