Selective breeding: Disease resistance in food crops.

Q: How do I revise Selective breeding: Disease resistance in food crops. for GCSE?

Read the notes on Selective breeding: Disease resistance in food crops., then test yourself without looking. Answering questions and checking what you missed builds recall faster than re-reading.

Q: Is this Selective breeding: Disease resistance in food crops. guide aligned to the AQA specification?

Yes. This guide is linked to the Selective breeding: Disease resistance in food crops. topic in the AQA GCSE specification.

Disease resistance in food crops is a useful characteristic that breeders select for because resistant plants survive infection and produce a more reliable yield.

Study notes

From the checked teaching notes for this specification point.

The idea

What earns the marks

Disease resistance is a heritable characteristic that can be selected for in food crops.
Resistant plants survive disease better and give a more reliable yield for farmers.
Breeders cross resistant plants with plants showing other desirable features such as high yield.
Offspring showing resistance are selected and bred over several generations to increase resistance allele frequency.
Reduced disease loss can lower the need for chemical control measures.
Resistance is specific to particular pathogens and may be overcome if the pathogen changes.

Common mistakes and how to put them right

Saying resistant plants never get any disease.
Put it right by explaining resistance reduces the effect of a specific pathogen rather than giving total immunity to all diseases.
Ignoring yield while focusing only on resistance.
Put it right by noting that breeders usually combine resistance with high yield and other useful features.
Treating resistance as a single permanent feature.
Put it right by stating that pathogen populations can change and overcome resistance, so breeding is ongoing.

Exam tips

Link disease resistance to food security or reliable crop yield to show why it is useful.
Use the term pathogen when naming the organism that causes the disease.
Describe selection across generations rather than implying resistance appears immediately in one cross.

Try the lesson

The start of the Selective breeding: Disease resistance in food crops. lesson, made from checked teaching notes for this specification point.

Have a go first

A farmer wants a crop of wheat that is less likely to be killed by a fungal disease. Which parent plants should the farmer choose to breed from?

Tip: press 1 to 4 to choose

Listen

Disease resistance in food crops is a useful characteristic that breeders select for because resistant plants survive infection and produce a more reliable yield. Within a crop species, some individual plants naturally carry alleles giving resistance to a particular fungus, bacterium or virus. Breeders identify these plants, cross them with high-yielding plants, and then select offspring that show both resistance and good yield. This process is repeated over several generations. The result is a crop population in which resistance alleles are more common, so fewer plants are lost to disease and farmers may need fewer chemical treatments. Resistance is only effective against the specific pathogen concerned, and a new pathogen or a change in the pathogen population can overcome it. A strong answer earns marks for these points. Disease resistance is a heritable characteristic that can be selected for in food crops. Resistant plants survive disease better and give a more reliable yield for farmers. Breeders cross resistant plants with plants showing other desirable features such as high yield. Offspring showing resistance are selected and bred over several generations to increase resistance allele frequency. A common slip: Saying resistant plants never get any disease. Instead, explaining resistance reduces the effect of a specific pathogen rather than giving total immunity to all diseases. Exam tip: Link disease resistance to food security or reliable crop yield to show why it is useful.

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