B14- Variation and evolution Flashcards
Variation
Differences that exist within a species and between different species
Genetic variation
Def?
Examples?
Characteristics inherited through parents’ genes
Eye colour, sex, blood type
Environmental variation
Def?
Examples?
Characteristics influenced by the environment
Scars, tattoos, piercings
3 examples of characteristics that are inherited, environmental and both?
Inherited- eye colour, sex, blood type
Environmental- tattoos, scars, accent
Both- height, hair colour, weight
How is variation caused by mutations?
Are mutations planned?
Mutations in gamete formation can affect the phenotype of offspring
-They are random, usually have little effect on an organism. Very rarely make the organism better suited to its environment
Theory of evolution
Who?
What?
How long ago?
Charles Darwin
All species of living things have evolved from simple life forms from 3 billions years ago
Natural selection process? (3 steps)
-Variation exists within a population, causing different phenotypes
-Organisms that happen to be better suited to the environment are more likely to survive and breed successfully
-Their alleles are passed on the future offspring
How to tell if a new species has been formed?
When the species can no longer breed to produce fertile offspring
Selective breeding
When humans breed plants and animals with desired characteristics over many years
4 Examples of using selective breeding
-Disease resistant food crops/ garden plants
-Animals that produce more meat or milk
-Domestic dogs
-Large, bright flowers
4 Limitations of selective breeding
-Inbreeding
-Less alleles in population
-Limits variation
-Less likely to survive a change in environment
Genetic engineering
Deliberate modification of an organism’s genetic material at early stage of development to obtain desired characteristic
How to use genetic engineering to produce insulin?
-Remove DNA from human producing insulin cell
-Enzymes cut out insulin producing gene
-Remove plasmid from bacterium, enzymes insert insulin producing genes into plasmid
-Plasmids reinserted to bacteria
-Insulin producing bacteria multiply
4 Uses of genetic engineering
-Manufacturing insulin
-Crops that produce a greater yield
-Crops resistant to disease
-Find out where genes are expressed
Clone
An individual that has been produced by asexual reproduction, is genetically identical to parent
4 methods of cloning
Plants- tissue culture, plant cuttings
Animals- embryo transplant, adult cell cloning
Tissue culture
Explanation?
Used for?
Small tissue sample, mixed with hormones and nutrients, creating mass of identical cells called callus
-Preserving rare species, quickly obtain desired characteristics, commercial buying
Plant cuttings
Explanation?
Ads?
Cut part of plant, dip in hormone rooting powder, plant in correct conditions
-Old, simple, cheap
Embryo cloning
Explanation?
-Fertilise egg cell from cow w sperm cell from bull to form zygote
-Forms a ball of cells which are then split apart
-Each cell forms a new ball of cells, placed into a surrogate mother cow
-Produces identical calves
Adult cell cloning
Explanation?
-Remove nucleus from unfertilised egg cell
-Take nucleus from adult body cell and put in the egg cell
-New egg cell given electric shock to stimulate cell division
-Grows into embryo, placed back in uterus
-Embryo has same genes as adult body cell
Adult cell cloning
Ads & dis
Ads- Can save animals from extinction, produce human baby clones for infertile couples, produce animals that provide useful substance
Dis- Concern over ethics, doesn’t work every time, reduces variation, less chance of survival
Genetic engineering
Ads & dis
Ads- Help food security due to high yield, high nutrition, could cure human diseases by replacing genes w healthy ones
Dis- Concerns to humans when eating GM crops, can affect food chains, limits genetic variation
