Drugs that affect the central nervous system causing mental or behavioral changes are called:

Psychoactive Drugs.

Explanation: A psychoactive drug can be defined as the chemical substance that that acts primarily on the central nervous system of the brain.

It also alters the various functions of the brain which changes the mood, perception, consciousness and behavior of the person temporarily.

Example: coffee, alcohol, cannabis, and other medication.

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.