Question

The peg formation in groundnut are positively

• A. Chemotropic
• B. Thigmotropic
• C. Geotropic
• D. Hydrotropic

Hint:

The groundnut peg is the structure that carries the fertilized ovary downwards to bury itself in the soil where the pod develops. This downward growth is a response to gravity, known as positive geotropism (or gravitropism).

Answer 1

The Correct Option is C

In groundnut (Arachis hypogaea), after fertilization of the flower, a specialized stalk-like structure called a "peg" (or gynophore) develops from the base of the ovary. This peg, carrying the fertilized ovules at its tip, elongates and grows downwards into the soil. The fruit (pod) then develops underground. This downward growth of the peg into the soil is a classic example of positive geotropism. Let's define the terms:
Chemotropic: Growth or movement in response to a chemical stimulus.
Thigmotropic: Growth or movement in response to touch or contact.
Geotropic (or Gravitropic): Growth or movement in response to gravity. Positive geotropism is growth towards the direction of gravity (downwards), like roots and the groundnut peg. Negative geotropism is growth away from gravity (upwards), like shoots.
Hydrotropic: Growth or movement in response to water or moisture. The primary directional cue for the groundnut peg's downward growth is gravity. Geotropic