Question

In a breeding experiment, tall pea plants (TT) are crossed with dwarf pea plants (tt). If the resulting $F_1$ plants are crossed with dwarf plants, the progeny consists of

• A. All tall plants
• B. 3 tall : 1 dwarf plant
• C. All dwarf plants
• D. 1 taIl : 1 dwarf plant

Answer 1

Answer: (D)

• According to the law of segregation, the dominant (T) and recessive (t) alleles present in heterozygous tall (Tt) plant in F${}_1$ generation would segregate and deliver singly to gametes.
• Thus, it will make two types of gametes: 50% with “T” and 50% with “t”. The homozygous dwarf (tt) plant will produce a single type of gametes: all with “t”. Random fusion of these gametes will produce tall and dwarf progeny in 1 Tt :1 tt ratio.
• Only a cross between pure breeding plants obtains a uniform progeny of dominant or recessive characters, based on the genotype of pure-breeding parents.
• Thus, the correct answer is option D.