Mastering Genetics for the Kaplan Nursing Entrance Exam

If one parent is homozygous dominant and the other is homozygous recessive, which phenotype might appear in the F2 generation?

• A. Dominant phenotype
• B. Recessive phenotype
• C. Codominant phenotype
• D. Incompletely dominant phenotype

Answer: (A)

In a situation where one parent is homozygous dominant (having two dominant alleles) and the other is homozygous recessive (having two recessive alleles), the first generation of offspring (F1 generation) will all inherit one dominant allele from the dominant parent and one recessive allele from the recessive parent. This results in all F1 individuals expressing the dominant phenotype because the dominant allele masks the effect of the recessive allele. When these F1 offspring are crossed to produce the F2 generation, the genetic combinations will provide the opportunity for different phenotypes to arise. The F2 generation will exhibit a phenotypic ratio that stems from the segregation of the alleles during gamete formation in the F1 generation. Depending on the specific ratios obtained from the genetic cross, the potential for both dominant and recessive phenotypes exists. However, because one of the parents is homozygous dominant, the dominant phenotype is expected to occur more frequently. Thus, in the F2 generation, the presence of the dominant phenotype is guaranteed due to the homozygous dominant nature of one parent contributing that gene, which is why this answer is the most appropriate. Recessive phenotypes can also emerge but will be less common relative to

Genetics plays a pivotal role in understanding human biology, especially when preparing for a nursing career. One of the fundamental concepts you’ll encounter is the idea of dominant and recessive phenotypes. So, what do we really mean when we discuss these terms in the context of genetics?

Let's set the stage with a classic genetic scenario: consider a parent who is homozygous dominant and another who is homozygous recessive. This genetic cocktail immediately gives rise to a fun discussion about the offspring, often referred to as the F1 generation. Imagine this—each F1 offspring inherits one dominant allele from one parent and one recessive allele from the other. What do you think happens? You guessed it! All of them will exhibit the dominant phenotype because that pesky recessive allele can’t overshadow the dominant one.

Now here’s where it gets even more interesting! Those F1 offspring don’t just stop there; they can have their own little ones, leading us to the F2 generation. When the F1 generation is crossed, the genetic combinations explode into a world of possibility. You might think, “Wait, so what will pop up in the F2 generation?” The genetic pairings will allow both dominant and recessive phenotypes a chance to shine—though, let’s be real, the dominant phenotype is likely to take center stage.

Why is that? Well, the presence of a homozygous dominant parent guarantees that at least some offspring will showcase the dominant phenotype. That’s good news if you’re studying for the Kaplan Nursing Entrance Exam, as understanding these principles can make complex genetic ideas much clearer.

When we delve into genetics, we often talk about the expected phenotypic ratio derived from the segregation of alleles during gamete formation. Thinking about it the way you’d think of a recipe—there’s a certain measure of ingredients that leads to specific outcomes—helps clarify what’s going on in genetic crosses. The F2 generation’s outcomes depend largely on how these alleles mix and mingle.

So, what’s the takeaway here? While the chance for recessive phenotypes exists due to allele combinations, the dominant phenotype shines brightest in this scenario. As you prepare for your Kaplan Nursing Entrance Exam, remember that these genetic basics aren’t just for the classroom; they’ll apply in real-world nursing scenarios, too.

And in a world where nursing demands a profound understanding of human biology and genetics, your grasp of how dominant and recessive traits interact will be invaluable. As you sit there with your study materials spread around, reflect on how those simple allele combinations can lead to such an intricate tapestry of genetic traits.

Feeling overwhelmed? Don't be! Each concept builds on the last, and mastering these ideas—like the dominant phenotype in our scenario—will boost your confidence and understanding. So, keep digging into your resources, and remember, you’re not just passively preparing for an exam—you’re actively setting the stage for your future in nursing!