Key Area 2 Flashcards
What is selective breeding?
The process by which selected individuals are bred together to produce offspring with desirable features.
What are some desirable features in crop and livestock breeding?
- Higher yield
- Higher nutritional values (e.g. protein)
- Disease resistance
- Pest resistance
- Frost resistance
- High milk yield
- High meat yield
- Useful physical characteristic
- Ability to thrive in certain environment
Give an example of a crop that has been selectively bred for disease resistance.
Potatoes (to blight)
What is a plant field trial?
A type of investigation set up to compare the performance of different plant cultivars under the same experimental conditions.
What is the purpose of designing a plant field trial?
To compare different plant cultivars and find out the effect of different environmental conditions on a new cultivar.
What factors must be considered when designing a plant field trial?
- Selection of treatments
- Number of replicates
- Randomisation of treatments
What is the minimum number of replicates recommended to minimise experimental error?
A minimum of three replicates.
True or False: In a plant field trial, all variables except one should remain constant.
True
What is the benefit of randomising treatments in a field trial?
It helps eliminate bias when measuring treatment effects.
Fill in the blank: The process of bringing together desired alleles in breeding is aimed at producing offspring that are more ______ than the parents.
useful
What is a potential issue with non-randomised field trials?
Bias may exist due to environmental variability, such as wetter sides of the field.
Provide an example of a plant cultivar that may be tested in a field trial involving nitrogenous fertiliser.
A new cultivar of cereal plant.
What does the term ‘experimental error’ refer to in the context of plant field trials?
Differences in each plot and in how the experiment was carried out.
What is inbreeding?
Inbreeding involves the fusion of two gametes from close relatives and promotes homozygosity.
In which species is inbreeding naturally occurring?
In some species of self-pollinating plants like peas, wheat, and rice.
What is the desired effect of inbreeding?
Selected related plants or animals are bred for several generations until the population breeds true to the desired type.
What is inbreeding depression?
Inbreeding depression is an increase in the frequency of individuals who are homozygous for recessive deleterious alleles.
What negative effects can result from inbreeding?
- Loss of heterozygosity
- Inbreeding depression
What is crossbreeding?
Crossbreeding is the introduction of new alleles into a plant or animal species by crossing a cultivar or breed with an individual of a different genotype.
What is an F1 hybrid?
An F1 hybrid is an individual resulting from a cross between two genetically dissimilar parents.
What is the purpose of creating F1 hybrids?
To produce hybrids that have both desirable characteristics from the parent varieties.
What is the result of a cross between two different homozygous parents?
It creates a uniform F1 generation.
Why must F1 hybrids in animals be produced from true-breeding parents?
To maintain specific desirable traits in the crossbred animals.
What is the outcome of an F1 self-cross?
It produces a genetically diverse F2 generation.
