Cambridge IGCSE Biology, topic 18
Variation and selection
Variation and selection looks at why individuals of the same species are different, where new alleles come from and how the environment shapes which individuals survive. It covers natural selection, adaptive features, and how humans use selective breeding to improve crops and animals. Extended candidates also explain adaptation, hydrophytes and xerophytes, and antibiotic-resistant bacteria.
Revision notes
Worksheet
FlashcardsSubtopics
Work through them in order. Each one has notes, exam questions and flashcards, and a PDF of each.
- 1Variation Spec 18.1.1–18.1.10Continuous and discontinuous variation, what causes them, and how mutation and other processes create genetic variation.NotesQuestions 7Flashcards 9
- 2Adaptive features Spec 18.2.1–18.2.3Adaptive features as inherited features that aid survival and reproduction, with hydrophyte and xerophyte examples.NotesQuestions 6Flashcards 6
- 3Selection Spec 18.3.1–18.3.6Natural selection and adaptation, antibiotic-resistant bacteria, selective breeding and how natural and artificial selection differ.NotesQuestions 7Flashcards 9
Whole topic
When you have done the subtopics: test yourself on everything, or print the lot.