1.1 Circulatory systems

Question 1

Define diffusion

Answer 1

The movement of particles or ions from an area of high-low concentration down a concentration gradient.

Question 2

State 4 factors affecting rate of diffusion

Answer 2

• Temp
• Concentration
• Diffusion distance
• Size of molecules

Question 3

How does concentration affect diffusion

Answer 3

Higher concentration - more chance of particles colliding - therefore increased rate of diffusion

Question 4

Example of organism with no circulatory system

Answer 4

Amoeba

Question 5

Why do animals have a circulatory system?

Answer 5

For faster diffusion (higher blood pressure allows for this) as rate of diffusion through body not sufficient to keep up with high metabolic rate.

Question 6

What does MASS FLOW SYSTEM transport?

Answer 6

Water and solutes - oxygen and glucose transported

Question 7

How does an open cicrulatory system work?

Answer 7

• Heart contracts - blood pumped into cavities surrounding organs/cells.
• Substances diffuse between blood and cells
• Heart relaxes (diastole) - blood drawn back into the heart through small valve-like openings - ostia.

Question 8

How does blood flow in a closed circulatory system?

Answer 8

• Blood enclosed in vessels,
• Travels from heart around body back to heart

Question 9

How does blood flow in a single circulatory system?

Answer 9

• Flows through body once for each complete circuit.

Question 10

How does blood flow in a double circulatory system?

Answer 10

• Flows round body twice for each complete circuit.
• In humans RV pumps deoxy blood to lungs, oxy blood returns to heart then pumped around body again.

Question 11

What does a double circulatory system allow for?

Answer 11

A higher metabolic rate