Chapter 9 / 5 short lessons
Variation, selection and species
Explain changes across generations by linking inherited variation to reproductive success, then test what the evidence can establish.
H1 Biology / 8876 / 2027 syllabus
What do you think?
An antibiotic is applied to a bacterial population. Must it create the exact resistance mutation that the bacteria need?
Lessons
0 of 5 marked as readSupply the variation selection needs
Explain why heritable variation from mutation, meiosis and sexual reproduction is needed for natural selection.
About 5 minExplain why an environment favours a variant
Use environmental examples to explain differential survival and reproduction.
About 5 minRead a change across generations
Explain evolution through natural selection and distinguish a population change from evidence for its cause.
About 5 minExplain why harmful alleles can persist
Explain preservation of genetic variation, including masking of recessive alleles and context-dependent heterozygote advantage.
About 5 minDecide what makes a biological species
Explain the biological species concept and apply its reproductive criterion with appropriate limits.
About 5 minWhat you will be able to do
- Explain where heritable variation comes from.
- Build a complete natural-selection explanation.
- Explain persistent variation and the biological species concept.