AP BIOLOGY

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CELL DIVISION

MEIOSIS AND GENETIC VARIATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a certain breed of flowers, red petals are incompletely dominant to white petals; the heterozygote is pink. Axial flowers are completely recessive to terminal flowers. If a red petal, axial flowered plant is bred to a pink flowered plant that is true-breeding for terminal flowers, what is the expected phenotypic ratio in their offspring?
A
The offspring will be 50% red petal, terminal flowers and 50% pink petal, terminal flowers.
B
The offspring will be 50% red petal, axial flowers and 50% red petal, terminal flowers.
C
The offspring will be 50% pink petal, axial flowers and 50% pink petal, terminal flowers.
D
The offspring will be 25% red petal, terminal flowers to 50% pink petal, terminal flowers to 25% white petal, terminal flowers.
Explanation: 

Detailed explanation-1: -Incomplete dominance The F1-hybrid plants have a different phenotype (pink flowers) than either of the true-breeding parents. This is an example of incomplete dominance. When the F1-hybrid plants are self-fertilized, both parental phenotypes (red flowered plants and white flowered plants) reappear in the F2 generation.

Detailed explanation-2: -The crossing of a red flowered plant and a white flowered plant produces all the offspring with pink flowers. This cross illustrates red and white exhibit incomplete dominance.

Detailed explanation-3: -Red flower colour (R) is incompletely dominant over white (r), the heterozygote being pink. Plant having genotype of TtRr is self pollinated.

Detailed explanation-4: -Answer and Explanation: Answer is 50%. 50% of the progenies will have pink flowers.

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