Success Homeschool

Year 12 Science · Patterns of inheritance

Name: ______________________

Date: ____________

1. Which genotype is heterozygous?
- ☐ (a) AA
- ☐ (b) Aa
- ☐ (c) aa
- ☐ (d) A
2. A pea plant with genotype pp has white flowers. 'White flowers' is its…
- ☐ (a) Genotype
- ☐ (b) Allele
- ☐ (c) Phenotype
- ☐ (d) Gamete
3. What is the expected phenotype ratio from Aa × Aa when A is completely dominant?
- ☐ (a) 1 : 1
- ☐ (b) 1 : 2 : 1
- ☐ (c) All dominant
- ☐ (d) 3 : 1
4. What is the expected outcome of AA × aa?
- ☐ (a) All Aa
- ☐ (b) Half AA, half aa
- ☐ (c) All aa
- ☐ (d) 1 AA : 2 Aa : 1 aa
5. Two carrier parents already have one child with cystic fibrosis. What is the chance their next child has it?
- ☐ (a) 0%
- ☐ (b) 25%
- ☐ (c) 50%
- ☐ (d) 100%
6. In a cross Aa × aa, what percentage of offspring are expected to be aa? (number)
7. Different versions of the same gene are called what?
8. In a cross Pp × Pp, what fraction of offspring are expected to be homozygous recessive? (fraction)

Answer sheet

1. Aa — Heterozygous means two different alleles.
2. Phenotype — The observable trait is the phenotype.
3. 3 : 1 — AA, Aa and Aa show the dominant phenotype; aa shows the recessive one.
4. All Aa — Every gamete from the first parent is A and from the second is a.
5. 25% — Each child is an independent event, so the probability is still 1 in 4.
6. 50 — Punnett square: Aa, Aa, aa, aa, so 2 of 4 = 50%.
7. alleles — Versions of a gene are alleles.
8. 1/4 — One of the four boxes is pp.