Introduction

A good understanding of Mendelian inheritance is invaluable when studying evolution. As a result, we have provided a set of genetics problems approximately as difficult as those encountered in a high school biology class. Please solve the following problems, then click on "Show Solutions" at the bottom of this page. Good luck!

Problem #1

The ability to roll the tongue is dominant over the inability to do so in humans.

1. If two heterozygous tongue-rollers have children, what genotypes could their children have?
   
2. If a non-tongue-roller has children with a homozygous tongue-roller, what will their children's genotypes be?
   

Problem #2

In an alien species, eye colors can be black, white, or gray. A white-eyed mother and a black-eyed father have all gray-eyed children.

1. What genetic pattern is most likely demonstrated here?
   
2. A gray-eyed couple has two babies: one white-eyed and one black-eyed. Does this confirm or deny your answer to part A? If necessary, revise your hypothesis.
   
3. A gray-eyed alien and her black-eyed husband want a white-eyed baby. Is this possible?
   

Problem #3

A mother has blood type A and genotype AO. A father has blood type B and genotype BO. What blood types are possible for the offspring?

Problem #4

Pattern baldness is sex-linked, but cannot be expressed normally in females.

1. If a carrier female marries a pattern-bald man, what are the possible genotypes of their children?
   
2. If female is homozygous for pattern baldness (but does not express the trait due to hormones), and she marries a normal man, what percentage of her sons will be pattern-bald?
   

Problem #5

In pea plants, tallness is dominant over shortness and smooth seeds are dominant over wrinkled seeds. If two heterozygous tall plants which are heterozygous for smooth seeds are crossed, what are the genotypes and phenotypes of the offspring?

Biological Evolution | Cultural Evolution | Languages Philosophy | History of Evolution | Interactivities FAQ | Forum | Guestbook | References | About Us Home | Search | Index | Features | Newsflash! Site News | Our Awards | New!  Featured Links