Unit 3- 1.2 Flashcards
What is a method of increasing food security?
One way is to develop new varieties of crops and livestock breeds using breeding programmes.
What do breeding programmes allow?
These programmes allow desirable features to be bred into particular plants and animals.
What are the desirable features in breeding programmes?
higher yields, higher nutritional values, pest and disease resistance, the ability the thrive in particular environmental conditions, and characteristics that assist rearing and harvesting.
What are dwarf varieties?
50 years ago, plant breeders discovered dwarf varieties of some cereal crops with much shorter stems than normal. These plants put more of their energy into creating seed and were easier to harvest, thus increasing the yield of these crops and improving food security.
What is inbreeding?
inbreeding involves crossing close relatives and is at its most intensive in naturally self-pollinating plants such as peas or wheat.
What does inbreeding ensure?
that offspring receive the alleles desired and eventually form a homozygous stock that will continue to breed true for the desired characteristic over many generations.
What is a disadvantage of inbreeding?
Is the deleterious recessive alleles also become homozygous. In nature this is avoided because natural selection eliminates individuals with harmful alleles.
It can be a problem in agriculture where natural selection is largely prevented or natural cross-breeders are forced to inbreed, and this is known as inbreeding depression.
What is outbreeding and it’s results?
Outbreeding involves crossing unrelated individuals, and occurs in animals and cross pollinating plants such as tomato and maize. Outbreeding maintains hetrozygosity and generally prevents the effects of inbreeding depression. However, offspring are varied and so not guaranteed to show the desired characteristics of their parents.
What is cross breeding and it’s results?
Breeders often deliberately maintain stock by cross breeding regularly. The F1 preforms well in the quality sought, but in most cases it is used for food because further breeding of hyrbids results in varied offspring.
What are test crosses?
These crosses can be used to identify animals carrying unwanted recessive alleles.
What are field trials?
They are controlled experiments to compare the performance of plots of different varieties of crop plant (cultivars) or how plots of one cultivar preform with a range of treatments such as different fertiliser application levels.
