1. A homozygous purple flower (PP) is crossed with a homozygous white flower (pp).
- P × p → All offspring will be Pp (heterozygous purple).
- Probability of purple offspring: 100% (all are Pp, which is purple).
- Probability of white offspring: 0%.
2. When a Pp plant is crossed with a Pp plant, the Punnett square is:
| | P | p |
|-------|-------|-------|
|
P | PP | Pp |
|
p | Pp | pp |
- Genotypic ratio: 1 PP : 2 Pp : 1 pp
- Phenotypic ratio: 3 purple : 1 white
- Probability of purple offspring: 75%
- Probability of white offspring: 25%
3. A homozygous pink snapdragon (RR) is crossed with a homozygous white snapdragon (rr).
- RR × rr → All offspring are Rr (pink).
- Probability of pink offspring: 100%
- Probability of white offspring: 0%
4. When a heterozygous pink snapdragon (Rr) is crossed with a homozygous white snapdragon (rr), the Punnett square is:
| | R | r |
|-------|-------|-------|
|
r | Rr | rr |
|
r | Rr | rr |
- Genotypic ratio: 2 Rr : 2 rr → 1:1
- Phenotypic ratio: 2 pink : 2 white → 1:1
- Probability of pink offspring: 50%
- Probability of white offspring: 50%
5. The sequence of the protein is:
- Start → Met → Val → Leu → Phe → Asn → Arg → Stop
- The codons for this sequence are:
- Met: AUG
- Val: GUU, GUC, GUA, GUG
- Leu: UUA, UUG, CUU, CUC, CUA, CUG
- Phe: UUU, UUC
- Asn: AAU, AAC
- Arg: CGU, CGC, CGA, CGG, AGA, AGG
- One possible mRNA sequence:
- AUG GUU CUU UUU AAU CGU UAG
- The corresponding DNA template strand (complementary to mRNA, with T instead of U):
- TAC CAA GAA AAA TTA GCA ATC
- The coding strand (same as mRNA, with T instead of U):
- ATG CAA GAA AAA TTA GCA ATC
6. The sequence of the protein is:
- Start → Met → Val → Leu → Phe → Asn → Arg → Stop
- The mRNA sequence: AUG GUU CUU UUU AAU CGU UAG
- The DNA template strand: TAC CAA GAA AAA TTA GCA ATC
- The DNA coding strand: ATG CAA GAA AAA TTA GCA ATC
Parent Tip: Review the logic above to help your child master the concept of genetics worksheet.
