Unit 3.2: Distribution of organisms

Question 1

Describe what a biotic factors.

Answer 1

Factors that effect living organisms

Question 2

Give examples of biotic factors.

Answer 2

Predation
Disease
Food competition
Space competition
Grazing

Question 3

Describe the effect of the lack of predation on prey populations.

Answer 3

Removing predators increases preys population

Question 4

Describe the effect of increased predation on prey populations.

Answer 4

If there’s more predators prey would decreases

Question 5

What happens in low levels of grazing?

Answer 5

Biodiversity decreases because fast-growing vigorous plants will grow and block out light from smaller, low growing plants which stop them from photosynthesising.

Question 6

What happens in high levels of grazing?

Answer 6

Biodiversity increases because it keeps fats growing vigorous plants in check so all plants get light and photosynthesis

Question 7

What happens in very high levels of grazing?

Answer 7

Biodiversity decreases because all plants except low ones get eaten

Question 8

Describe what an abiotic factor is.

Answer 8

Factors that effect non-living organisms

Question 9

Give examples of abiotic factors.

Answer 9

pH
Temperature
Moisture
Light intensity

Question 10

Why does increasing light intensity increases plant growth?

Answer 10

The more light there is available the more plants photosynthesis and thus thrive

Question 11

Why do low levels of water decrease plant growth?

Answer 11

There is not enough water for the plants to thrive and stay healthy so that tends to make them die

Question 12

How do you measure light intensity?

Answer 12

Using a light meter

Question 13

What errors can happen with using a light meter and how do you reduce it?

Answer 13

You can end up blocking the sensor so ensure the sensor is facing towards the light

Question 14

How do you measure soil moisture?

Answer 14

Using a moisture meter

Question 15

What errors can happen with using a moisture meter and how do you reduce it?

Answer 15

If the probe is dirty so after every use make sure to clean the probe

Question 16

How do you measure pH?

Answer 16

By using a pH meter

Question 17

What errors can happen with using a pH meter and how do you reduce it?

Answer 17

If the probe is dirty so after every use clean it

Question 18

How do you measure temperature?

Answer 18

By using a thermometer

Question 19

What errors can happen with using a thermometer and how do you reduce it?

Answer 19

By using a dirty thermometer or reading it immediately after placing it so clean it after every use and let it sit for a while before taking measurements

Question 20

When measuring abiotic factors what is required to ensure a representative sample is taken?

Answer 20

By repeating it many times

Question 21

What are quadrats used to measure the abundance of?

Answer 21

Plants and slow living organisms

Question 22

How do you sample plant abundance using a quadrat?

Answer 22

Place randomly and count the number of squares not number of organisms

Question 23

What errors can occur in quadrat sampling?

Answer 23

Not placing randomly
Bad counting
Lack of knowledge with species

Question 24

Describe the step required in quadrat sampling to ensure representative sample is taken.

Answer 24

If more than half is in the quadrat then it counts

Question 25

State the type of organisms that pitfall traps are used to measure the abundance of.

Answer 25

Ground living invertebrates

Question 26

Describe how to sample using a pitfall trap.

Answer 26

Level with soil
Put drainage holes
Cover with leaves

Question 27

describe sources of error in pitfall traps.

Answer 27

Not levelling the pot with the ground so invertebrates dont fall
Birds taking the insects before they are counted
Leaving the trap for too long so predation of some organisms by other invertebrates.

Question 28

Describe the step required in pitfall traps to ensure a representative sample is taken.

Answer 28

Repeat with other pots for representative samples.

Question 29

State 5 human influences that result in a decrease in biodiversity.

Answer 29

Air pollution
Water pollution 
Habitat destruction
Desertification 
Over-fishing

Question 30

How does air pollution affect biodiversity?

Answer 30

the production of gases such as CO2, SO2 and nitrous oxide in high concentrations can kill many species

Question 31

How does water pollution affect biodiversity?

Answer 31

The release of sewage into waterways or oils spills at sea are the main causes. Oil destroys the insulating ability of fur-bearing animals and how well birds feathers repel water. Without that birds and mammals die from hypothermia. Plus raw sewage reduces oxygen levels killing many species.

Question 32

How does habitat destruction affect biodiversity?

Answer 32

Clearing space for roads, cities or agriculture many species living in these areas lose their habitats.

Question 33

How does desertification affect biodiversity?

Answer 33

Fertile land becomes desert, resulting in drought. many species cannot adapt to living in desert conditions so quickly so they die

Question 34

How does overfishing affect biodiversity?

Answer 34

Fish stocks become reduced to below acceptable levels resulting in resource depletion which reduces biological growth rates.

Question 35

Define endangered.

Answer 35

Certain species are at risk of becoming extinct

Question 36

Define indicator species.

Answer 36

If species are present or absent in an environment it indicates the quantity levels of pollution

Question 37

What are lichens used to indicate?

Answer 37

Air pollution

Question 38

How can mayfly larvae be used as an indicator?

Answer 38

They cannot survive in polluted areas so their absence means that there is pollution in that area.