Pollen Tube Advantage in Fertilisation

The formation of a pollen tube is a crucial step in the fertilisation process of flowering plants. Its primary function is to act as a conduit.

• The pollen tube grows from the pollen grain, after pollination, down through the style towards the ovary.
• This tube facilitates the direct transfer of the male germ-cells (gametes) contained within the pollen grain.
• The male germ-cells travel through the pollen tube directly to the ovule inside the ovary where fertilisation occurs.

Reasoning for Correct Option

Option C correctly states that the pollen tube ensures the direct transfer of the male germ-cell to the ovary. This mechanism is highly advantageous because:

• It provides a specific and efficient pathway, minimizing the distance the male gametes need to travel.
• It prevents the wastage of valuable male gametes, as they are delivered directly to the site of fertilisation.

Why Other Options Are Incorrect

• Option 1 is incorrect: While attachment to the stigma is necessary, the pollen tube's main role isn't firm attachment or facilitating *only* self-pollination; it's about reaching the ovule for fertilisation.
• Option 2 is incorrect: The pollen tube's function is gamete transport, not releasing nutrients for the ovule. Nutrient supply comes from the parent plant or stored reserves within the seed structures.
• Option 4 is incorrect: The ovary contains ovules with egg cells, but it does not actively release egg cells towards the pollen. The movement is from the pollen grain towards the ovule via the pollen tube.

Therefore, the key functional advantage lies in the targeted and efficient delivery of male gametes.