Increasing food production

OCR F212 AS Biology.

*Selective breeding: animals and plants (with examples).




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In 2000, a breeding programme began to produce a new, dwarf variety of
wheat that gives a higher yield than other dwarf varieties. Dwarf varieties
are more desirable because there is more wheat and less stem: if there
was more stem then energy would be used for growth on the stem rather
than production of wheat; farmers think this is a waste of energy.
The breeders of the programme chose to start with a high yield of dwarf
and the other with a not so good yield: the seeds. 48 plants were chosen
by their low height and fast flowering. 24 plants were chosen based on
their small flag leaf. 12 and 6 plants were based on their high yield. The 3
remaining plants breeded were compared to an earlier growth. This is
when the best line was chosen compared to an earlier growth line. This
is when the best line was chosen.
It took 10 generations for the dwarf wheat crops to be breeded.
The plants are identical so that they can harvest at the same time and the crops can stay healthy.
Leaf rust is a disease which affects wheat (in particular the area where photosynthesis takes place)
and is caused by a fungus. This becomes more apparent and frequent in warm and wet conditions;
this is the reason why this disease is particular common in Asia. Many of the varieties of wheat are
resistant to leaf rust. If two or more varieties have the same resistance genes then they could
become susceptible. If the rust fungus evolves, it can evade the defences. The best strategy is to
produce a variety with several different genes-this can lead to rust-resistant genes and even if it
combats one of these, it is very unlikely to affect all.
Aphids (they put their stylets in the phloem) take sucrose which means that there is less energy and so restrict growth and
yield. Also aphids often carry viruses that can infect the wheat which can cause diseases that weaken the plants and reduce
yields. Pesticides can be sprayed to kill them, yet this is expensive. There is a growing movement to go against pesticide use;
this is because it kills pests that are helpful, e.g. ladybirds
SELECTIVE BREEDING is where animals/ plants are breeded to enhance desirable characteristics; it depends on sex and carried
over several generations.
1. Identify the desired characteristic.
2. Select individuals which display desired characteristics.
3. Bred together/cross breed.
4. Allow offspring to develop to a stage where you can test or develop the characteristic.
Selective breeding is used to create better producing produce: higher yields of food and this leads to more money. Selective
breeding is not a new thing due to technology because it has been occurring over 10,000 years.
Types of produce:

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Disease resistant
Unfortunately, selective breeding exploits animals for meat, there is an ethical concern and it is narrowing the gene pool,
more chances of a mutation.
ARTIFICIAL INSEMINATION is selecting which sperm is likely to impregnate a female.
This can be frozen and kept for long periods.
The disadvantages of this are lameness (decreased mobility), increased vet bills, takes a long time, one disease could kill all
and can't guarantee characteristics.…read more


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