Question

A pollen grain is
A. First a haploid and then a diploid structure
B. First diploid and then a haploid structure
C. A diploid structure
D. A haploid structure

Answer 1

Pollen grains are microscopic structures that carry the male reproductive part of plants.
The inner side of the grain consists of cytoplasm along with the tube cell which later becomes the pollen tube and the generative cell which helps in releasing the sperm nuclei. The outer shell of the pollen grain is made of two layers.

Complete answer:
Pollen is a powdery substance that consists of pollen grains which are known to be male microgametophytes of seed plants and they produce male gametes (sperm cells). If a pollen grain lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Pollen grains mainly represent the male part of the reproductive process in plants and trees. After the formation of the four haploid microspores occurs it fuses to form pollen grain and the development of the pollen grain walls starts. Hence pollen grain is a haploid structure. Individual pollen grains are small enough to require magnification. Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of another in and this process is known as cross-pollination. In the case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower.
So, the correct option is option D-A haploid structure.

Note: Bee pollen for human consumption is marketed as a food ingredient and as a dietary supplement. The largest constituent is carbohydrates, with protein content ranging from 7 to 35 percent depending on the plant species collected by bees. Honey produced by bees from natural sources contains pollen derived p-coumaric acid, an antioxidant and natural bactericide that is also present in a wide variety of plants and plant-derived food products.