Question

Which one of the following is not an antitranspirant?
a. PMA
b. BAP
c. Silicone oil
d. All the above

Answer 1

Antitranspirants are the chemicals used to reduce transpiration. Metabolic inhibitors and film-forming transpirants are the types of antitranspirants. PMA, silocone, aspirin, etc are the examples of antitranspirants.

Complete answer:
Antitranspirant are the compounds which are applied to the leaves of plants. They help in reducing the rate of transpiration. They are very useful for the plants as they preserve the plants from drying out too quickly. They also provide protection to the plants from salt burn and fungal diseases. The active excretion of hydrogen cation from the guard cells can be blocked by using antitranspirant. Stomatal closure can occur due to the presence of carbon dioxide and rapid acidification of the cytoplasm. Formation of these chemicals was first observed by Milbarrow in 1974.

Antitranspirants are mainly of two types: metabolic inhibitors and film-forming antitranspirants.
• Reduced stomatal opening and increase in leaf resistance to water vapour occurs by metabolic inhibitors. Examples of metabolic inhibitors are: phenylmercury acetate (PMA), Abscisic acid (ABA) and aspirin.
• A colorless film is observed on the leaf surface that allows diffusion of gases but not of water vapour by film-forming antitranspirants. For example: silicone oil, waxes.
• BPA is a chemical in the environment that harms the plants and also disrupts their growth.
From the above information we have found that BPA is not an antitranspirant.

Hence, the correct answer is option (B).

Note: To check the intake of potassium ion or induces loss of potassium ion from the guard cells antitranspirants are responsible for it. They have many applications on Christmas trees, on cut flowers, on newly transplanted shrubs. They have various advantages in horticulture, especially in the ornamental industry. They are also used to improve crop yield in drought affected areas.