5. Why is it difficult to diagnose genetic conditions?
6. Explain how Down syndrome, also called Trisomy 21, occurs.
7. Discuss why a silent mutation does not affect the function of a genetic sequence.

The diagram shows the results when two parents are crossed. the letters represent alleles for a trait that is controlled by three different genes. which best describes this inheritance pattern? multiple allele because a trait is controlled by three different genes polygenic because the offspring have alleles from both parents multiple allele because the offspring have alleles from both parents polygenic because a trait is controlled by three different genes