Edexcel IGCSEBiologyGeneral Applications7 Marks
Genetic variation within a population is essential for natural selection.
- (a)State two sources of genetic variation within a species.[2]
- (b)Describe how natural selection leads to evolution.[5]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- 14(a) B1: mutation (1)
- B1: sexual reproduction / meiosis / independent assortment / crossing over / random fertilisation (1)
- 14(b) M1: individuals in a population show variation (1)
- M1: (due to mutation / sexual reproduction) (1)
- M1: struggle for existence / competition for resources (1)
- M1: those with advantageous / favourable alleles / characteristics are better adapted (to environment) (1)
- A1: (better adapted individuals) more likely to survive and reproduce (1)
- M1: pass on advantageous alleles / genes to offspring (1)
- A1: over many generations, frequency of advantageous alleles increases / population changes / evolution occurs (1)
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