If the cross of a red-flowered plant with a white flowered plant produces a pink flowered plant, this is an example of

1. Analyze the question A red-flowered plant is crossed with a white-flowered plant, and the offspring are pink. The pink colour is neither parent's colour. It is a blend, an intermediate between the two.

2. Explain the concept

• Complete dominance: one allele completely masks the other (e.g., tall × short gives all tall).
• Incomplete dominance: neither allele fully dominates, so the heterozygote shows an intermediate (blended) phenotype. Example: red (RR) × white (WW) gives pink (RW), as in Mirabilis jalapa (four o'clock plant) or snapdragons.
• Codominance: both alleles are fully expressed at the same time, so both traits show side by side without blending. Example: a red and white speckled flower, or the AB blood group.
• Mutation: a sudden change in the genetic material.
• Linkage: genes located on the same chromosome that tend to be inherited together.

3. Solution Let R = red allele and W = white allele.

• Parents: RR (red) × WW (white)
• Gametes: R and W
• F1 generation: all RW, which are pink

The pink colour is a blend of red and white, so neither allele is fully dominant. The F1 plants are intermediate in appearance. If the F1 are crossed (RW × RW), the F2 ratio is 1 red : 2 pink : 1 white. That 1:2:1 phenotypic ratio is the signature of incomplete dominance.

Why not the others?

• A (codominance): this would give red and white patches in the same flower, not a uniform pink.
• C (mutation): nothing suggests a sudden genetic change. The result is predictable from the cross.
• D (linkage): this concerns genes inherited together on one chromosome, not blending of a single trait.

4. Answer **B. incomplete dominance.

5. Exam tip

• Blend or in-between → incomplete dominance.
• Both shown side by side → codominance.

Think of "incomplete" as "the dominant allele doesn't finish the job", so you get a mix, like mixing red and white paint to make pink.