AP Biology 1.1 Essential Life Process Information
AP Biology: Essential Life Process Information Drill 1, Problem 1. If one parent is heterozygous for the sickle cell trait while the other parent does not carry it, what is the likelihood that their child will be a carrier?
| AP | AP Biology |
| AP Biology | Essential Life Process Information |
| Change in Genetic Makeup | Phenotypic variation and fitness |
| Genetics | Genetic Combinations Genomes Transcription and Translation |
| Language | English Language |
| Test Prep | AP Biology |
Transcript
All right, this is a pretty straightforward question... if we know what heterozygous means.
If we don't... we can always eeny-meeny-miney-moe the answer...
Let's assign S to represent a normal phenotype and s to represent a sickle cell phenotype:
In genetics, heterozygous means you have one of the dominant S, and also an abnormal, recessive
lowercase s.
This means that one parent has the genotype of big S, big S, and one has the genotype
big S, small S.
If we write out a Punnett Square to represent the possible genetic combinations for the child...
...we'll see that there is a 50% chance of the child being a carrier.
So...our answer's C!
Don't worry -- just because both your parents have a big S doesn't mean that you're going to have a... big S.
No Punnett Square intended.