5.6 Inheritance Conditions In Humans

Question 1

What type of genotype is polydactyly caused by?

Answer 1

Homozygous dominant or heterozygous (the dominant allele)

Question 2

If the allele for the genetic disorder is dominant, how many alleles do they need to inherit to get the disorder?

Answer 2

1

Question 3

If the allele for the genetic disorder is recessive, how many alleles do they need to inherit to get the disorder?

Answer 3

2

Question 4

What is cystic fibrosis?

Answer 4

Where the alleles affect the cell membrane and cause thick, sticky mucus to be produced which affect several organs including the lungs and the pancreas

Question 5

What genotype is CF caused by?

Answer 5

Homozygous recessive (recessive allele)

Question 6

How can CF be passed down between generations who don’t have CF?

Answer 6

The parents are carriers, which means their genotypes for CF are heterozygous, therefore the have the recessive alleles but they have the dominant alleles too so the recessive CF allele is masked by the dominant one, however if both parents pass down the recessive allele then the child will have CF

Question 7

If we know the parents genotype for a disorder how can we predict the child will have the disorder or not?

Answer 7

By using punnet squares we can predict the probability that the child will inherit each allele combination so will have the disorder or not

Question 8

What are the three combinations of alleles?

Answer 8

• AA (homozygous dominant)
• Aa (heterozygous)
• aa (homozygous recessive)

Question 9

What is polydactyly?

Answer 9

A genetic disorder where a baby is born with extra toes or fingers