3.2 Plant and Animal Breeding Flashcards
characteristics that breeders develop crops and animals with (4)
- higher food yields
- higher nutritional values
- pest & disease resistance
- the ability to thrive in particular environmental conditions
why are plant field trials carried out in a range of environments? (2)
- to compare the performance or different cultivars or treatments
- to evaluate GM crops
factors which have to be taken account of when designing field trials (3)
- the selection of treatments
- the number of replicates
- the randomisation of treatments
why the selection of treatments has to be taken account of when designing field trials
to ensure valid comparisons
why the number of replicates has to be taken account of when designing field trials
to take account of variability within the sample
why the randomisation of treatments has to be taken account of when designing field trials
to eliminate bias when measuring treatment effects
inbreeding
when selected related plants or animals are bred together for several generations until the population breeds true to the desired type
in inbreeding, why does the breeding of related plants or animals together result in the population breeding true to the desired type?
due to the elimination of heterozygotes
negative effect of inbreeding
an increase in the frequency of individuals who are homozygous for recessive deleterious alleles
what will happen to individuals who are homozygous for recessive deleterious alleles, and what will this result in?
they will do less well at surviving to reproduce, which will result in inbreeding depression
in animals, what may happen when individuals from different breeds reproduce with eachother, and what can be done to continue to produce more of the result?
- a new crossbred population will be produced, with potentially improved characteristics
- the parent breeds can be maintained in order to produce more crossbred animals with the improved chracteristic
how are new alleles introduced to animal and plant lines?
by crossing a cultivar or breed with an individual with a different, desired genotype
in plants, how are F1 hybrids produced?
by crossing two different inbred lines
what is the result of crossing two different inbred plant lines?
F1 hybrids of a relatively uniform, heterozygous crop
F1 hybrids often have increased what? (2)
vigour and yield
why are F1 hybrids not usually bred together?
the F2 generation produced shows too much variation
what does genome sequencing allow?
organisms with desirable genes can be identified and then used in breeding programmes
how are GM plants created, and what is the difference between GM plants and natural plants?
- single genes for desirable characteristics are inserted into the genomes of crop plants
- GM plants have improved characteristics
what kind of plants can be used in breeding programmes?
plants which have been genetically modified by recombinant DNA technology
what genes may be inserted into plants used for plant breeding? (2)
- Bt toxin gene
- Glyphosphate resistance gene
what is the Bt toxin gene for?
pest resistance
what is the glyphosphate resistance gene for?
herbicide tolerance
