$(a)$ What is $DNA$? Where is it found?
$(b)$ Name the functional segment of $DNA$.

(N/A) $DNA$ stands for Deoxyribonucleic acid. It is a complex molecule that contains the genetic instructions necessary for the development, functioning, growth, and reproduction of all known organisms. In a non-dividing cell, $DNA$ is found within the nucleus as a component of chromatin material. When the cell prepares to divide, this chromatin material condenses and organizes into structures called chromosomes.
$(b)$ The functional segments of $DNA$ are known as genes. Genes are the basic units of heredity and are responsible for the transmission of traits from parents to offspring.