CIE IGCSE Biology

Topic Questions

18.1 Variation & Natural Selection

1
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What is a mutation?

  • A process used in genetic engineering.

  • A type of continuous variation.

  • A condition caused by a dominant allele.

  • A change in a gene.

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2
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Which of the following characteristics show discontinuous variation?

  • Length of foot

  • Weight

  • Tongue rolling

  • Height

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3
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Extended

Which of these is not a feature of a hydrophyte?

  • Roots and xylem reduced.

  • Large air spaces in the tissues.

  • Leaves rolled up and covered with hairs.

  • Leaves with stomata on the upper surface.

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4
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Which of the following is not a feature of natural selection?

  • Production of many offspring.

  • Selection by humans.

  • Competition for resources.

  • Variation in the population.

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5
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Which of these phenotypes is affected by both environmental and genetic factors?

  • Tongue rolling

  • Blood group

  • Weight

  • Gender

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The graph below shows the height of bean plants grown from 1000 bean seeds.

variation-graph

What variation do the plants show?

  • Discontinuous only.

  • Continuous only.

  • Neither continuous or discontinuous variation.

  • Both continuous and discontinuous variation.

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2
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A woman who has blood group A and a man who has blood group B have four children, each with a different blood group A, B, AB and O.

What variation does this show?

  • Discontinuous and genetic.

  • Continuous and genetic.

  • Continuous, environmental and genetic.

  • Discontinuous, environmental and genetic.

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Extended

Xerophytes have an inverted stomatal opening rhythm. This means that during the day when the sun is at its peak, most stomata of xerophytes are closed.

Which statement explains a disadvantage of this for the plant?

  • Less water is lost from plant. 

  • Less carbon dioxide can enter the plant.

  • Stomata only open at night.

  • Less oxygen can be lost from the plant. 

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4
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When growing millet, farmers choose seeds from high-yielding plants.

Which of the following is this an example of?

  • Evolution

  • Adaptation

  • Artificial selection

  • Natural selection

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5
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Which row best describes human blood groups?

 

affected by environment

has no intermediates

shows continuous variation

shows discontinuous variation

A

X

✓ 

X

✓ 

B

X

✓ 

✓ 

X

C

✓ 

X

✓ 

X

D

✓ 

X

X

✓ 

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An island’s entire population of a species of butterfly are descended from just two parents. These were introduced from the mainland.

Which of the following statements about this species of butterfly, compared with that of the mainland, is correct?

  • The population shows more genetic variety.

  • The population will adapt more slowly to environmental changes.

  • The population shows more phenotypic variation.

  • The population is less in danger of collapsing from disease.

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Extended

The diagram shows a hydrophyte in a stream.

hydrophyte

Which statement is true about the leaves underwater?

  • They offer little resistance to water flow.

  • They have a thick cuticle.

  • They require many xylem vessels for support.

  • They cannot photosynthesise.

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Extended

A patient with a bacterial infection is treated with antibiotics, but some of the bacteria survive.

Which statement is correct about the bacteria that have survived?

  • The bacteria will now be resistant to all antibiotics.

  • The resistant bacteria is a result of selective breeding.

  • The bacteria will have undergone a process of natural selection.

  • The antibiotic will now work better on the next generation of bacteria.

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Extended

A cactus is a type of xerophyte. Cacti have fewer stomata than other plants.

How is this an adaptation to survive in desert conditions?

  • It reduces loss of water.

  • It decreases the uptake of carbon dioxide.

  • It increases the uptake of carbon dioxide.

  • It increases the loss of water.

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Which of the following statements is a correct definition of ‘adaptive features’?

  • A change in the environment that is an advantage to an organism.

  • An inherited feature that increases an organism's ability to survive and reproduce.

  • A change in phenotype that is caused by the environment.

  • An action that aids an organism's ability to survive.

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