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Sexual Reproduction in Plants

Pollination and double fertilisation

  • 3 things to know
  • Component 2

Overview

Two structural features that make self-pollination unlikely in a flower, how the pollen tube grows down through the style and two fusions that make up double fertilisation.

What you need to know

Answer each one before you reveal it.

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Key term

What prevents a plant from pollinating itself, and what happens in double fertilisation?

Key term

Define pollination.

Evaluation

Give one advantage of self-pollination.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define pollination.

    Model answer

    Pollination is the transfer of pollen from an anther to a stigma.

  2. 2

    Distinguish self-pollination from cross-pollination.

    Model answer

    In self-pollination pollen reaches a stigma on the same plant, whereas in cross-pollination it reaches a stigma on a different plant of the same species.

  3. 3

    Give one genetic advantage of cross-pollination.

    Model answer

    It combines alleles from two different plants, so the offspring are more variable and the population is better able to adapt to change.

  4. 4

    Give one advantage of self-pollination.

    Model answer

    An isolated plant can still set seed even when no pollinator visits and no other plant of the species is nearby.

  5. 5

    Give one disadvantage of self-pollination.

    Model answer

    It reduces genetic variation, so harmful recessive alleles become homozygous more often and the offspring are less able to adapt.

  6. 6

    Name two structural features that make self-pollination unlikely in a flower.

    Model answer

    The stigma may be held well above the anthers, and a plant may carry flowers of only one sex.

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