Truth in Science

Subject Criteria Section 3.17:

Selection and evolution can account for the diversity of living organisms

6105 Unit 5B: Genetics, evolution and biodiversity

5B.4

Sources of new inherited variation

recall the significance of meiosis and random fertilisation in sexual reproduction, in which gametes fuse to form a zygote, leading to genetic variation; understand that crossing-over leads to recombinant chromosomes; understand the significance of mutations; describe the effects of chemical mutagens and radiation; understand point mutations, illustrated by base deletions, insertions, substitutions; describe the effect of point mutation on amino acid sequences, as illustrated by sickle cell anaemia in humans; understand chromosome mutations, illustrated by translocation; understand that non-disjunction can lead to polysomy and polyploidy; Down’s syndrome.

Environmental change and evolution

understand natural selection; understand that selection pressures act on the gene pool and change allele frequency in the population; describe stabilising, directional and disruptive selection; understand that isolating mechanisms lead to the divergence of gene pools; understand geographical and behavioural isolating mechanisms; reproductive isolation; explain the difference between sympatric and allopatric speciation.