AP BIOLOGY

HEREDITY

MONOHYBRID CROSS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A tall pea plant (TT) is crossed with a short pea plant (tt). What percentage of the offspring will be tall?
A
100%
B
75%
C
50%
D
25%
Explanation: 

Detailed explanation-1: -Here, we see that all the F1 offsprings produced on crossing a TT tall pea plant with a tt short pea plant are heterozygous Tall ( Tt). i.e., 100% of tall offsprings.

Detailed explanation-2: -So, the correct option is ‘50%’.

Detailed explanation-3: -F2 Genotypic ratio =1 pure tall (TT) : 2 heterozygous tall (Tt) : 1 pure dwarf (tt); thus, the ratio of pure tall to pure short plants will be 1:1.

Detailed explanation-4: -This shows that ratio of pure tall (TT) to pure short (tt) is 1:1.

Detailed explanation-5: -In a cross between heterozygous tall plants (Tt) and a homozygous dwarf plant (tt), the ratio in the offspring shall be 1 tall : 1 dwarf. This is because the heterozygous plant will make two types of gametes, one type having T allele and the other having t allele.

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