investigating variation

Question 1

What does sampling allow?

Answer 1

To collect date which is representative of the community as a whole

Question 2

How may organisms be distributed?

Answer 2

Random, regular, clumped

Question 3

Why is random sampling effective?

Answer 3

-prevents researcher bias

Question 4

How would u carry out random sampling?

Answer 4

• lay out a grid
• use a random number generator on a calculator to provide co ordinates for the grid,
• place the right corner of the quadrat on the co orinate
• count the number of species in each quadrat
• a large number of randomly placed quadrats are used

Question 5

How many quadrats are needed to give a representative sample?

Answer 5

20

Question 6

How does agriculture provide ideal conditions for crop photosynthesis and growth?

Answer 6

• Selection of most appropriate crop species
• Fertilisers added to soil to provide mineral ions for growth
• Fields irrigated so enough water for crops

Question 7

Describe monoculture

Answer 7

Growth of one crop species

Question 8

How are weeds and pest species removed ?

Answer 8

• Use herbicides
• Use pesticides
• Ploughing

Question 9

Describe ploughing

Answer 9

Physically uproots weeds causing them to die

Question 10

Describe the mean

Answer 10

An average

Measure of central tendency

Question 11

What is standard deviation?

Answer 11

A measure of spread of values about the mean and indicated the extent of variation

Question 12

What does it mean is standard deviations overlap ?

Answer 12

There is no significant difference

Question 13

When is there a significant difference?

Answer 13

When standard deviations overlap

Question 14

What does it mean when standard deviations don’t overlap ?

Answer 14

There is a significant difference

Question 15

When is there no significant difference?

Answer 15

When standard deviations do not overlap

Question 16

Give techniques that can be applied to increases species and habitat diversity?

Answer 16

• maintain headrows
• plant hedges rather than fences
• maintain ponds
• don’t drain fields
• plant native trees
• use organic fertilisers
• use crop rotation
• create natural meadows
• leave the cutting verges
• introduce conservation headlands

Question 17

How can we ensure a sample is representative?

Answer 17

Random sampling

Ensures every member of the population has an equal chance of being included