8.A gardener is cross-pollinating flowers and observes an interesting result. When a plant with red flowers (RR) is crossed with a plant with white flowers (WW), all of the offspring have pink flowers.

Question

Create a Punnett square to predict the flower colors of the offspring if two pink-flowered plants (RW) are crossed. What is the genotypic and phenotypic ratio?

What inheritance pattem best explains how flower color is passed down in these plants? Explain your reasoning

Answer 1

To analyze the inheritance pattern of flower color in the described plants, we first note the genotypes involved:

• Red flowers: RR
• White flowers: WW
• Pink flowers: RW (the result of the cross between RR and WW)

Step 1: Cross two pink-flowered plants (RW)

To predict the offspring of a cross between two RW (pink) plants, we can set up a Punnett square.

Punnett Square:

        R       W
      ----------------
    R |   RR   |   RW   |
      ----------------
    W |   RW   |   WW   |
      ----------------

Step 2: Analyze the results

From this Punnett square, we can tally the possible genotypes and phenotypes of the offspring:

• Genotypes:
  • RR (homozygous red): 1
  • RW (heterozygous pink): 2
  • WW (homozygous white): 1

This gives us:

• 1 RR
• 2 RW
• 1 WW

Step 3: Determine ratios

Genotypic Ratio:

• RR : RW : WW = 1 : 2 : 1

Phenotypic Ratio:

In terms of flower colors:

• Red : Pink : White = 1 : 2 : 1

Inheritance Pattern

The inheritance pattern that best explains how flower color is passed down in these plants is incomplete dominance.

Reasoning:

1. Red (RR) and White (WW) parent colors produce Pink (RW) offspring, indicating that neither allele completely masks the presence of the other.
2. The resulting phenotypes of the offspring show a mix of the two parental traits, leading to a third phenotype (pink) rather than a blend or one being dominant.
3. When two RW plants are crossed, the likelihood of producing offspring of all three phenotypes (red, pink, and white) supports the idea of incomplete dominance, as each flower color can be represented as a distinct phenotype.

In conclusion, the genotypic ratio of the offspring from the RR x WW cross is 1:2:1, and the phenotypic ratio is also 1:2:1. The mode of inheritance evident here is incomplete dominance, where the heterozygous expression (RW) results in a phenotype distinct from either homozygous parent.

Answer 2

Can you make the explanation shorter and make it seem like a 9th grader wrote it?

Answer 3

Sure! Here’s a simpler and shorter version:

Step 1: Cross two pink-flowered plants (RW)

When we cross two pink-flowered plants (RW), we can use a Punnett square to predict the offspring.

Punnett Square:

        R       W
      ----------------
    R |   RR   |   RW   |
      ----------------
    W |   RW   |   WW   |
      ----------------

Step 2: Results

From the Punnett square, the possible genotypes are:

• 1 RR (red)
• 2 RW (pink)
• 1 WW (white)

Step 3: Ratios

Genotypic Ratio:

• RR : RW : WW = 1 : 2 : 1

Phenotypic Ratio:

• Red : Pink : White = 1 : 2 : 1

Inheritance Pattern

This flower color pattern is called incomplete dominance. This means that when a red (RR) flower and a white (WW) flower are crossed, the offspring are pink (RW).

So in this case, the pink flowers show that neither red nor white fully dominates. Overall, the offspring of two pink flowers can be red, pink, or white, which fits with incomplete dominance!