2. Ecology Pt5

Question 1

What’s one way to measure the distribution & abundance of a species?

Answer 1

• using a quadrat

- which is a square to mark out the sample area in which the organisms can be counted

Question 2

When is quantitive sampling used?

Answer 2

When you want to compare the distribution of organisms in 2 different areas we use a method of random sampling

Question 3

Explain quantitive sampling in 6 steps

Answer 3

1. A grid is created over the first area, using tape measures the form X & Y axis like a graph
2. A random number generator produces a coordinate to lay the quarante on
3. The abundance of organisms is counted
4. This is repeated to give at least 10 readings
5. A mean is calculated
6. The procedure is repeated in the second area & the result compared in a bar chat (area type is a categoric variable)

Question 4

Why must the sample positions in quantitive sampling be random?

Answer 4

To remove any bias & ensure that the conclusions are valid

Question 5

Why must you take at at least 10readings in quantitate sampling?

Answer 5

To ensure the results are reliable (repeatable)

Question 6

What is transect sampling?

Answer 6

It’s a strip of land selected to see a change in distribution across an area

Question 7

Explain the process of transect sampling in 4 steps

Answer 7

1. Place a tape measure across the areas to study to mark out the transect
2. At regular intervals of et. 1m to produce at least 10 readings place a quadrat on the floor
3. Estimate the abundance of the species in the quadrat
4. Repeat the experiment at each distance & calculate a mean for each

Question 8

If both variable are continuous what type of graph do you draw?

Answer 8

A line graph

Question 9

What axis does the dependant variable go on?

Answer 9

Y axis

Question 10

What axis does the independent variable go on?

Answer 10

X axis

Question 11

What do you need to do when calculate the mean?

Answer 11

Discard anomalous results

Question 12

What 5 things do you consider when analysing a method?

Answer 12

• repeatability
• reproducibility
• validity
• accuracy
• precision

Question 13

Why is repeatability important when analysing a method?

Answer 13

• it indicates whether, if you did the experiment again what are the chances you’ll get the same results
• the best way to improve it is to take more readings & calculate the mean

Question 14

Why is reproducibility important when analysing a method?

Answer 14

• it indicates whether if someone else where to repeat the investigation, how likely would they be to obtain the same results
• obtaining more data allows you to identify anomalous results

Question 15

Why is validity important when analysing a method?

Answer 15

• it’s the suitability of the investigation procedure
• it’s a judgement of whether the method used gives a true representation of the suitable being studied
• it will be a combination of how well the variables were controlled & whether the sampling system was adequate, avoiding bias

Question 16

Why is accuracy important when analysing a method?

Answer 16

• it’s a measure of how close it is to the theoretical ‘true’ answer
• it’s determined by examining the method & identifying what errors may have taken place due to limitations in the procedure
• human or systematic
• the fewer the errors the greater the accuracy

Question 17

What’s precision?

Answer 17

Shows the spread of data around the mean