Question

The number of pollen grains, produced by each head inflorescence of family Asteraceae which has 10 actinomorphic flowers and if each anther produces 20 pollen grains are
A. 300
B. 800
C. 500
D. 1000

Answer 1

Hint: Stamen is the male gametophyte in a plant whereas the ovary is the female reproductive gametophyte. The pollen from the stamen travels via the style into the ovary to fertilize it. The anthers are the part of stamen carrying the pollen grains. Asteraceae has five anthers.

Complete answer:
Asteraceae, also called Compositae, includes herbs, shrubs, and trees distributed throughout the world. It is an exceedingly widespread family of flowering plants with more than 23,600 currently accepted species.

An actinomorphic flower is a type of flower that possesses radial symmetry that is a flower which can be divided by more than one line passing through the middle of the flower, into two equal parts are known as actinomorphic flowers.
Example: In Gustavia (Lecythidaceae), species of Myrtaceae, and species of Rubiaceae.

A head / capitulum inflorescence is a short dense spike in which the flowers are borne directly on a peduncle, giving the appearance of a single flower. Example- dandelion
This results in a grouping of small flowers to appear as a single flower.
In many members of the Asteraceae e.g., sunflowers the outer flowers have a well-developed zygomorphic corolla, and the inner (disk) flowers have a small actinomorphic corolla.

The inner disk flowers generally are complete.
In family Asteraceae, the flowers are arranged in disc florets. Each flower contains 5 anthers.
Therefore, 10 flowers will have $10 \times 5 = 50$ anthers.
Pollen grains in 1 anther are 20
Therefore, pollen grains in 50 anthers will be $50 \times 20 = 1000$

Hence, The correct answer is option (D).

Note: Stamen is the pollen-producing part of a flower and anther is the part of stamen where pollen is produced. The collection of stamens is called androecium. The stamen has the other part called stalk (filament). Stalk holds the anther on its tip. The pollens are in the microsporangia of the anther where they undergo meiosis to become haploid cells.