Specialised Exchange System

Question 1

What does our specialised exchange system do ?

Answer 1

• Nutrients (glucose/ amino acids/ fatty acids) are taken in to provide energy & raw material for growth
• Oxygen is taken in to release energy from glucose in respiration
• Waste products of metabolism (carbon dioxide, urea) must be removed

Question 2

Which organisms do not need a specialised exchange system and why?

Answer 2

• Single-celled Organisms
• Surface area: Volume is larger
• Distance between cells and exchange surface is very small
• Low metabolic activity
• No need for a specialised exchange system

Question 3

Why do we have a specialised exchange system?

Answer 3

• LARGER the organisms the SMALLER the SA:VOL
• Distance between external exchange surfaces and volume of respiring tissues increases
• Diffusion is not efficient enough to provide oxygen for metabolic activities and to remove wast carbon dioxide
• Specialised transport system necessary to ensure faster rate of diffusion

Question 4

How do you calculate Surface Area to Volume ratio?

Answer 4

SA of 1 face= Length x Length
SA of cube= SA of 1 face x Number of Sides
Volume of cube= Length x Length x Length
SA to VOL ratio= SA:Vol