16.4 Sexual reproduction in humans

2026 Syllabus Objectives

Identify on diagrams and state the functions of the following parts of the male reproductive system: testes, scrotum, sperm ducts, prostate gland, urethra and penis
Identify on diagrams and state the functions of the following parts of the female reproductive system: ovaries, oviducts, uterus, cervix and vagina
Describe fertilisation as the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell)
Explain the adaptive features of sperm, limited to: flagellum, mitochondria and enzymes in the acrosome
Explain the adaptive features of egg cells, limited to: energy stores and the jelly coat that changes at fertilisation
Compare male and female gametes in terms of: size, structure, motility and numbers
State that in early development, the zygote forms an embryo which is a ball of cells that implants into the lining of the uterus
Identify on diagrams and state the functions of the following in the development of the fetus: umbilical cord, placenta, amniotic sac and amniotic fluid
Describe the function of the placenta and umbilical cord in relation to the exchange of dissolved nutrients, gases and excretory products between the blood of the mother and the blood of the fetus
State that some pathogens and toxins can pass across the placenta and affect the fetus

Humans, like all mammals, reproduce sexually. A new life begins when the nucleus of a male gamete fuses with a female one, forming a zygote.

The female reproductive system consists of several interconnected organs, each with specific functions:

Ovaries 🥚

Two oval-shaped organs that produce female gametes called eggs or egg cells
Eggs begin to be formed inside a girl's ovaries before she is born
At birth, she already has thousands of partly developed eggs inside her ovaries
When she reaches puberty, some of these eggs begin to mature (usually one at a time)

Oviducts (Fallopian tubes)

Tubes leading away from the ovaries towards the uterus
Do not connect directly to the ovaries but have a funnel-shaped opening just a short distance away
Lined with cilia that help to sweep the egg along
Have muscles in the wall that produce gentle rippling movements to move the egg

Uterus (womb)

Where a fetus develops before birth
Has very thick walls made of muscle
Relatively small (about the size of a clenched fist) but can stretch greatly during pregnancy
Has a thick, spongy lining called the endometrium

Cervix

Vagina

Key Point: The urethra, vagina, and rectum open quite separately to the outside in females.