the circulatory system

Question 1

features of arteries

Answer 1

narrow tube to keep high pressure of blood flow
thick elastic layer of muscle fibres

Question 2

features of vein

Answer 2

Valves to prevent back flow
thin flexible wall
low pressure
wide tube

Question 3

Plasma

Answer 3

straw coloured fluid carrying glucose, CO2 and urea

Question 4

Red blood cells

Answer 4

packed with haemoglobin which binds with oxygen in lungs and releases it in tissues

Question 5

Why are red blood cells shaped like biconcaves

Answer 5

to increase the surface area for diffusion