Types of Variation Flashcards
Name 3 ways that variation can arise.
Mutations
Meiosis
Random Fertilisation of Gametes
Why do mutations lead to variation?
They lead to sudden changes to genes and chromosomes that could be passed onto the next generation.
This means production of new alleles.
Why does meiosis lead to variation?
Crossing over and genetic recombination occurs leading to new allele combinations in chromosomes.
Why does random fertilisation of gametes lead to variation?
The male gamete that fuses with the egg is completely randoms
What non biological factor can lead to variation?
The environment
Give examples of environmental factors that can lead to variation.
Temperature, diet, rainfall, pH
What is continuous variation?
Give an example.
A type of variation that cannot be put into categories. For example, height.
Name 2 types of graph that could show continuous variation.
What shape curve is likely to be produced?
Histogram or Line graph.
They are likely to display a bell shaped curve.
What is discontinuous variation?
Give an example.
A type of variation that fits into categories. You will either have the characteristic or you won’t.
Eg: Blue or brown eyes.
Name a type of graph that could represent discontinuous variation.
Bar graph.
Explain the impacts of mutations on alleles in organisms.
They could have a positive impact where mutations lead to new advantageous alleles.
They could have no impact.
They could be disadvantageous.
Briefly describe crossing over in meiosis.
Homologous chromosomes get very close to each other. This means that the non sister chromatids entangle and cross over. The point where they entangle places stress on DNA molecules causing a section of the chromatid to break and re-join elsewhere with a chromatid from the chromosome.
Briefly describe independent assortment.
Homologous pairs of chromosomes randomly align across the equator of the spindle in meiosis. This means that when the cell divides, they each receive a random set of each chromosome.
