inheritance ,variation snd evolution Flashcards
what is variation?
Differences in the characteristics of individuals in a population is called variation
what are the two causes of variation within species?
Genetics
Environment
A mixture of both of the above
what is genetic variation?
Variations in the genotypes of organisms of the same species due to the presence of different alleles
Create differences in phenotypes
What creates genetic variation in a species?
spontaneous mutations
sexual reproduction
what is a mutation?
A random change the base sequence in DNA which results in genetic variance
they occur continuously
State the three types of gene mutation
Insertion
deletion
substitution
how may a gene mutation affect an organism phenotype?
Neutral mutation does not change the sequence of amino acids. Protein structure and function same. No effect on phenotype.
Mutations may cause a minor change in an organism phenotype, e.g. change in eye colour
Mutations may completely change the sequence of amino acid. This may result in a non-functional protein. Severe changes to phenotype.
what is the consequence of a new phenotype caused by a mutation being suited to an environmental change?
There will be a rapid change in the species
What is evolution?
A gradual change in the inherited traits within a population overtime
Occur occurs due to natural selection which may result in the formation of new species
outline the theory of natural selection
- Genetic variation is this due to spontaneous mutations.
- Selection pressures e.g. competition disease exist
- Random mutation gives an organism as selective advantage.
- Organism is better adapted to the environment and survives.
- Organisms reproduce, passing on its beneficial alleles
- Frequency advantageous alleles increase.
how do two populations become different species?
When their phenotypes become different to the extent that they can no longer interbreed to produce fertile offspring
What is selective breeding?
The process by which humans artificially select organisms with a desirable characteristics and breed them to produce offspring with similar phenotypes
outline the main steps involved in selective breeding
- Identify a desired characteristics.
- Select parent organisms that show the desire traits and breed them together.
- Select offspring with the desire trait and breed them together.
- Process repeated until all offspring have the desired traits.
give examples of characteristics selected for selective breeding
disease resistance in crops
Higher milk or meat production in animals
Gentle nature im domestic dogs
Large flowers
What is the main advantage of selective breeding?
crops produce a higher yield of grain
Cows produce a greater supply of milk
Plants produce larger fruit
Domesticated animals
other than in agriculture where else is selective breeding useful
In medical research
In sports, e.g. horse racing
outline the disadvantages of selective breeding
reduction in the gene pool
Inbreeding results in genetic disorders
Development of other physical problems, e.g. Respiratory problems in Bulldogs.
Potential to unknowningly select harmful recessive alleles
What is genetic engineering?
The modification of the genome of an organism by the insertion of a desired gene from another organism – genes from chromosomes of humans and other organisms can be cut out and transfer to cells of other organisms
Enable the formation of an organism with beneficial characteristics
Give an example of uses for genetically modified plants
disease resistance
Produce larger fruit
What is used for genetically modified bacteria cells?
To produce human insulin to treat diabetes mellitus
describe the benefits of genetic engineering
Increase crop yeilds for growing population
Useful in medicine
GM crops produce scarce resources
Describe the risk of genetic engineering
long-term effects on consumption of GM crops unknown
Negative environmental impacts e.g. reduction in biodiversity, impact on food chain, contamination of non-GM crops forming super weeds
late onset health problems in GM animals
GMC’s are expensive. LEDCs may be unable to find them or may become dependent on businesses that sell them.
what is the name for crops that have had their genes modified?
genetically modified crops, e.g. those modified to be resistant to insect attack and herbicides
what is Bacillus thuringiensis
insect larvae are harmful to crops
BT is a bacterium which secrets attacking that kills insect larvae