How does pollen tube growth facilitate fertilisation in flowering plants?

Pollen tube growth facilitates fertilisation in flowering plants by providing a pathway for sperm to reach the ovule.

In flowering plants, fertilisation is a complex process that involves the transfer of pollen from the male part of the plant (the anther) to the female part (the stigma). This process is known as pollination. Once the pollen grain lands on the stigma, it begins to germinate and grow a structure called a pollen tube. This growth is facilitated by the nutrients and signals provided by the stigma and style, the elongated part of the female organ.

The pollen tube acts as a conduit for the sperm cells to travel down towards the ovule, which is located in the ovary at the base of the style. The growth of the pollen tube is directed by chemical signals from the ovule. This ensures that the pollen tube grows in the right direction and reaches the correct location for fertilisation to occur.

Once the pollen tube reaches the ovule, it penetrates the ovule through a small opening called the micropyle. The sperm cells then travel down the pollen tube and into the ovule, where they fertilise the egg cell to form a zygote. This zygote will eventually develop into a seed, and the ovary will develop into a fruit to protect and disperse the seed.

In summary, the growth of the pollen tube is a crucial step in the fertilisation process in flowering plants. It provides a pathway for the sperm cells to reach the ovule, and its growth is carefully controlled and directed by chemical signals from the ovule. Without the growth of the pollen tube, the sperm cells would not be able to reach the egg cell, and fertilisation would not occur.