Q 01/05

How many bones are in the adult human body?

A) 60

B) 206

C) 700

D) 2,100

Answer · why

B) 206

206, far fewer than a newborn has, because many of a baby's bones fuse together as the body grows.

Q 02/05

What is the largest organ in the human body?

A) Skin

B) Stomach

C) Liver

D) Kidneys

Answer · why

A) Skin

Skin keeps water in and germs out, which is why burns over a large area bring dangerous fluid loss and infection.

Q 03/05

Which type of blood cell is responsible for fighting infections?

A) Red blood cells

B) White blood cells

C) Platelets

D) Reticulocytes

Answer · why

B) White blood cells

White blood cells; the pus in an infected wound is largely made of ones that died fighting the infection.

Q 04/05

What is the hardest substance in the human body?

A) Bone

B) Fingernails

C) Cartilage

D) Tooth enamel

Answer · why

D) Tooth enamel

Tooth enamel, which can't regrow once damaged, because the cells that made it die off around the time the tooth erupts.

Q 05/05

Which chamber of the heart pumps blood to the entire body?

A) Right atrium

B) Right ventricle

C) Left ventricle

D) Left atrium

Answer · why

C) Left ventricle

The left ventricle, whose walls are much thicker than the right ventricle's because it pushes blood round the whole body, not just the lungs.