Question

Which of the following are true of modifying and epistatic genes in regard to genetic diseases?  (1)

1. Modifying genes can account for the severity of a genetic disease
2. Modifying genes do not completely mask genes for a genetic disease.
3. Epistatic genes may cause a disease by masking normal genes.
4. The expression of modifying genes can be affected by environmental factors.

Select the true statements about sex influenced and sex limited traits: (circle all that apply) (2)

1. Sex-influenced traits and sex-limited traits are autosomal.
2. Sex-limited traits are coded for by genes only found in one sex.
3. Sex-influenced traits in an individual are inherited from both parents.
4. Sex-influenced traits will express differently in the different sexes.

Select the true statements about heritability in terms of passing on traits from parent to offspring.  Circle all that apply (1)

a) Heritability depends on the degree to which a trait is determined by genes and environmental factors.

b)  Qualitative traits tend to be of high heritability

c) Traits of low heritability include most genetic diseases.

d)  Intermediate heritability means that genes play little role in whether a trait is passed on or not.

Indicate whether each of the following fits expressivity (E), penetrance (P) or BOTH.  (1)

a) May be influenced by environmental factors. _______     

b) If incomplete, may be due to epistatic genes. ______                                   

c) Means the degree to which a given genotype shows the expected phenotype. _________

d) Other gene pairs affect the expression of a specific gene pair, but do not mask it. _________

Answer 1

a and c are true.

Modifying genes can account for the severity of a genetic disease
Epistatic genes may cause a disease by masking normal genes.

b and c are true.Sex-limited traits are coded for by genes only found in one sex.
Sex-influenced traits in an individual are inherited from both parents

a and d are true.

Heritability depends on the degree to which a trait is determined by genes and environmental factors.

Intermediate heritability means that genes play little role in whether a trait is passed on or not.

a and c are true.