Match Column I with Columns II and III. Column I Column II Column III Auxin Gibberella fujikuroi Abscission Ethylene Coconut milk Internodal elongation Abscisic acid Coleoptile tip Apical dominance Cytokinin Chloroplast Ripening Gibberellins Fruits Cell division

Auxin - Coleoptile tip - Apical dominance Auxin hormone is synthesised by the meristematic tissue at the tip of the stem, and it is responsible for cell enlargement, apical dominance and also prevention of abscission. F.W. Went demonstrated the existence and effect of auxin in plants. He did a series of experiments in Avena coleoptiles and concluded that a chemical diffusing from the tip of coleoptiles was responsible for growth. Thus, he named it, “Auxin” meaning ‘to grow”. Ethylene - Fruits - Ripening Ethylene is a gaseous plant hormone which acts as a growth inhibitor. This hormone is mainly concerned with maturation and ripening of fruits. Maximum synthesis of ethylene occurs during the ripening of fruits like apples, melons and bananas. It also brings abscission in senescent plant parts such as leaves, fruits and flowers. Abscisic acid - Chloroplast - Abscission Abscisic acid (ABA) is a growth inhibitor found in the chloroplast of plants, which promotes the process of abscission and senescence in leaves by causing loss of chlorophyll. Cytokinin - Coconut milk - Cell division Cytokinins are plant hormones produced in the root meristems, young leaves and developing fruits. It is found abundantly in the liquid endosperm of coconut (coconut milk). It promotes cell division or cytokinesis and has a negative effect on apical dominance. Gibberellins - Gibberella fujikuroi - Internodal elongation Gibberellins are phytohormones which bring about cell elongation of mainly the stem. Kurosawa observed Bakanae disease or foolish seedling disease in rice crops. This internodal elongation in rice was caused by fungus Gibberella fujikuroi . The active substance was identified as Gibberellic acid. Column I Column II Column III Auxin Coleoptile tip Apical dominance Ethylene Fruits Ripening Abscisic acid Chloroplast Abscission Cytokinin Coconut milk Cell division Gibberellins Gibberella fujikuroi Internodal elongation

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Science Standard 10>Chapter 16 - Plant and Animal Hormones>TEXTBOOK EVALUATION>Q 4

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plant hormones induce stem elongation in rosette plants.

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Important Questions on Plant and Animal Hormones

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Science Standard 10>Chapter 16 - Plant and Animal Hormones>TEXTBOOK EVALUATION>Q 5

The hormone which has a negative effect on apical dominance is _____.

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Science Standard 10>Chapter 16 - Plant and Animal Hormones>TEXTBOOK EVALUATION>Q 7

Beta cells of islets of Langerhans secrete _____.

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Science Standard 10>Chapter 16 - Plant and Animal Hormones>TEXTBOOK EVALUATION>Q 9

Decreased secretion of thyroid hormones in the children leads to _____. (Cretinism/Dwarfism)

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Science Standard 10>Chapter 16 - Plant and Animal Hormones>TEXTBOOK EVALUATION>Q 1

Match Column I with Columns II and III.

Column I	Column II	Column III
Auxin	Gibberella fujikuroi	Abscission
Ethylene	Coconut milk	Internodal elongation
Abscisic acid	Coleoptile tip	Apical dominance
Cytokinin	Chloroplast	Ripening
Gibberellins	Fruits	Cell division