1.1.1 - The Need For A Circulatory System

Question 1

What Do The Cells Of All Living Organisms Need A Constant Supply Of?

Answer 1

Reactants for metabolism. E.g. Glucose and oxygen.

Question 2

How Do Single Celled Organisms Gain Oxygen & Glucose?

Answer 2

Directly from their surroundings and the molecules can diffuse to all parts of the cell quickly due to a short diffusion distance.

Question 3

How Do Larger (Multicellular) Organisms Gain Oxygen & Glucose?
(4 Points)

Answer 3

~ They are made up of many layers of cells.

~ The time taken for substances to diffuse to every cell in the body would be too long.

~ Larger organisms have higher diffusion distances and energy requirements, this means the delivery of reactants for metabolism needs to happen quickly.

~ To solve this problem their exchange surfaces are connected to a mass transport system.

Question 4

Describe Mass Transport Systems
(2 Points)

Answer 4

~ Used to carry raw materials from specialised exchange organs to the body cells and to remove metabolic waste.

~ E.g. Circulatory system.

Question 5

What Do Mass Transport Systems Help To Do?
(3 Points)

Answer 5

~ Bring substances quickly from one exchange site to another.

~ Maintain diffusion gradients at exchange sites, between cells and their fluid surroundings.

~ Ensure effective cell activity by supplying reactants and removing waste products.