Question

Choose the correct answer from the alternatives given.
The plant hormone that causes cell elongation is:

• A. citric acid
• B. indole 3-acetic acid
• C. ethylene
• D. abscisic acid

Answer 1

The correct option is B indole 3-acetic acid

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers.

So, the correct option is 'indole 3-acetic acid'.