Year 13 - Inheritance

Question 1

What does the hardy-Weinberg principle predict?

Answer 1

The frequency of alleles of a particular gene will stay constant from one generation to the next providing there is no mutation, migration, selection, mating is random, and population is large.

Question 2

Under what conditions does the hardy-Weinberg principle apply?

Answer 2

No gene mutation.
Random mating.
No migration.
Very large population size.
No natural selection.

Question 3

The actual percentage/frequency of q (or p/qq/pp/2pq) was lower than expected in future generations. Why?

Answer 3

Individuals with insert allele/genotype here do not reproduce/die therefore do no pass on their allele to future generations.

Question 4

1. Evidence for allele being recessive?
2. Evidence for allele not being on X chromosome?
3. Evidence for allele being on the x chromosome?
4. Evidence for allele being dominant.
5. Evidence for X linked disease/trait being recessive.
6. Evidence for Y linked disease

Answer 4

1. Two heterozygous parents and homozygous recessive child.
2. Homozygous recessive daughter and dad with dominant allele on X
3. Look for homozygous recessive mother and dominant phenotype son
4. Two dom phenotypes/ heterozygous parents with a recessive phenotype child
5. Heterozygous mum with a son who recessive phenotype/affected
6. Only males will have it, Dad always passes to son

Question 5

What is epistasis?

Answer 5

One gene influences the expression of another gene.

Question 6

What does it mean that genes are linked?

Answer 6

The different genes are on the same chromosome and are expressed together. Likely to be inherited together.

Question 7

What is meant by a sex-linked gene?

Answer 7

Sex linkage; gene located on X or Y chromosome (one sex chromosome)

Question 8

Why may a genetic cross give different phenotypic rations to what is expected?

Answer 8

1. Small sample size​
2. Fusion of gametes is random​
3. Linked Genes/ crossing over/ sex linkage​
4. Epistasis​
5. Lethal genotypes