Based on the pedigree chart provided, we can determine the genotype of each family member and their likelihood of passing on the sickle cell trait.
The half-shaded circle and half-shaded square represent carriers of the sickle cell trait (heterozygous individuals), while the completely shaded square represents an individual who has sickle cell anemia (homozygous recessive).
Since the father is completely shaded, he must be homozygous recessive (ss). The mother must be a carrier (Ss) because she is half-shaded.
When we consider the offspring, we can use a Punnett square to calculate the probability of each possible genotype.
| | S | s |
|---|---|---|
| S | SS | Ss |
| s | Ss | ss |
The offspring are:
- Unshaded square: SS (homozygous dominant)
- Half-shaded circle: Ss (heterozygous carrier)
- Half-shaded circle: Ss (heterozygous carrier)
- Completely shaded square: ss (homozygous recessive)
Therefore, 1 out of 4 offspring (25%) has sickle cell anemia (ss genotype), while the other 3 offspring are carriers of the sickle cell trait (Ss genotype).
So the answer is 25%. and