3.2 plant and animal breeding Flashcards
what do breeders develop crops and animals with
- higher nutritional values
- higher food yields
- pest and disease resistance
- ability to thrive in particular environmental conditions
What is a plant field trial
-a type of investigation set up in a range of environments that are used to compare the performance of different cultivars or treatments under the same experimental conditions
What factors must be considered while investigating
- selection of treatments
- number of replicates to be included
- randomisation of treatments
Plant field trial considerations - selection of treatments
-for each sample only one variable should be altered and all other variables need to be kept the same (so the comparison is fair)
Plant field trial considerations - number of replicates
- if only taking one sample for each of the different conditions then the results would be unreliable
- repeat/replicate minimises experimental error which takes into consideration the differences at each sample site (variability)
Plant field trial considerations - randomisation of treatments
-randomly allocating the sample sites for each sample instead of deciding where to sample (reduce bias)
What is inbreeding
-the fusion of 2 gametes from close relatives
What is a negative result of inbreeding
- an increase in recessive homozygosity
- homozygous alleles can be deleterious resulting in inbreeding depression
What is cross breeding
-when 2 individual animals from completely different breeds mate and produce offspring
What is a reason animals may be crossbred
-to produce possible improved characteristics
What is a hybrid
-when there has been crossing of 2 different inbred lines in plants
What do 2 inbred parents produce
-a F1 hybrid
What do F1 hybrids tend to produce
-heterozygous crops
What characteristics do F1 hybrid heterozygous crops often have
- increased vigour (strength/health)
- increased yield
- may be resistant to diseases and or have increased rate of growth
Why aren’t F1 hybrids usually bred togethrr
-the F2 generation offspring would have too much variation and lack the improved characteristics
