Key Area 3.2 - Plant and animal breeding

why do we breed plants and animals

to improve characteristics and to help support sustainable food production

what do breeders develop crops and animals with

higher food yields

higher nutritional value

pest and disease resistance

ability to thrive in particular environmental conditions

what are plant field trials

experiments carried out in a range of environments to compare the performance of different cultivars or treatments and to evaluate GM crops

what needs to be taken into account when designing field trials

selection of treatments

the number of replicates

the randomisation of treatments

what does selection of treatments ensure

valid comparisons

what does the number of replicates account of

the variability within the sample

what is the purpose of the randomisation of treatments

to eliminate bias when measuring treatment effects

what happens in inbreeding

selected related plants or animals are bred for several generations until the population breeds true to the desired type due to the elimination of heterozygotes

what is a result of inbreeding

an increase in the frequency of individuals who are homozygous for recessive deleterious alleles. These individuals will do less well at surviving to reproduce. This results in inbreeding depression

how does crossbreeding in animals occur and what are its benefits

its when individuals from different breeds may produce a new crossbreed population with improved characteristics while the two parent breeds can be maintained to produce more crossbred animals showing the improved characteristic

how can new alleles can be introduced to plant and animal lines

by crossing a cultivar or breed with an individual with a different, desired genotype

in plants, how do F1 hybrids occur and what do they result in

produced by the crossing of two different inbred lines, create a relatively uniform heterozygous crop

what are traits of F1 hybrids

they often have increased vigour and yield

what are the positive outcomes for plants with increased vigour

they may have increased disease resistance or increased growth rate

In inbreeding animals and plants, why is it that F1 hybrids are not usually bred together

as the F2 produced would show too much genetic variation

what is a result of genome sequencing

organisms with desirable genes can be identified and then used in breeding programmes

what can breeding programmes involve

crop plants that have been genetically modified using recombinant DNA technology

what does recombinant DNA technology in plant breeding include

the insertion of Bt toxin gene into plants for pest resistance and the glyphosate resistance gene inserted for herbicide tolerance.

what can be inserted into the genomes of crop plants in recombinant DNA technology

Single genes for desirable characteristics can be inserted in order to create genetically modified plants with improved characteristics

what recombinant DNA technology techniques could improve crop plants

the use of agrobacterium