KA3.6 - Evolution Flashcards
A mutation is a … & … change in the structure or amount of an organism’s DNA.
sudden & random. A mutation is a sudden & random change in the structure or amount of an organism’s DNA.
What is the only source of new alleles?
Mutations
How might a mutation affect the DNA?
Change the number of chromsomes, order/number of genes or bases.
What can cause an increase in the rate of mutations?
Radiation and some chemicals
Are all mutations harmful?
No. They can be neutral (having no positive or negative affect), advantageous or disadvantageous.
What are the three types of mutation?
Neutral (having no positive or negative affect), advantageous or disadvantageous.
Variation in a population can be due to … creating new alleles, the combination of genes inherited from parents or … (diet, exercise etc.)
Variation in a population can be due to mutations creating new alleles, the combination of genes inherited from parents or environmental influences (diet, exercise etc.)
What type of variation is controlled by genes and the environment?
Continuous variation. As this has any value from a minimum to a maximum (e.g. height) it can impacted by the environment (e.g. if you got enough food when you were growing).
An adaptation is an … characteristic that makes an organism … in its environment.
inherited … well suited to surival. An adaptation as an inherited characteristic that makes an organism well suited to survival in its environment/niche.
When does natural selection occur?
When species produce more offspring than the environment can sustain which produces selection pressures as organisms compete for limited resources, e.g. food, light, water, mates
In the context of natural selection a selective advantage is when those … to the environment survive and …
best suited … reproduce. Those best suited to the environment survive and reproduce
What are the steps of natural selection?
1 - Species produce more offspring than the environment can sustain which produces selection pressures as organisms compete for limited resources.
2 - There is wide range of variation between individuals so those best suited to the environment survive and reproduce (selective advantage).
3 - ‘Successful’ characteristics are passed to offspring.
4 - Those that are less well adapted and compete less successfully will die out, leaving only the ‘fittest’ to survive and reproduce.
A species is a group of …
A species as being a group of organisms that are able to breed and produce fertile offspring.
What process produces new species?
Speciation.
A barrier must be present for speciation to occur, why?
Stops gene flow. For two groups to become different species they must not be allowed to reproduce with one another or they will not become sufficiently different to be considered different species.
