OBJECTIVE LIFE SCIENCE
GENETICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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In a genetics laboratory, two heterozygous tall plants are crossed. If tall is dominant over short, what are the expected phenotypic results?
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100% Tall
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50% Tall, 50% Short
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75% Tall, 25% Short
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25% Tall, 75% Short
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Explanation:
Detailed explanation-1: -The expected genotype ratio when two heterozygotes are crossed is 1 (homozygous dominant) : 2 (heterozygous) : 1 (homozygous recessive).
Detailed explanation-2: -As shown in the figure a cross between two heterozygous tall plants results in 25% homozygous tall, 50% heterozygous tall and 25% dwarf plants.
Detailed explanation-3: -Answer and Explanation: Since a Tt heterozygous, tall plant produce with equal probabilities the gametes T and t, and the tt homozygous, short plant only t gametes, when they are crossed (Tt x tt) the progeny will be 50% tall (all genotypically Tt) and 50% short (all genotypically tt).
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