Sex Determination

What is Sex Determination?

In humans, chromosomal sex is determined by one pair of chromosomes called the sex chromosomes. The typical female combination is XX and the typical male combination is XY. Because a female has two X chromosomes, every egg carries an X; because a male has one X and one Y, half of the sperm carry X and half carry Y. The sperm therefore supplies the chromosome that determines whether the offspring is XX or XY, and each fertilisation has an approximately equal probability of each outcome, independently of any previous fertilisation.

This definition is part of the Inheritance chapter in Cambridge O Level Biology.

Concepts related to Sex Determination

• sex chromosome
• gamete
• Meiosis
• probability