Grade 12 · CAPS

Grade 12 Evolution by Natural Selection

Life Sciences practice questions and a worked example

Grade 12 Evolution by Natural Selection covers Darwin's theory, artificial selection, speciation, reproductive isolation and the evidence for evolution. The questions here ask you to describe natural selection and apply it to examples such as wolves near Chernobyl and starvation resistance in fruit flies, explain artificial selection in mealies, explain how ratites on different continents became different species, and analyse investigations on variation. They come from the NSC Paper 2 for November 2023, 2024 and 2025: multiple-choice and terminology items from Section A and diagram, data and passage questions from Section B, each with the marking guideline's answer.

Worked example

3.1 The graph below shows the results of artificial selection for protein content in mealie plants over 50 generations. 3.1.1 Describe how this farmer did artificial selection of the mealie plant.

Answer

- The farmer interbred - mealie plants with a high protein content - over 50/many generations

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Evolution by Natural Selection

Question 1 of 3

1.2 Give the correct biological term for the following description. 1.2.2 The type of evolution characterised by long periods of little or no change followed by short periods of rapid change

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More practice questions

Explore additional Grade 12 Evolution by Natural Selection questions.

  • 2
    3.1 The graph below shows the results of artificial selection for protein content in mealie plants over 50 generations. 3.1.3 By how many times did the average percentage of the protein content in the mealie grains (kernels) increase between the 40th and 50th generation? Show ALL working.
  • 3
    3.1 The graph below shows the results of artificial selection for protein content in mealie plants over 50 generations. 3.1.4 Describe ONE way in which the process of artificial selection is different from genetic engineering.
  • 4
    3.2 Describe Darwin's theory of evolution by natural selection.
  • 5
    3.3 An investigation was done to determine the relationship between the height of the head and bite force in lizards. The procedure was as follows: • The scientists collected 120 lizards with similar characteristics that were around the same reproductive age in different habitats. • Their body characteristics and DNA were analysed to determine if they belonged to the same species. • 40 lizards belonged to species A, 36 to species B and 44 to species C. • Each species was kept in its cage with environmental conditions similar to their habitats. • The height of the head was measured for each lizard and averages calculated for each species. • Using a Kistler force, the bite force of each lizard in each species was measured five times and the average calculated for each lizard and each species. The results are shown in the table below. 3.3.1 Identify the: (b) Dependent variable

Common mistakes

  • Writing that organisms change because they need to. In Darwin's theory the variation is already there: those with the favourable characteristic survive, reproduce and pass the allele on.
  • Leaving out the last step of natural selection: the next generation has a higher proportion of individuals with the favourable characteristic.
  • Mixing up natural and artificial selection. In artificial selection humans choose which organisms breed; in natural selection the environment does.

More Grade 12 Life Sciences topics

Aligned to CAPS Grade 12 Life Sciences — Evolution by Natural Selection. Curriculum source: CAPS for the FET Phase, Department of Basic Education.

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