Final answer:
Individuals with sickle cell trait are heterozygous (Ss) and have a mix of normal and sickle-shaped red blood cells. This condition provides some resistance to malaria without the severe effects of sickle cell anemia found in homozygous recessive (ss) individuals.
Step-by-step explanation:
The genotypes related to sickle cell trait involve the combination of alleles for hemoglobin. In sickle cell anemia, a person who is homozygous recessive (ss) has all red blood cells containing the defective hemoglobin that causes them to sickle. In contrast, a person who is homozygous dominant (SS) will have normal red blood cells. However, an individual who is heterozygous (Ss) for the sickle cell trait has both normal and sickle-shaped cells. This heterozygous condition yields a phenotype where both the dominant and recessive alleles are expressed. As a protective measure against malaria, heterozygous individuals have natural resistance due to the sickle cell trait, although they do not typically suffer from the severities associated with sickle cell anemia as seen in homozygous recessive individuals.