SA, metabolic rate, data and studies

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

lolwer 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

Question 8

What is a
- risk factor
- incidence
- prevalence

Answer 8

• Risk factor - Any factor that contributes to an increased risk of suffering from a condition or disease e.g. smoking is a risk factor
• Incidence- Describes the number of new cases of a disease or condition within a particular group of people in a time
• Prevalence - The total number of cases there are currently in the population

Question 9

How is data collected when investigating the effect of risk factors on the incidence of disease in humans

strengths and weaknesses

Answer 9

Prospective - Collecting data as it becomes available
+ more accurate data can be obtained
- highly time consuming
Retrospective - collecting data from the past
+ obtained easily
- could be outdated as new research evolves

Question 10

What is the relative risk (RR)

Answer 10

Measure to compare the risk in epidemiology of a certain event (e.g. developing a disease) occurring in two different groups. Often used to determined the strength of association
- 1 - equal in the exposed group and the unexposed group showing no association between exposure and outcome
- more than 1 - Risk is higher in exposed groups compared to unexposed groups showing a positive association
- less than one - Risk lower in exposed groups than unexposed showing a protective effect of the exposure