Short answerModerate1 mark
7(a)
A homozygous tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf (t) plant bearing white (r) flowers:
Mention the phenotypes of the offsprings obtained in F2 generation.
Topic: Phenotypes of the F2 generation
Previous-year question practice database
Answer
Exam answer
FOUR phenotypes appear:
- TALL with RED flowers
- TALL with WHITE flowers
- DWARF with RED flowers
- DWARF with WHITE flowers
Explanation
Name all FOUR. Listing only the two parental types is the commonest error.
THE TWO NEW COMBINATIONS — TALL-WHITE and DWARF-RED — are the important ones, because neither appeared in the parents nor in the F1 generation. Their appearance is the whole PROOF of INDEPENDENT ASSORTMENT, and an answer that omits them has missed what the question is really about.
This is also why Mendel used a DIHYBRID cross to establish that law: a monohybrid cross following one character could never reveal it.
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S. Haemophilia and Albinism
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