Q 01/05

Roughly what percentage of an adult human's body weight is blood?

A) 7%

B) 12%

C) 18%

D) 25%

Answer · why

A) 7%

7% is the textbook figure: blood accounts for roughly 7 to 8 per cent of adult body weight, and its density is only slightly greater than water's.

Q 02/05

Roughly how much blood does the average adult have?

A) About 2 litres

B) About 5 litres

C) About 8 litres

D) About 12 litres

Answer · why

B) About 5 litres

About 5 litres of blood circulate in a typical adult; women average a little less than men, and the volume rises markedly during pregnancy.

Q 03/05

What is the straw-yellow liquid that makes up about 55% of blood?

A) Serum albumin

B) Lymph

C) Plasma

D) Hemoglobin

Answer · why

C) Plasma

Plasma is the straw-coloured fluid fraction of blood; serum is the name for plasma with the clotting proteins removed, and both are mostly water.

Q 04/05

Which iron-containing protein in red blood cells carries oxygen?

A) Myoglobin

B) Fibrinogen

C) Albumin

D) Hemoglobin

Answer · why

D) Hemoglobin

Hemoglobin is a globin protein carrying iron-containing haem groups; it gives red cells their colour and makes up roughly a third of each cell's weigh...

Q 05/05

How many oxygen molecules can a single molecule of the red cells' oxygen-carrying protein bind?

A) 4

B) 1

C) 2

D) 3

Answer · why

A) 4

4 is the maximum: each of the protein's four haem groups binds one oxygen molecule, and the reversible, cooperative binding is what makes transport ef...