B14 Variation and Evolution Flashcards
what is variation?
the differences of the characteristics of individuals in a population
what are the three main causes of variation in a population?
- alleles that an individual has inherited (genetic causes)
- environment
- a combination of genes and evironment
what is genetic variation due to?
mutations of the DNA
what can happen rarely with a mutation?
it can lead to a completely new phenotype
what can a beneficial mutation and a change in phenotype lead to?
it can lead to a rapid change in the species
what is natural selection?
an organism which has a characteristic which makes it better adapted to the environment is more likely to survive and reproduce. the offspring may also have the alleles for the advantageous characteristics so are more likely to survive and spread the characteristic through the population.
what is evolution?
the change in the inherited characteristics of a population over time through a process of natural selection
how can two populations become two completely separate species?
they become so different in phenotype that they are no longer able to interbreed and produce fertile offspring
what are some examples of selective breeding?
- domestic dogs - bred to have a gentle nature
- food crops - disease resistant
- animals - produce more meat/milk
- plants - produce larger flowers
how do you carry out selective breeding?
- select the characteristics you want from a mixed population
- breed the parents with the selected characteristics together
- select the desired characteristics from the offspring and breed them together
- continue to do this so all the population have the desired characteristic
how do you get inbreeding?
when closely related plants or animals are bred together
what can inbreeding cause?
some breeds to be prone to disease or inherited defects
what happens during genetic engineering?
genes from one organism are cut out and transferred to a different organism.
this means the genome of the second organism is modified
what is a good example of genetic engineering?
bacteria which have been genetically modified to contain the human insulin gene and produce human insulin
what are GM crops?
crops which have been genetically modified to have enhanced characteristics such as greater yields
What characteristics can crops be genetically modified to have?
greater yields
disease or pest attack resistance
bigger or better fruits
herbicide resistance
what are some concerns for GM crops?
if they are harmful for wild flowers and insects
some people feel that more research should be done on the health effects of eating gm crops
what is gene therapy?
using genetic modification to treat inherited diseases
what are the steps of genetic engineering?
- identify the gene you want to transfer
- use enzymes to isolate the gene
- transfer the gene into a plasmid from bacteria
- the desired gene is transferred into the target organism
what is a vector?
a plasmid or virus which transfers DNA from one organism to another
when is a gene transferred in the life cycle of an organism?
at an early stage of the organism’s development to ensure all of the cells receive the transferred gene.
what is a clone?
a genetically identical organism to the parent organism
what is the advantage of cloning plants?
we know exactly what the clone’s characteristic will be as the clone is genetically identical to the parent
what do you do when you take cuttings from a plant?
you remove a small piece of the plant and dip the end into rooting powder that contains hormones to promote roots to grow
