| what is plant and animal breeding done for | to improve characteristics to help support sustainable food production |
| what do breeders develop crop and animals with | higher food yields
higher nutritional values
pest and disease resistance
ability to thrive in particular environmental conditions |
| what is meant by a valid experiment | all variables except the independent variable are controlled so it can be concluded that the effect is due to the independent variable |
| what is meant by reliable results | measurements are repeated at each level of the independent variable to reduce the effect of atypical results |
| what must scientists do when analysing new plant varieties | make valid unbiased assessment of the effects of selective breeding on new plant varieties |
| how do scientists assess the effects of selective breeding on new plant varieties | field trials |
| where are plant field trials carried out | in a range of environments |
| why are plant field trials carried out in a range of different environments | to compare the performance of different cultivars or treatments
to evaluate GM crops |
| what must be taken into account when designing field trials | the selection of treatments
the number of replicates
the randomisation of treatments |
| what is the effect of the selection of treatments on field trials | ensures valid comparison |
| what is the effect of the number of replicates on field trials | takes into account variability within the sample |
| what is the effect of he randomisation of treatments in field trials | eliminates bias when measuring treatment effects |
| what is the aim of inbreeding | to produce offspring with the combined or superior characteristics to their parents |
| what is inbreeding | the fusion of gametes from close relatives |
| how long does inbreeding in selected plants or animals go on for | several generations until the population breeds true to the desired type due to the elimination of heterozygotes |
| what can inbreeding cause, apart from desirable characteristics | an increase in the frequency of individuals who are homozygous for recessive deleterious alleles which will do less well at surviving to reproduce |
| what does in increase in the number of individuals who are homozygous for recessive deleterious alleles result in | inbreeding depression |
| what may breeding individuals from different breeds produce in animals? | a new crossbreed population with improved characteristics |
| how can new alleles be introduced to plant and animal lines | by crossing a cultivar or breed with an individual with a different, desired genotype |
| what are the offspring of mating two different breeds in cross breeding | f1 hybrids |
| what is hybrid vigour | the name for increased performance above the average of the parents that you get when crossing two different breeds to produce an f1 hybrid |
| what can the two parent breds be maintained to do in crossbreeding | to produce more crossbred animals showing the improved characteristic |
| in plants, what do f1 hybrids (produced by the crossing of two different inbred lines) create | a relatively uniform heterozygous crop |
| what do f1 hybrids often have | increased vigour and yield |
| what might plants with increased vigour have | increased disease resistance or increased growth rate |
| why aren't f1 hybrids usually bred together in plants and animals | the f2 produced shows too much variation |
| what can organisms with desirable genes be used for as a result of genome sequencing | they can be identified and then used in breeding programmes |
| what can be done to single genes for desirable characteristics | they can be inserted into the genomes of crop plants, creating genetically modified plants with improved characteristic |
| 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 | insertion of Bt toxin gene into plants for pest resistance
glyphosate resistance gene inserted for herbicide tolerance |
