Topic 5A: Investigating populations and abiotic factors

Question 1

What are the two factors when investigating populations of organisms?

Answer 1

Abundance and distribution

Question 2

Why do people use samples for investigation in Biology?

Answer 2

Too time-consuming to use every individual

Question 3

What does sampling involve in biology? (4)

Answer 3

– Choosing area to sample

– Counting number of individuals in each species

– Repeat process– Get many samples

– Use results to estimate total number of individuals

Question 4

Why should you take as many samples as possible?

Answer 4

Gives more representative sample of the whole habitat

Question 5

When sampling different habitats and comparing them, what should you do to the sampling techniques?

Answer 5

Use the same sampling technique

Question 6

In biology why do scientists use a random sample?

Answer 6

To avoid bias

Question 7

In biology when is it necessary to use a non-random sample?

Answer 7

• In habitats where there are lots of variety in the abiotic factors and/or distribution of species

– To make sure all the different areas or species are sampled

Question 8

Give an example of a type of non-random sampling and explain what it is (2)

Answer 8

-Systematic sampling

– Samples are taken at fixed intervals along line

Question 9

When is it good to you systematic sampling?

Answer 9

– When abiotic factors in a habitat change gradually (environmental gradient)

Question 10

When should you use frame quadrat?

Answer 10

To investigate immobile populations

Question 11

Explain how a frame quadrat can be used

Answer 11

– Randomly choose a range of coordinates

– Place quadrat in area you’re investigating

– Count number of individuals of each species in the quadrat

Question 12

From a frame quadrat how do you work out percentage cover of a plant species?

Answer 12

– Count to square if it’s more than half covered

– Divide number by the no of squares them times 100

Question 13

How do you workout mean density?

Answer 13

Total number of individuals/total area

Question 14

What are frame quadrat is useful for?

Answer 14

Quickly investigating areas with species that fit within a small quadrat

Question 15

What can point quadrat to be used for?

Answer 15

To investigate plant populations

Question 16

Describe how you would use a point quadrat (4)

Answer 16

– Place point quadrat on the ground at random point

– Dropping through each hole in the frame

– Record every plant that each pin touches

– Record number of individuals of species in each quadrat

Question 17

Using a point quadrat how would you work out percentage cover?

Answer 17

(Number of pins that touch given species/total number of pins dropped) X100

Question 18

What are transects used for?

Answer 18

To investigate distribution of plant populations across and area

Question 19

What are the three types of transects?

Answer 19

– Line transects

– Belt transect

– Interrupted transects

Question 20

Give examples of abiotic factors you can measure with in a habitat

Answer 20

– Climate

– Oxygen availability

–Solar input

– Edaphic factors

– Topography )shape and features of earth

Question 21

What apparatus would you use to measure the following climate factors:

– Temperature

– Rain for

– Humidity

Answer 21

– Thermometer

– Rain gauge : Final attached to a measuring cylinder collect water and measure volume over a period of time

– Hygrometer: measures amount of water vapour in air

Question 22

What apparatus would you use to measure oxygen availability?(2)

Answer 22

– Oxygen sensor

– Measures amount of dissolved oxygen

Question 23

What are the two ways of measuring edaphic factors?

Answer 23

– PH using a pH monitor

– Moisture content by measuring mass of sample before and after being dried out