Elise is a freshman college student taking Introduction to Biology. In lab, she is asked her parents' blood types to complete a Punnett square. She knows that she has type A blood and that her mother has type B, but she does not know her father's blood type. Elise's lab partner assures her that she can figure out her father's blood type just by knowing her own and her mother's. Is her lab partner correct? Explain why or why not.

Video transcript

Hi, everyone. Let's take a look at this practice problem together. Sarah is a high school student conducting a genetics experiment in her biology class. She is trying to determine the blood types of her siblings by creating a punit square. If her mother and father have a B blood types, what are the expected blood types of her siblings? The answer options are a blood types B and A B. Option B, blood types A O and A B, option C, blood types A B and A B and option D blood types bo and A B. So recall that blood type inheritance occurs where one aly or gene copy is inherited from each parent. For the blood types. There are three different types of alleles and those alleles are A B and O. Now, the question tells us that both of her parents have the blood type A B and we can also refer that refer to that as the genotype. So the parent's genotype is A B. So they have one AOL and one bal. That means that we can already eliminate both options B and D because Sarah's siblings will not ever inherit the O blood type from their parents. Now is the time that we move on to use the Punt square. Remember to solve the punnet square, you need the genotypes of the parents. So on the screen, I am putting up the completed punnett square. Now on the top of the punnet square, there are two different columns, one for each A lil of parent, one. So one for A L and one for bal on the side, there are two rows, one for each A L of parent 21 for A LL and one for be A L. So using this, we can fill in the possible genotypes of the offspring. And we do that by dragging down the corresponding a little from parent one with the corresponding a little from parent two. What does that mean? Let me show you an example. So for example, solving for this top left square, we drag down the A LL from parent one and we drag over the A L from parent two which gives us genotype A A. So if I've already filled in the pundit square and the possible genotypes or blood types are the following. So we have type A, type A B and type B. Therefore, the correct answer is going to be option C blood types A B and A B. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.