Chapter 7

Question 1

1.What is a “Dihybrid cross”?

Answer 1

A method that is used to demonstrate a predictable pattern of the inheritance of two traits.

Question 2

List 2 human diseases that are “sex-linked”

Answer 2

Hemophilia and colorblindness

Question 3

What is a pedigree

Answer 3

A chart that shows all of the known phenotypes for an organism and its ancestors, most commonly including prevalent diseases in a family, traits in animals, etc.

Question 4

6. How many of the hypothetical “babies” produced in your class were identical?

Answer 4

Zero

Question 5

7. How many alleles control hair color in humans? How many for eye color? What do we call the kind of dominance these traits represent?

Answer 5

3 alleles control hair colore and 2 control eye color.

These traits are called polygenetic.

Question 6

8. What does the 9:3:3:1 ratio refer to?

Answer 6

The 9:3:3:1 is the result of a dihybrid cross between two heterozygous parents.This means that you’re mapping out a cross while observing two alleles. Instead of observing the genotypes, however, you are observing the phenotypes.

Question 7

9. What is the difference between a “gene” and an “allele?”

Answer 7

A gene is a specific section of a chromosome where the base pairs that code for the characteristic are stored whereas an allele is the actual sequence of the base pairs in the section.

Question 8

10. How many alleles are involved in a dihybrid cross? How many genes?

Answer 8

4 alleles and 2 genes

Question 9

11. Which of these is dominant: tongue-rolling, color-blindness, ability to taste PTC, widows’ peak?

Answer 9

tongue-rolling, widows’ peak, PTC tasting