Distribution of Organisms

Question 1

What are biotic factors?

Answer 1

Factors in the ecosystem that are related to biological, living things

Question 2

What are abiotic factors?

Answer 2

Non-living factors within the ecosystem that can be measured

Question 3

What are some examples of biotic factors?

Answer 3

Predation, grazing, food availability, disease and competition for resources

Question 4

How can predation affect biodiversity?

Answer 4

Through predator-prey interactions

Question 5

What are some examples of abiotic factors?

Answer 5

Light intensity, moisture, temperature and pH

Question 6

How do you measure light intensity?

Answer 6

By using a light meter

Question 7

How do you measure temperature?

Answer 7

By using a thermometer

Question 8

How do you measure soil moisture?

Answer 8

By using a moisture meter

Question 9

How do you measure pH?

Answer 9

By using a soil pH meter

Question 10

What are the sources of error in measuring abiotic factors?

Answer 10

• getting the wrong temperature reading
• causing a shadow over the light meter
• getting the pH and moisture readings to all be the same

Question 11

What is the solution to getting the wrong temperature reading?

Answer 11

Give the thermometer time to reach the correct temperature

Question 12

What is the solution to causing a shadow over the light meter?

Answer 12

Do not shadow the light meter

Question 13

What is the solution to getting the pH and moisture to all be the same?

Answer 13

Clean and dry the probe before and after each use

Question 14

How could we measure plant population sizes in a field?

Answer 14

By using quadrats and transect lines

Question 15

What are quadrats used for?

Answer 15

To sample low growing plants (e.g. clover) by marking off an exact area of ground so that the organisms can be identified and counted

Question 16

How do you use a quadrat?

Answer 16

1. Throw the quadrat randomly
2. Count the number of each species in the quadrat
3. Record the results
4. Repeat several times to get an average

Question 17

Why would you throw the quadrat randomly?

Answer 17

To ensure the experiment is valid by eliminating any chance of bias by aiming for areas with lots of the species that you are measuring

Question 18

Why would you repeat the experiment?

Answer 18

To ensure that the results taken are reliable so that any result that may not be what is expected is realised

Question 19

What are the limitations of quadrats?

Answer 19

Quadrat Size and Species Sampled

Question 20

How could you measure the number of invertebrate species in a field?

Answer 20

By using pitfall traps

Question 21

What are pitfall traps used for?

Answer 21

To sample small invertebrate species living on the soil surface because species fall in and are unable to climb back out again, so they can be measured after a period of time

Question 22

How do you use a pitfall trap?

Answer 22

1. Dig a hole and place a cup in it so that the top of the cup is level with the ground
2. Make sure there are drainage holes at the bottom of the cup
3. Cover the top of the cup with leaves
4. Repeat 5 times
5. Leave for 24 hours
6. Identify the species in the cup

Question 23

Why are drainage holes put in the cup?

Answer 23

To allow water to drain out so that the invertebrate species are not harmed and that the cup doesn’t overflow with water

Question 24

Why must the cup be level with the ground?

Answer 24

So invertebrate species can fall in which means that the species identified at the end are a better representation of the species found in the sampling area