alleryWhich of these is NOT possible for the offspring of a TT × tt cross?
AAll TT homozygous tall
BAll Tt heterozygous tall
CGenotype matches one parent and not the other
DPhenotype tall in 100 percent of cases
Answer & Solution
Correct answer: A. All TT homozygous tall
1. The TT parent contributes only T gametes.
2. The tt parent contributes only t gametes.
3. Every fertilisation gives a Tt zygote.
4. So every F₁ offspring is heterozygous Tt and shows the dominant tall phenotype.
5. No offspring is homozygous TT because no t-free × t-free combination is possible.
6. Hence option B (all TT homozygous tall) is impossible from this cross.
_Source: syllabus Science Ch 9 'Heredity' (learncbse.in extract)_
Keep practising Unit 7B: Population Genetics & Hardy-Weinberg Evolution
Browse all Unit 7B: Population Genetics & Hardy-Weinberg Evolution questions for AP Biology, or explore more Biology topics.
Related questions
Evolution is best defined as the change occurring in living organisms that takes place:Which genetic disorder is given as an example of a condition that can be caused by a mutatA sudden change in a gene, such as a nucleotide shifting its position, is known as a:The stepwise movement of the ribosome along mRNA by a distance of one triplet codon is terThe amino acids brought in by tRNA are joined together by peptide bonds with the help of wOn a tRNA molecule, the sequence that is complementary to the codon on mRNA is called the:Which Indian-origin scientist received the 1968 Nobel Prize for his work on triplet codonsHow many nucleotides make up the triplet codon that codes for a single amino acid?