For approximately how many days does menstruation last in human females?

Write true or false for the statement: If the egg is not fertilized,it lives for about one day.

The pistil is intact. Cross-pollination has occurred,leading to fertilization and the formation of fruit. In a bisexual flower,despite the young stamens being removed artificially,the flower produces fruit. Provide a suitable explanation for the above situation.

Describe sexually transmitted diseases (STDs) and mention the ways to prevent them.

$(i)$ $(a)$ Write the full form of $DNA$.
$(b)$ State the role of $DNA$ in the cell nucleus.
$(c)$ What will be the after-effect if the information of the $DNA$ is changed?
$(ii)$ Explain the importance of $DNA$ copying in reproduction.

What is produced by the fusion of a male gamete and a female gamete?