Question

Name the movement which causes 'X' and 'Y' to grow downwards and upwards respectively.

Answer 1

The downward growth of roots ('X') is called geotropism (or gravitropism), which is how plants grow in response to gravity. Gravity causes the roots to grow downwards.The upward growth of the stem ('Y') is called phototropism, which is how plants grow in response to light. The stem grows upwards towards light.

Answer 2

Plant hormones involved in the following processes:1. Leaf abscission: Abscisic acid (ABA) induces leaf fall. ABA promotes leaf senescence and abscission.2. Rapid cell division: Cytokinin stimulates rapid cell division, especially during growth. Cytokinins also delay leaf senescence.

Answer 3

The sensitive plant, *Mimosa pudica*, reacts quickly to touch by moving its leaves. This reaction, called thigmotropism, is the plant's way of responding to physical contact.\flushleftHow the Touch Signal Works:
1. Touching the plant's leaves causes a shift in the internal water pressure of leaf cells. This happens because water moves out of compartments within certain leaf cells. 2. The change in water pressure makes the leaflets fold. The fast movement results from the plant cells reacting to the touch through changes in ion levels and water flow.3. This reaction helps protect the plant from animals that eat plants. The quick leaf movement makes the plant seem less appealing to these animals.

Answer 4

Auxin, a plant hormone, is produced at the shoot tip.

Auxin's Role in Bending Towards Light:
- Auxin facilitates phototropism, the growth response to light. When light illuminates a plant asymmetrically, auxin concentrates on the shaded side.
- This higher auxin concentration stimulates cell elongation on the shaded side.
- This uneven growth causes the plant to bend towards the light.