They are found at the start of food chains and convert sunlight energy into chemical energy (glucose) in organic molecules. This is used for plant growth, which can then be eaten by animals.
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What does genetic engineering allow us to do?
Introduce single genes into crop species to improve their characteristics. However, most characteristics are caused by many genes.
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What is selective breeding?
The intentional breeding of certain characteristics or combination of characteristics to increase the benefit to humans.
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What are the stages of selective breeding?
Isolation. Artificial selelction. Inbreeding or line breeding.
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Why would a breeding a dwarf wheat variety be more cost-effective?
We want the grain for flour. The stalk has limited value. Dwarf wheat means less stalk, so more energy goes into grain production, so less money wasted. It'll stand up better and won't fall down or get crushed.
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How do farmers produce dwarf wheat which is also high yielding?
The breeders start with a very small dwarf variety which wasn't very high yielding, with one that isn't dwarf but was high-yielding.
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How does selective breeding work?
With each generation of offspring, the best ones are selected to breed with again and again. The poorer ones are rejected. Over time, the plants are being selected for their dwarfness and high yield until a good enough result is achieved.
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How was the leaf-rust resistant wheat variety produced?
Many wheat varieties in Asia have some resistance to leaf rust. If they had the same resistance genes, it would leave them vulnerable. Best strategy's to produce a variety with different resistant genes. The rust is unlikely to overcome them all.
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Why is DNA technology so useful?
It can be used to detect particular genes in a plant, so plants that have several of the rust-resistant genes can be identified more easily.
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How do Russian wheat aphids cause damage to plants?
They push their needle-like mouthparts into the phloem & withdraw the sap. So the plant loses sugars and has less energy for growth. Aphids can also carry viral infections in their mouthparts, which can kill the plant.
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Why are pesticides not used to kill aphids?
The pesticides are harmful to beneficial insects, and they are expensive.
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How is wheat which is resistant to the Russian wheat aphid produced?
Two resistant plants are chosen and cross-pollinated. The resulting seeds are collected and sown. When the new plants are grown, those with good resistance are selected, two of these are crossed, and so this process continues.
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Give 2 examples of good meat-producing cow breeds.
Hereford, Aberdeen Angus.
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Give 2 examples of good milk-producing cow breeds.
Friesians, Jerseys.
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How are cattle bred for high meat productivity?
Bulls with lots of muscle are chosen as sires, and only the largest cows are used for breeding. Semen is collected from chosen bulls and then used for artificial insemination.
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How are cattle bred for high milk productivity?
Bulls are chosen whose female relatives have high milk yields and who are known to produce calves that have a high milk yield.
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Why must care be taken with these breeding programmes?
To avoid the health of the cattle being compromised. Cattle that produce more milk are more likely to suffer from mastitis and lameness. Vet bills for these can be expensive.
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Other cards in this set
Card 2
Front
What does genetic engineering allow us to do?
Back
Introduce single genes into crop species to improve their characteristics. However, most characteristics are caused by many genes.
Card 3
Front
What is selective breeding?
Back
Card 4
Front
What are the stages of selective breeding?
Back
Card 5
Front
Why would a breeding a dwarf wheat variety be more cost-effective?
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