17.4 dihybrid inheritance

Question 1

what is the law of independent assortment

Answer 1

alleles for different genes segregate independently during gamete formation in meiosis unless they are linked

Question 2

what is a dihybrid cross

Answer 2

shows the simultaneous inheritance of two genes controlling separate characteristics

Question 3

dihybrid crosses can help to

Answer 3

• determine whether genes are linked
• locate genes in specific chromosomes
• calculate expected phenotypic ratios in subsequent generations

Question 4

what is true/pure breeding organism

Answer 4

• homozygous for traits being studied

Question 5

what can a 9:3:3:1 show

Answer 5

both parents are heterogeneous at both gene loci

Question 6

what are the reasons for deviations form expected ratios

Answer 6

1. random fertilisation
2. small samples can lead to skewed rations
3. lined genes are on the same chromes do alleles are usually inherited together