Answer :
To determine the genetic makeup of the red geranium parent, we can analyze the offspring from the cross with a white geranium.
1. Traits Description:
- Red flowers appear if the plant has either two dominant alleles (RR) or one dominant and one recessive allele (Rr).
- White flowers appear only if the plant has two recessive alleles (rr).
2. Cross Analysis:
- The white geranium used for the cross is homozygous recessive (rr).
3. Offspring Results:
- The offspring consists of half red-flowered plants and half white-flowered plants.
4. Genetic Interpretation:
- For the offspring to have both red and white flowers, the red parent must have contributed one dominant R allele to some offspring (resulting in red flowers) and one recessive r allele to the others (resulting in white flowers).
- This indicates that the red geranium parent must be heterozygous (Rr). Only with this genotype (Rr), when crossed with a white geranium (rr), can you get:
- 50% offspring with Rr genotype (red flowers)
- 50% offspring with rr genotype (white flowers)
Thus, the genetic makeup of the red geranium parent is heterozygous for red flowers, Rr.
1. Traits Description:
- Red flowers appear if the plant has either two dominant alleles (RR) or one dominant and one recessive allele (Rr).
- White flowers appear only if the plant has two recessive alleles (rr).
2. Cross Analysis:
- The white geranium used for the cross is homozygous recessive (rr).
3. Offspring Results:
- The offspring consists of half red-flowered plants and half white-flowered plants.
4. Genetic Interpretation:
- For the offspring to have both red and white flowers, the red parent must have contributed one dominant R allele to some offspring (resulting in red flowers) and one recessive r allele to the others (resulting in white flowers).
- This indicates that the red geranium parent must be heterozygous (Rr). Only with this genotype (Rr), when crossed with a white geranium (rr), can you get:
- 50% offspring with Rr genotype (red flowers)
- 50% offspring with rr genotype (white flowers)
Thus, the genetic makeup of the red geranium parent is heterozygous for red flowers, Rr.