Variation Flashcards
What is variation?
The differences between individuals of the same species
What is phenotypic variation?
Differences in physical characteristics, caused by both genetic and environmental factors
Genetic variation is…
The differences in genetic makeup
What is continuous variation?
A range of phenotypes between two extreme limits
What is discontinuous variation?
A limited number of phenotypes with no intermediates. It is mostly caused by genes alone
A change in the base sequence of DNA is known as …
A mutation
A genetic change is known as…
A gene mutation
What are examples of continuous variation?
Height, weight, hair length
What are examples of discontinuous variation?
Blood type, eye colour, tongue rolling
What happens if a chromosome pair fails to split during meosis?
One daughter cell may have two chromosomes from that pair instead of 1. If the egg cell is fertilised, it will lead to Down Syndrome.
What can mutations lead to?
Similar facial characteristics, heart problems, physical and physiological difficulties.
What factors increase the chances of a mutation occurring?
Ionising radiation, Chemicals
It damages bases in DNA. If this happens in the ovaries or testes, the altered DNA can be passed on to offspring. What is it?
Ionising raidation
They interfere with the process of DNA replication. This causes faulty DNA to be produced. An example is mercury.
Chemicals - mutagens
What are adaptive features?
The inherited funtional features of an organism that increase its fitness.
