Formative Practice 5.3 (Form 5 Biology Textbook Exercise and Answer)

Question 1:
State one application for each of these phytohormones in the field of agriculture.
(a) Gibberellin
(b) Cytokinin
(c) Auxin

The use of phytohormones in agriculture:
• Gibberellin promotes rapid elongation of flower stems.
• Cytokinins promote cell division and differentiation in tissue culture technique.
• Auxins produce seedless fruit via parthenocarpy.

Question 2:
Based on the statement below, what is hormone X? Explain the role of hormone X when the surrounding temperature increases.

With hormone X, plants can retain their water content.

Hormone X is abscisic acid. When the surrounding temperatures increase, more water will be lost via transpiration through the stomata. This will lead to the concentration of abscisic acid to be high in the leaf, which leads to the closing of stomata and maintain the water content in leaves.

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