Unit 2: Solving Punnett Squares

Unit 2: Solving Punnett Squares

See More
Try a College Course Free

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to over 2,000 colleges and universities.*

Begin Free Trial
No credit card required

28 Sophia partners guarantee credit transfer.

264 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 22 of Sophia’s online courses. More than 2,000 colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


Objectives and Instructions

Lesson Objective:

Using the Punnett square constructed in objective 1, the learner will be able to cross parental alleles, articulate the genotype and phenotype of each offspring an then analyze the likelihood that the parents would have a child with a widow’s peak.


Please watch the video tutorial to learn about the basics of Punnett squares. Using that information complete the practice problems below the video and score yourself using the key provided to check your understanding of the concepts. When you feel confident in your understanding of the concepts, complete the 5 quiz questions in the upper right corner of this page. 



Do you have a widow's peak or a straight hairline? In the last unit you determined what the genotypes associated with the hairline trait were. Now, what if you could somehow determine the probability of passing that trait to your future offspring? That is where Punnett squares come in handy! A Punnett square allows you to determine the probablility of offspring inheriting a particular trait as long as the parental genotypes are known. To solve a Punnett Square  you simply cross the parental alleles on the top of the box with the alleles on the side of the box to get the various combinations of alleles possible. From there you can analyze the potential combinations and determine the probability of a particular trait being inherited by offspring. See the video instruction below for more details. 


Video Instruction

Practice Problems

Full Screen