Genetic diversity and adaptations Flashcards
What is genetic diversity?
Number of different alleles of genes in a species or population
What is a factor which allows genetic diversity to occur
genetic diversity
what are the four basic steps of natural selection ?
1) Random mutation can result in new alleles of a gene
2) Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possesor, leading to reproductive success
3) The advantageous allele is inherited by members of the next generation
4) As a result, over many generations, the new allele increases in frequency in the population
what are the four basic steps of natural selection ?
1) Random mutation can result in new alleles of a gene
2) Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possesor, leading to reproductive success
3) The advantageous allele is inherited by members of the next generation
4) As a result, over many generations, the new allele increases in frequency in the population
What is directional selection/ when does it usually occur?
-Natural selection which produces a gradual change in allele frequencies over several generations
-Happens when there is a change in the environment/ selection pressures or a new allele has appeared in a population which is advantageous
How does antibiotic resistance exemplify directional selection ?
-The presence of antibiotics is a selection pressure
-Mutations are occurring in bacteria populations randomly
-A mutation arises that confers antibiotic resistance - it is a beneficial allele
-Bacteria with this mutation are more likely to survive and reproduce
-Most bacteria without the resistance mutation die
-Over generations, this leads to an increase in the frequency of beneficial allele that produces antibiotic resistance
What is stabilising selection/ when does it usually occur?
-Stabilising selection is natural selection that keeps allele frequencies relatively constant over generations
-This means things stay as they are unless there is a change in the environment
How does birth weight exemplify stabilising selection?
-Very-low and very-high birth weights are selected against leading to the maintenance of the intermediate birth weights (very big and very small babies die, so average sized baby phenotype is passed on)
What would stabilising and directional selection look like on a graph?
Bell curve on average for stabilisng, and either side of average for directional
What does natural selection result in?
species that are better adapted for their environment
In which three ways can an animal be adapted as a result of natural selection?
-Anatomical adaptations- structural features which increase an organism’s chance of survival/reproduction
-Physiological adaptations- Process inside an organisms body which increases its chance of survival/reproduction
-Behavioural adaptations- the way an organism acts which increases chance of survival/reproduction
What are two factors which contribute to the diversity of living organisms?
-adaptation, selection
What are examples of aseptic technique?
-Regularly disinfect work surfaces
-use sterile equipment
-convection current of bunson
-open lid towards bunson
-briefly flame neck of the container just before opened and closed
what is the section in the agar plate called where the bacteria cannot grow
zone of inhibition
what piece of equipment is used to place in paper discs soaked in antibiotic
forcep
