Plant and Animal Breeding Flashcards
What is a plant field trail and what does it do?
A plant field trial is the type of investigation set up to:
Compare the performance of two different plant cultivations under the same set of experimental conditions
Find out the effect of different environmental conditions on a new cultivator of crop plant
Evaluate genetically modified crops
What makes a plant field trial unbiased?
Random – to decrease bias
Repetition – to increase reliability
Change only one variable - makes it fair
What are desirable characteristics in plants?
Increasing yield
Increasing nutritional value
Resistance to pests and diseases
Ability to thrive in a particular environment
What is selective breeding?
Selective breeding is when selected individuals are bred together to produce offspring with desired characteristics
What is the test cross?
A test cross is a cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait
What is outbreeding?
Outbreeding involves the fusion of two gametes from unrelated members of the same species e.g. cross pollinators
Outbreeding often prevents the expression of deleterious (harmful) traits because the recessive allele controlling the trait is masked by the dominant allele
What is inbreeding?
Inbreeding involves the fusion of two gametes from close relatives e.g. self pollinators
What are the problems with inbreeding?
Lots of heterozygosity – organisms become homozygous for the desired trait
Inbreeding depression – the accumulation of other homozygous traits which can cause the expression of harmful recessive alleles, this generally decreases the fitness, yield and fertility of the population
How to avoid inbreeding depression
Natural self pollinators are naturally inbreeding so they have a voided the effects of inbreeding depression because natural selection has worked over millions of years to weed out harmful alleles
In naturally outbreeding species, inbreeding depression is avoided by selecting a parental population with the desired characteristic but are otherwise genetically diverse
What is crossbreeding?
Crossbreeding is when animals/plants from different breeds/cultivars are bred with each other
The offspring produced are called the F1 generation
Back crossing must then be performed to eliminate unwanted genetic material but maintain the desired characteristic
What is backcrossing?
Crossing an F1 hybrid with a homozygous organism showing the desired characteristic (usually the parent)
What happens to the F1 generation if two cultivars (plant breeds ) are crossbred?
The F1 generation generally display a uniform heterozygous crop
The F1 generation often have increased vigour and yield and are more fertile because the recessive alleles are masked
What happens to the F2 generation if two cultivars (plant breeds ) are crossbred?
The F2 generation is generally genetically diverse and of little use although they can provide a source for new varieties
Usually no F2 generation is produced and the process of selection and backcrossing is required to maintain the new breed
Describe genetic technology
As a result of genome sequencing, organisms with desirable genes can be identified and then used in breeding programs
What is genetic transformation?
This technique allows a single gene to be inserted into a genome and then this genome can be used for breeding programs
