3.2 Plant and Animal Breeding Flashcards
Traditionally, new varieties of crops and livestock have been created by selective breeding. More recently, genetic manipulation has provided a more precise method of improving food production.
give examples of desired characteristics in plants and animals
Plants
- high grain yield in wheat
- environmentally tolerance
- disease resistance
- time of flowering/fruiting
- pest resistance
- wider environmental range
- specific nutrient concentration
Animals
- high milk yield in dairy cows
- size of animal
- litter/clutch size
- body composition (meat/fat)
- disease resistance
- higher nutritional value
describe ‘the words valid, accurate and reliable with examples’
Valid
- correct measurement have been taken to allow a conclusion to be drawn
- e.g. using dry mass, so that fluctuations in water content do not affect the result
Accurate
- the precision of the measurement (affected by apparatus)
- e.g. using a balance accurate to 2.dp instead of just 1.dp
Reliable
- how much you can trust the result (generally linked to replication, how many times you did the experiment)
- taking a large enough sample size/carrying out replicates and repeats
plant field trials are controlled experiments designed to:
- compare the performance of different treatments
- compare the performance of different cultivars
- evaluate GM (genetically modified) crops
what are the advantages of inbreeding?
populations will eventually breed true to the desired type due to the elimination of heterozygotes
describe ‘inbreeding depression’
Inbreeding can result in an issuer known as inbreeding depression.
Inbreeding depression is where there is an increase in the frequency of individuals who are homozygous for recessive deleterious alleles. These individuals are generally less able to survive to reproduce.
e.g. breeding of pedigree bulldogs
describe ‘cross breeding’
In order to introduce new alleles to a plant or animal line, selected individuals are crossed with another that shows the desired characteristic.
In animals, this is known as cross breeding and involve mating individuals from different breeds to produce a new crossbreed population that shows the desired traits from both parent breeds.
e.g. labradoodles — labrador/poodle crossbreed
why is it important to maintain both parent breeds when creating crossbreeds?
to produce more crossbred animals showing the improved characteristic
how are F1 hybrids created in plants?
by crossing two true-breeding lines to create a relatively uniform heterozygous crop
explain ‘why the high yielding, disease resistant wheat variety is produced by hybridising the disease resistant variety with the high yielding variety, instead of breeding two of the F1’s together
the F2 produced would show too much variation, and not be a uniform crop
describe ‘genetic technology’
desirable genes can be transferred from another species to a crop plant by Recombinant DNA Technology, to create genetically modified crop plants with improved characteristics. These individuals are then used in breeding programmes to produce entire crops with the desired characteristic.
e.g. bt toxin
how could organisms with desirable genes be identified for use in breeding programmes?
by using genome sequencing technology
