Question

A dwarf pea plant was treated with gibberellic acid (GA), it grew as tall as the homozygous tall pea plant. If this GA-treated plant is now crossed with a pure tall pea plant then the phenotypic ratio in the next generation is likely to be

• A. All dwarf.
• B. 50% dwarf, 50% tall.
• C. 75% tall, 25% dwarf.
• D. All tall.

Answer 1

The correct option is D All tall.

Pure recessive dwarf plant tt crossed with pure tall plant TT:
tt X TT ----------> tT (Heterozygous tall)
Thus, we will get all tall plants as a result of the cross. Gibberellic acid will cause the increase in length of shoot. But it cannot make any change in the genetic make up of the individual and thus the phenotype is not carried on to the next generation.