Question

If a homozygous tall plant is crossed with homozygous dwarf plant, the offsprings will be

• A. All tall plants
• B. All dwarf plants
• C. Half tall plants
• D. Half dwarf plants

Answer 1

Answer: (A)

All tall plants

A cross between two homozygous varieties always obtains all dominant offspring. During a cross between homozygous tall (TT) and homozygous dwarf (tt), the tall parent produces all gametes with “T allele” and dwarf parent produces all gametes with “t allele”. Random fusion of gametes carrying “T” and “t” produces all zygotes carrying “Tt” genotype. According to the law of dominance, the presence of one copy of allele for tallness (“T”, the dominant allele) is sufficient to mask the expression of an allele of dwarfism (“t”, the recessive allele). Therefore, the progeny with “Tt” genotype would exhibit tall phenotype.

Thus, the correct answer is option A.