Unit 3.2: Distribution of organisms Flashcards Preview

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Flashcards in Unit 3.2: Distribution of organisms Deck (38)
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1
Q

Describe what a biotic factors.

A

Factors that effect living organisms

2
Q

Give examples of biotic factors.

A
Predation
Disease
Food competition
Space competition
Grazing
3
Q

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

A

Removing predators increases preys population

4
Q

Describe the effect of increased predation on prey populations.

A

If there’s more predators prey would decreases

5
Q

What happens in low levels of grazing?

A

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

6
Q

What happens in high levels of grazing?

A

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

7
Q

What happens in very high levels of grazing?

A

Biodiversity decreases because all plants except low ones get eaten

8
Q

Describe what an abiotic factor is.

A

Factors that effect non-living organisms

9
Q

Give examples of abiotic factors.

A

pH
Temperature
Moisture
Light intensity

10
Q

Why does increasing light intensity increases plant growth?

A

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

11
Q

Why do low levels of water decrease plant growth?

A

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

12
Q

How do you measure light intensity?

A

Using a light meter

13
Q

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

A

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

14
Q

How do you measure soil moisture?

A

Using a moisture meter

15
Q

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

A

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

16
Q

How do you measure pH?

A

By using a pH meter

17
Q

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

A

If the probe is dirty so after every use clean it

18
Q

How do you measure temperature?

A

By using a thermometer

19
Q

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

A

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

20
Q

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

A

By repeating it many times

21
Q

What are quadrats used to measure the abundance of?

A

Plants and slow living organisms

22
Q

How do you sample plant abundance using a quadrat?

A

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

23
Q

What errors can occur in quadrat sampling?

A

Not placing randomly
Bad counting
Lack of knowledge with species

24
Q

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

A

If more than half is in the quadrat then it counts

25
Q

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

A

Ground living invertebrates

26
Q

Describe how to sample using a pitfall trap.

A

Level with soil
Put drainage holes
Cover with leaves

27
Q

describe sources of error in pitfall traps.

A

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.

28
Q

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

A

Repeat with other pots for representative samples.

29
Q

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

A
Air pollution
Water pollution 
Habitat destruction
Desertification 
Over-fishing
30
Q

How does air pollution affect biodiversity?

A

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

31
Q

How does water pollution affect biodiversity?

A

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.

32
Q

How does habitat destruction affect biodiversity?

A

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

33
Q

How does desertification affect biodiversity?

A

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

34
Q

How does overfishing affect biodiversity?

A

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

35
Q

Define endangered.

A

Certain species are at risk of becoming extinct

36
Q

Define indicator species.

A

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

37
Q

What are lichens used to indicate?

A

Air pollution

38
Q

How can mayfly larvae be used as an indicator?

A

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