inheritance 2

Question 1

1. What process in meiosis gives all combinations of alleles in unlinked chromosomes?

Answer 1

Independent assortment of homologous chromosomes, this is the homologous pairs lining up on the equator in a random order and the chromosomes being pulled to either side of the cell.

Question 2

2. What process in meiosis can unlink, linked genes increasing the ratio of genotypes in the offspring.

Answer 2

Crossing over.

Question 3

3. In genetic crosses, the observed phenotypic ratios obtained in the offspring are often not the same as the expected ratios. Give reasons why.

Answer 3

Small sample size; Fusion of gametes is random; Lethal genotypes; (Linked Genes; Epistasis;)
(depending on the context of the question)

Question 4

4. What statistical test can be used for inheritance?

Answer 4

Chi Squared-test for the significant in differences between observed and expected categoric data.

Question 5

5. What would a null hypothesis be?

Answer 5

There is no significant difference between the observed and expected results.

Question 6

6.Some genetic diseases are late onset so patients do not know they have them until later life. Why does natural selection not reduce the allele frequency of the allele that causes these genetic diseases?

Answer 6

If the disease is late onset the patient may have already reproduced before symptoms become apparent.

Question 7

7. Why is there variation in the exact age of onset of a late onset genetic disease?

Answer 7

Epigenetics alters genes expression. Changes in the epigenome can be caused by environment/stress/alcohol/toxins/diet/exercise/smoking

Epigenetics involves methylation (of genes) OR acetylation (of histones).