Punnett square 2

You and a few classmates have just selected Punnett square 2, confirming that all F1 offspring in Mendel’s experiment should be heterozygous purple (Aa). You’re gathered around a lab bench with Dr. Foster, comparing notes and practicing drawing Punnett squares. 

You: ‘Yes, it seems we have all purple flowers in the F1 generation. But where’s the white color we saw originally?’

Dr. Foster: ‘Good observation. The white coloration appears in the F2 generation, not the F1. Let’s illustrate how that happens. Go ahead and open a new page on your tablet, and we’ll try to predict the next set of offspring using another Punnett square.’

Alice: ‘Right, so for the F2, we’ll cross two of these heterozygous purple flowers, both Aa. That way, we can see if the white trait shows back up.’

Dr. Foster: ‘Exactly. We’ll label each parent’s alleles across the top and left side. Then, we’ll fill in the four combinations they can produce. Let’s walk through it step by step to visualize which genotypes reintroduce the white phenotype.’

You grab your Tablet and stylus pen again and opened a blank page on the Tablet.

Pick the correct illustration of Punnett square!

Punnett square 3:

Punnett square 4: