genetics questions

Question 1

Q2.
(a) Mutation is one cause of genetic variation in organisms.
Give two other causes of genetic variation.?

Answer 1

= crossing over and independant segregration

Question 2

(b) Give one piece of evidence from the diagram above to show that the allele
for grey body colour is dominant.

Answer 2

= for these types of questions find 2 affected or unaffected with an opposite child, this means they both must be carriers to pass on a recessive allele

Question 3

(c) Explain one piece of evidence from the diagram above to show that the
gene for body colour is not on the X chromosome.

Answer 3

= to check for sex linkage look at fathers and opposite daughyers, possile with recessive genotype

Question 4

(a) In genetic crosses, the observed phenotypic ratios obtained in the offspring
are often not the same as the expected ratios.
Suggest two reasons why

Answer 4

= random fertilisation
= sample size too small
= epistasis sometimes

Question 5

What is meant by the term phenotype?

Answer 5

= observerable charactertiscs, determined by the genotype

Question 6

In fruit flies, the genes for body colour and wing length are linked. Explain
what this means.

Answer 6

= gene is found on the same chromosome

Question 7

when would you use a chi sqaured test?

Answer 7

= catergorical data

Question 8

What is the expected ratio for dihybrid crosses?

Answer 8

9:3:3:1