Question

Length of pollen tube depends on the distance between

Options

• pollen grain and upper surface of stigma

• pollen grain on upper surface of stigma and ovule

• pollen grain in anther and upper surface of stigma

• upper surface of stigma and lower part of style

Answer 1

pollen grain on upper surface of stigma and ovule

Explanation - 

Once a pollen grain reaches on the stigma of the pistil, it germinates to form a pollen tube which grows down the style to reach the ovule present inside the ovary. So, the length of the pollen tube depends on the distance between the pollen grain on the upper surface of the stigma and the ovule.