Question

Name various plant hormones. Also give their physiological effects on plant growth and development

NCERT Class X
Science - Exemplar Problems

Chapter_Control and Coordination

Answer 1

1] auxin - it promotes plant growth and fruit growth
2] gibberlins-  it helps in fruit growth
3] cytokinins -its function is same as gibberlins
4] abscisic acid- it inhibits plant growth and is also responsible for the falling of leaves fruits and flowers

Answer 2

Plants also perform chemical coordinatiòn for various activities with the help of hormones. These are the chemical compounds released by stimulated cells that diffuse to various locations in plants performing different functions. These hormones produced by plants are also called as phytohormones.

Different types of hormones produced by plants are: Auxin, Gibberellins, Cytokinins, Abscisic acid Ethylene

Auxin

▪Synthesised in the young tip of roots and shoots. diffuses towards the shady side of plant, which stimulates the cells to grow longer, resulting in bending of shoot towards light.

▪Promotes cell elongation and division.

▪Plays important role in formation of roots and seedless fruits.

Giberellins

▪Helps in growth of stem and flower.

▪Helps in germination of seed

Cytokinins

▪Promote cell divsion and delay leaf aging.

▪Also stimulate leaf expansion

Abscisic acid

▪Growth inhibitor

▪Reverses the growth promoting effects of auxins and gibberellins.

Ethylene

▪Promotes transverse growth.

▪Essential for fruit ripening, promotes senescence and abscission of leaves.