1.1 Heart and Circulation (2)

Question 1

Closed Circulatory System

Answer 1

Blood is enclosed within tubes.
Generate H.B.P (Travels faster + more efficient at delivering substances around the body)
• Blood leaves heart under pressure # arteries # arterioles # capillaries
• Capillaries come in large numbers. They exchange substances between the blood and cells.
• After passing through capillaries # blood goes back to the heart via venules # veins
• Valves in the veins ensure that blood only flows in one direction.

Question 2

Single Circulatory System

Answer 2

Heart pumps deoxygenated blood # gills• Gaseous exchange (diffusion of CO2 from blood to H2O that surrounds the gills, and diffusion of O2 from H2O
into the blood)
• Blood leaves gills # rest of body # heart

Question 3

Double Circulatory System

Answer 3

Right ventricle pumps deoxygenated blood to the lungs where it receives oxygen.• The oxygenated blood then returns to the heart to be pumped a second time ( by the left ventricle) out to the
rest of the body.

Question 4

What is Diffusion?

Answer 4

Diffusion: Movement of molecules or ions from an area of high concentration to an area of low concentration.

Question 5

Why have a heart and circulation?

Answer 5

Need to move substances around the body such as carbon dioxide, oxygen, and digestive organisms.

In unicellular organisms this is given to tissue cells through diffusion.

Question 6

Why do Mammals have a high metabolic rate?

Answer 6

Mammals have a high metabolic rate because oxygen and food substances required for metabolic processes need to be delivered rapidly to cells.

Question 7

Can Multicellular organisms use diffusion?

Answer 7

Multicellular organisms are too large for diffusion therefore need blood to carry substances around the body.

Heart as a pump (Circulatory system