2. plant and animal breeding Flashcards
Breeders want to develop crops and animals with:
-higher food yields,
-higher nutritional values,
-pest and disease resistance
-ability to thrive in particular environmental conditions. (high temperatures, drought)
explain what is meant by Valid (experiment/trial)
All variables except the independent variable are controlled so it can be concluded that the effect is due to the independent variable.
explain what is meant by Reliable (results)
Measurements are repeated at each level of the independent variable to reduce the effect of atypical (abnormal) results. (eg. 1%, 1.5%, 10% - calculate average which is not as extreme as atypical result)
In designing field trials, account has to be taken of
-The selection of treatments to ensure valid comparisons,
-the number of replicates to take account of the variability within the sample
-the randomisation of treatments to eliminate bias when measuring treatment effects.
what is the purpose of inbreeding
produce offspring with the combined or superior characteristics to their parents
it involves the fusion of gametes from close relatives
When inbreeding is performed for long periods of time…
there is a decrease of heterozygosity.
This means plants or animals become homozygous for the trait being selected
what is inbreeding depression
inbreeding can also cause an increase in the frequency of individuals who are homozygous for recessive deleterious alleles.
These individuals will do less well at surviving to reproduce (eg. reduced food yield)
why is crossbreeding done
to produce a new crossbreed population with improved characteristics.
New alleles can be introduced to plant and animal lines by crossing a cultivar (produced by humans) or breed with an individual with a different, desired genotype (different cultivar/breed)
what is Hybrid vigour
the name for the increased performance above the average of the parents that you get when crossing two different breeds to produce an F1 hybrid
Why is crossbreeding parents together a better idea than breeding the F1 hybrids together
The F1 hybrids are heterozygous which means that 25% of their offspring will be homozygous recessive
In inbreeding animals and plants, why are F1 hybrids usually not bred together
the F2 produced shows too much variation.
what are the benefits of F1 hybrids in plants
F1 hybrids often have increased vigour and yield. Plants with increased vigour may have increased disease resistance or increased growth rate
describe genetic technology in breeding programmes
As a result of genome sequencing, organisms with desirable genes can be identified and then used in breeding programmes.
Single genes for desirable characteristics can be inserted into the genomes of crop plants, creating genetically modified plants with improved characteristics.
Breeding programmes can involve crop plants that have been genetically modified using recombinant DNA technology.
Which process could you use to identify a particular gene in 2 organisms identical apart from one allele?
genomic technology
examples of recombinant DNA technology in plant breeding
insertion of Bt toxin gene into plants for pest resistance
glyphosate resistance gene inserted for herbicide tolerance.
