A Level Biology C8 Recap

What is the term used to describe a circulatory system where blood never leaves the vessels?

• Restricted

• Closed

• Contained

• Internal

Answer explanation

A closed circulatory system is where blood never leaves the vessels. The opposite is an open circulatory system, where blood can leave the vessels.

Which blood vessel pumps oxygenated blood to the body from the heart?

• Aorta

• Pulmonary vein

• Vena cava

• Pulmonary artery

Which muscles are present in the tunica media layer of blood vessels?

• Elastic muscles

• Skeletal muscles

• Cardiac muscles

• Smooth muscles

Thick tunica media, small lumen, carries oxygenated blood. Which blood vessel does this describe?

• Veins

• Atriums

• Arteries

• Capillaries

How do capillaries allow exchange of materials between blood and organs? (choose all that apply)

• Active transporters in capillary walls

• Diffusion across capillary walls which are one cell thick

• Protein channels in capillary walls

• Gaps between endothelial cells allow blood components to seep through

Answer explanation

Some molecules diffuse through the endothelial cells while others squeeze through small gaps between endothelial cells

What prevents blood from flowing backwards in vessels?

• Valves allow blood to only flow in one direction

• Smooth muscles only contract in one direction

• Gravity pulls blood in one direction

• Electrical impulses push blood in one direction in vessels

Answer explanation

Valves open when blood flows in the right direction and close to prevent backflow.

Elastic fibers allow blood vessels to expand. What component in the vessel walls provides strength to the blood vessels?

• Smooth muscles

• Collagen fibers

• Endothelial cells

• Plasmodesmata

Red blood cells do not contain a nucleus. What is the term used to describe this morphological feature?

How many chambers in the heart does deoxygenated blood pass through?

• 1

• 2

• 3

• 4

Answer explanation

Deoxygenated blood passes through two chambers, the right atrium and right ventricle.

The highest pressure in the heart can be found in which chamber(s)? (choose all that apply)

• Right atrium

• Right ventricle

• Left atrium

• Left ventricle