Question

Name the organ/part of a plant which shows:

1. Positive hydrotropism
2. Positive phototropism
3. Negative geotropism
4. Positive chemotropism

Answer 1

• (i) Positive hydrotropism (growth towards water): Roots. Roots exhibit positive hydrotropism, growing towards sources of water.
• (ii) Positive phototropism (growth towards light): Stems (shoot). Stems show positive phototropism, growing towards sunlight.
• (iii) Negative geotropism (growth away from gravity): Stems (shoot). Stems typically exhibit negative geotropism, growing upwards against the pull of gravity.
• (iv) Positive chemotropism (growth towards chemicals): Roots and pollen tubes. Roots grow towards beneficial chemicals in the soil (positive chemotropism), and pollen tubes grow towards the ovule (positive chemotropism).