Lifestyle, Health and Risk

Question 1

Why do animals have a circulatory system?

Answer 1

• They have a small surface area to volume ratio
• So without a circulatory system diffusion would be too slow
• Mass flow of oxygen to cells around the body
• Fast movement of blood to cells

Question 2

How does the circulatory system of many mammals help to transport oxygen and remove carbon dioxide from the body?

Answer 2

• Double circulatory system
• Heart pumps blood long distances
• At high pressures

Question 3

Explain why a mammalian heart is divided into a right and left side?

Answer 3

• To separate oxygenated and deoxygenated blood
• There are different pressures to be maintained. The left side is under higher pressure than the right side since it carries blood to the body cells
• It allows mass flow of oxygen to body cells

Question 4

Explain how the dipole nature of water is essential for living organisms?

Answer 4

• Water forms hydrogen bonds with other water molecules
• This makes it cohesive
• Substances can dissolve in it
• It is used as a transport medium e.g xylem vessels, blood

Question 5

Explain how the structure of an artery is related to it’s function?

Answer 5

1. It has elastic fibres in it’s wall
   - To recoil
   - Maintain a high blood pressure
2. It has folded endothelium
   - Which allows stretching to cope with high blood pressure
3. It has smooth muscle
   - To contract
4. It has collagen
   - To avoid damage

Question 6

What is meant by ‘correlation’?

Answer 6

When there is a relationship between two variables

Question 7

What is meant by ‘causation’?

Answer 7

When a change in one variable results in a change in another variable