Question

Even after killing the generative cell with a laser beam, the pollen grain of flowering plant germinates and produces normal pollen tubes because
A) Laser beam stimulates pollen germination and pollen tube.
B) The laser beam does not damage the region from which the pollen tube emerges.
C) The contents of the killed generative cell permit germination and pollen tube growth.
D) The vegetative cell has not been damaged.

Answer 1

Red light laser has spectral range of 660-680 nm which are considered as strong absorption bonds of chloroplasts and chromoplasts. So this light induces growth in vegetative cells.

Complete Answer:
- Germination is the process by where any organism grows from a seed which is also called sprouting.
- After pollination, pollen grain germinates from flowering plants. They are fully dehydrated before being released to facilitate their dispersal from one plant to another.
- Pollen grains are in a protective coat containing several cells and one of these cells is a tube cell.
- Every pollen grain contains vegetative cell, and a generative cell which further divides into two sperm cells.
- Once these pollen grain lands on the stigma, it takes up water and germinates. Vegetative cell grows big in size and comes out of the pollen grain to form a pollen tube and divides into 2 male gametes to the embryo sac.
- Thus if the laser beam kills the generative cell, the pollen grain of flowering plant germinates and produces normal pollen tubes because the vegetative cell has not been damaged.

Thus, the correct answer is option D.

Note: In the $19^{th}$ century, Giovanni Battista Amici, microscopist, and botanist, first discovered pollen tubes. They are used as a structure base for understanding plant cell behaviour.