Q25 of 26 Page 7

What is a plant hormone? Name four plant hormones. State one function of each.

( CBSE 2015)

Plant hormones (also known as phytohormones) are chemicals that regulate plant growth.

4 Plant hormones:
(a) Auxins: Influence cell enlargement, bud formation and root initiation. Also promotes apical dominance.


(b) Cytokinins: Influence cell division and shoot formation.


(c) Gibberellins: Stimulate cell elongation and initiate mobilization of storage materials in seeds during germination.


(d) Ethylene: Stimulates the ripening of fruit and initiates abscission of fruits and leaves.

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22 A) Which plant hormones is present in greater concentration in the areas of rapid cell division?
B) Give one example of a plant growth promoter and a plant growth inhibition. (CBSE 2012, 2011) 23

State the role of the brain in reflex action.  ( CBSE 2008)

 24

(a) i) Draw a neat diagram of human brain and ii) Label Medulla and Cerebellum iii) Write the functions of the above-mentioned parts (b) ”Both overproduction and underproduction of Growth hormone lead to disorders in the body.” Explain.
( CBSE 2017, 2015)

 26

Mention one function for each of these hormones:

(a) Thyroxine, (b) Adrenaline, (c) Insulin, (d) Growth hormone, (e) Testosterone

( CBSE 2005)