Question

A pollen tube grows down the style because

• A. it helps in fertilization.
• B. it takes nutrients from the style.
• C. filiform apparatus of synergids attracts the pollen tube.
• D. of chemical attraction.

Answer 1

The correct option is D of chemical attraction.

• The pollen tube begins to grow when the pollen grain lands on the stigma of a flower and grows through the style till it reaches the ovule inside the ovary.
• Once a pollen grain settles on a compatible pistil, it germinates in response to a sugary fluid secreted by the mature stigma of certain plants.
• The lipids at the surface of the stigma stimulate the growth of the pollen tube of a compatible pollen.
• During its journey through the pistil, the pollen tube is shown to respond to various guidance signals, which are a combination of chemical and shows chemotropism.

Thus, the correct answer is option D.