18.2: Variation in Phenotype Flashcards
What do individuals in a population of a species often show
A wide range of variation in their phenotype
What is this variation in their phenotype due to
Genetic Factors
Environmental Factors
What is the primary source of variation
The primary source of variation is mutation
What are the 3 sources of variation
Mutation (Primary)
Meiosis
Random fertilisation of Gametes
Is variation ever due to one source of variation
No, it is often a combination
How do genetic differences occur in a population if every member has the same genes
Genetic differences occur due to members of the population having different alleles of the genes
Where/when do these differences occur
In living organisms
From generation to generation
Genetic differences as a result of mutations
Sudden changes to genes and chromosomes may be passed on to the next generation
Genetic differences as a result of meiosis
Meiosis is a special form of nuclear division, producing NEW combinations of alleles
These new combinations are produced before they are passed into the gametes, therefore they are different
Genetic differences as a result of random fertilisation of gametes
In sexually reproducing organisms, new combinations of alleles are produced and therefore their offspring are different
Which method does genetic differences occur by
A combination of all 3. A genetic difference as a result of just one is very rare.
What other factors influence the way genes are expressed
Environmental factors, they exert an influence on all organisms
