4.3.1 Classification and Evolution – Variation Flashcards
(12 cards)
What is variation?
Differences in/within/between species.
What is the difference between interspecific and intraspecific variation?
Interspecific variation is the differences between species whereas intraspecific variation is variation between members of the same species.
What is continuous variation?
Variation where there are two extremes and a full range of values in between.
What is discontinuous variation?
Where there are distinct categories and nothing in between.
What is environmental variation?
Variation caused by response to environmental factors such as light intensity (these cannot be inherited).
What is genetic variation?
Variation caused by possessing a different combination of alleles.
What two major factors can result in genetic variation?
Mutations in the genes or chromosomes, and sexual reproduction.
During sexual reproduction, name 3 ways in which allele combinations can be ‘shuffled’ to result in variation.
Any 3 of the following:
- Crossing over
- Independent assortment of chromosomes
- Independent assortment of chromatids
- Random fusion of gametes at fertilisation
- Random mating between individuals
List 4 examples of continuous variation.
Any sensible examples, e.g.
- Height in humans
- Length of leaves on an oak tree
- Length of fingers
- Number of flagella on bacterium
List 3 examples of discontinuous variation.
Any sensible answer, e.g.
- Gender
- Presence/absence of flagella
- Human blood groups
Why is discontinuous variation often caused by the action of just one gene?
One gene is needed to produce one polypeptide or protein so the presence of a different allele can produce the difference between two characteristics.
Why is it less easy to spot interspecific variation between species that are closely related?
Species are classified according to their similarities and differences. Closely related species will have fewer differences and those differences will be smaller than those between less closely related species.
