Question

Click an item in the list or group of pictures at the bottom of the problem and, holding the button down, drag it into the correct position in the answer box. Release your mouse button when the item is place. If you change your mind, drag the item to the trashcan. Click the trashcan to clear all your answers.

(purple smooth (PR)= 75, white smooth (pR)= 28, purple wrinkled (Pr)= 24, white wrinkled (pr)= 8)

Using symbols, diagram a cross that would give these results by completing the punnet square by placing the correct answers in their appropriate spot.

Answer 1

Both ppRr (white smooth) and Pprr (purple smooth) as the genotype for the second parent could result in the observed offspring ratios.

How to create Punnett square?

Identify the alleles:

Purple: P (dominant)

White: p (recessive)

Smooth: R (dominant)

Wrinkled: r (recessive)

Determine the genotypes of the parents:

Purple smooth (PR): Since it expresses both dominant traits, its genotype must be PpRr.

White smooth (pR): Since it expresses only one dominant trait (smooth), its genotype can be either ppRr or Pprr.

Set up the Punnett square:

| | PpRr (purple smooth) | Pprr (purple smooth) |

| PpRr (white smooth) | PpRR (purple smooth) | PpRr (purple smooth) | Ppwr (purple wrinkled) |

| pprr (white smooth) | ppRR (white smooth) | ppRr (white smooth) | ppwr (white wrinkled) |

Fill in the missing genotypes:

Since the parent genotypes aren't definitively determined, two possibilities exist for the second parent's genotype:

ppRr (white smooth): This leads to the following offspring probabilities:

PpRR: 1/4 (purple smooth)

PpRr: 1/2 (purple smooth)

pprr: 1/4 (white smooth)

ppwr: 1/4 (white wrinkled)

Pprr (purple smooth): This leads to the same offspring probabilities as the previous scenario.

Compare the offspring ratios to the given results:

Both possibilities for the second parent's genotype lead to the same offspring probabilities:

Purple smooth (PpRR, PpRr): 3/4 (75% match)

White smooth (ppRr, pprr): 1/4 (25% match)

Purple wrinkled (Ppwr): 1/4 (24% match)

White wrinkled (ppwr): 0 (8% mismatch)

Therefore, based on the information, both ppRr (white smooth) and Pprr (purple smooth) as the genotype for the second parent could result in the observed offspring ratios.