SA and metabolic rate

Question 1

What is surface area important in and what is the surface are volume of an object

Answer 1

Important in exchange of materials in organisms
Surface area - total area of the organism that is exposed to the external environment
Volume - Total internal volume of the organism (total space inside)

Question 2

What happens when surface area and volume increases and why

Answer 2

Surface area : Volume ratio decreases
Because the the volume increases more rapidly than surface area as size increases

Question 3

How do you work out the surface area to volume ratio of a
cube
cuboid
cylinder

Answer 3

Make all volume in ratio 1 by dividing everything in ratio by the volume
Cube
SA = (B x H) of one face then (X6)
V = B x W x H
Cuboid
SA = (B x h) long face (x4)
(B x h ) short face x 2
Add
V = B x H x W
Cylinder
circle = πr²h
rectangle = 2πrh
SA= 2πrh + 2πr²
V = πr²h

Question 4

What is the investigation into surface area with agar

Answer 4

• Cut coloured agar into cubes of required dimensions (0.5,1,1.5)
• Calculate SA, Volume and SA:V ratio of each cube
• Place agar cubes into boiling tubes containing diffusion solution (hydrochloric acid)
• Measure time taken for cubes agar cubes to become colourless

Question 5

What is the relationship between SA:V ratio and metabolic rate

Answer 5

Larger SA:V ratio the larger the metabolic rate
meaning a greater demand for oxygen

Question 6

How does the relationship between SA:V ratio and metabolic rate effect larger organisms

Answer 6

They have a lower SA:V so it is harder to get the oxygen needed so they have to have adaptations

Question 7

What are the 3 things you need successful gas exchange

Answer 7

Large surface area
short diffusion distance
concentration gradient