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Natural Selection and Genetic Modification

Benefits and risks of GM organisms

  • 3 things to know
  • Paper 1

Overview

Crops given the Bacillus thuringiensis toxin gene and their advantages, pest resistance and other concerns about GM crops, the cost of GM seed, fertilisers and how run-off kills fish, biological control and its advantages and disadvantages, and calculating the percentage increase in yield.

What you need to know

Answer each one before you reveal it.

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Key term

Explain how a gene from Bacillus thuringiensis protects a crop plant.

Evaluation

Give two advantages of growing insect-resistant crop plants.

Key term

Explain why growing insect-resistant crops may harm other wildlife less than spraying insecticide does.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a genetically modified crop?

    Model answer

    It is a crop plant whose genome has had a gene added so that it shows a useful new characteristic.

  2. 2

    Which bacterium supplies the gene used to make crop plants resistant to insect pests?

    Model answer

    Bacillus thuringiensis.

  3. 3

    Explain how a gene from Bacillus thuringiensis protects a crop plant.

    Model answer

    The plant's cells make the bacterial toxin in their tissues, so insect larvae that feed on the crop are poisoned and die.

  4. 4

    Give two advantages of growing insect-resistant crop plants.

    Model answer

    Less of the crop is eaten so the yield is higher, and far less insecticide has to be sprayed onto the field.

  5. 5

    Explain why growing insect-resistant crops may harm other wildlife less than spraying insecticide does.

    Model answer

    The toxin only affects insects that actually eat the crop, whereas a spray drifts over a wide area and can kill harmless insects too.

  6. 6

    Suggest why insect pests may in time become resistant to the toxin made by an engineered crop.

    Model answer

    The pests meet the toxin constantly, so any individual with a resistance mutation survives, breeds and passes the allele on until resistance is common.

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Key Concepts in Biology
Cells and Control
Genetics
Natural Selection and Genetic Modification

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