Question

Which of the following best describes the function of pollen grain tube?

Answer 1

Answer:

The function of the pollen tube is to carry male gametes towards the ovary through stigma and style. It enters the ovule through the micropylar end and enters the synergid cell present next to the egg cell. The Filiform apparatus guides the entry of the pollen tube into synergies.

Answer 2

The pollen tube is a carrier that transports male gametes (sperm cells) from a male gametophyte to a female gametophyte during double fertilisation, which leads to seed development.

• The pollen tube in angiosperms is siphonogamous i.e fertilisation is accomplished by means of a pollen tube.
• The germination process begins when a pollen grain is deposited on a compatible stigma using self-incompatibility mechanisms. 
• Wind, water, and pollinators help carry pollen grains to the female gametophyte.
• The pollen grain undergoes a conformational shift during this process, causing a part of it to protrude outwardly, forming a tube-like structure known as the pollen tube.
• The pollen tube is a thread-like structure that stretches from the pollen shell to the tip.
• In simple terms, the pollen tube's role is to transport male gametes (two sperm nuclei) to the ovary via the stigma and style. It enters the ovule via the micropylar end and travels to the synergid cell close to the egg cell.
• The pollen tube is guided into synergids by the Filiform apparatus and one sperm nucleus fuses with the egg cell in the egg chamber of the ovary to form a diploid zygote and the other one fuses with the secondary nucleus (Polar nucleus) to develop into a triploid endosperm tissue. This is termed double fertilisation.