Section 8 - Ecology and the Environment Flashcards Preview

Edexcel GCSE Biology > Section 8 - Ecology and the Environment > Flashcards

Flashcards in Section 8 - Ecology and the Environment Deck (37)
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1

How do you estimate population sizes using a quadrat (4)

- Place a 1m^2 quadrant at a random point within the area you’re investigating

- Count all organisms within the quadrat

- Multiply no. organisms by the total area of the habitat

- Do it in another area and compare population sizes

2

Define ecosystem (2)

- All the living organisms living in a particular area

- And all the abiotic conditions, e.g climate, soil type

3

Disadvantages of random sampling (2)

- May not be representative of the population

- Use a quadrat at several points and get an average value

4

When fertilisers leach into water what effect does it cause (1)

- Eutrophication

5

What happens when fertilisers leach into water (7)

- Eutrophication

- Fertiliser leach into water, adding extra nutrients (nitrates and phosphates)

- Extra nutrients cause algae to grow at a faster rate and block out the light

- Plants can’t photosynthesise due to lack of light and start to die

- Microorganisms that feed on dead plants increase in number

- deplete all the oxygen in the water

- organisms that need oxygen e.g fish, die

6

Define habitat (1)

- The place where an organism lives, e.g a field

7

Define population (1)

- All the organisms of one species in a habitat

8

Define community (1)

 

- All the different species in a habitat

9

Define ecosystem (2)

- All the organisms living in a particular area

- And all the abiotic conditions, e.g temperature

10

How can you use quadrats to investigate the distribution of organisms (4)

- Lay quadrats along a line called a transect

- Mark out a line in the area you want to study

- Collect data along the line using quadrats

- Placed next to each other

11

What would happen if lots of spiders died (3)

- Less food for the frogs, numbers might decrease

- Water spiders wouldn't be eating Mayfly larvae, so numbers might increase

- Diving beatles wouldn't be competing with water spiders for food, numbers might increase

12

Describe the water cycle (5)

- Heat from the Sun makes water evaporate from the land and sea, turning it into water vapour

- Water also evaporates from plants, transpiration

- Warm water vapour is carried upwards as warm air rises

- When it gets higher it cools and condenses to form clouds

- Water falls from clouds as precipitation, returning to land and sea

13

How is the carbon cycle affected by photosyenthesis (2)

- Process 'powered' by photosyenthesis.

- Green plants use carbon from carbon dioxide in the air to make carbohydrates, proteins and fats

14

How does eating affect the carbon cycle (1)

- Eating passes the carbon compounds in the plant along to animals in a food chain or web

15

How does respiration affect the carbon cycle (2)

- Plant and animal respiration while the organisms are alive

- Releases carbon dioxide back into the air

 

16

When plants or animals die/are killed, how does this affect the carbon cycle (2)

- Die : they decompose and are broken down by bacteria and fungi

- Killed : turned into useful products

17

How do plants and animals decomposing/being killed affect the carbon cycle (4)

- Plants/animals decompose, broken down by bacteria and fungi

- These decomposers release carbon dioxide back into the air by respiration, as they break down the material

- Some useful plants/animal products, e.g wood, are combusted

- This releases carbon dioxide back into the air

18

Two main examples of nitrogen fixation (3)

- Lightning

- So much energy in one bolt of lightning, it's enough to make nitrogen react with oxygen in the air to give nitrates

- Nitrogen fixing bacteria in roots and soil

19

What is the process by which nitrogen from the air is turned into nitrogen compounds in the soill which plants can use (1)

Nitrogen fixation

20

Four types of bacteria involved in the nitrogen cycle (8)

- Decomposers (break down proteins in rotting plants/animals and urea in animal waste to form ammonia, a nitrogen compound)

- Nitrifying bacteria (turn ammonia in decaying matter into nitrates)

- Nitrogen fixing bacteria (turn atmopsheric nitrogen into nitrogen compounds plants can use)

- Denitrifying bacteria (turn nitrates back into nitogen gas, no benefits)

21

How is carbon monoxide produced and how is it harmful (2)

- When fossil fuels are burnt without enough air supply, produces carbon monoxide

- If it combines with red blood cells, it prevents them from carrying oxygen

22

How is CO most commonly released and how are humans trying to stop this (2)

- CO mostly released in car emissions

- Modern cars are fitted with catalytic converters, that turn carbon monoxide into carbon dioxide

23

How does acid rain fall (4)

- Burning fossil fuels releases sulfur dioxide

- Sulfur dioxide comes from sulfur impurities in fossil fuels

- Mixes with rain clouds to form sulfuric acid

- Falls as acid rain

24

What is bad about acid rain (2)

- Causes lakes to become more acidic : many organisms can’t survive in acidic conditions so die

- Kills trees : acid releases toxic substances from the soil, making it hard for the trees to take up nutrients

25

What are the main causes of acid rain (2)

- Internal combustion engines in cars

- Power stations

26

27

Describe the greenhouse effect (9)

- Temp of the earth is a balance between heat it gets from the Sun, and heat it radiates back into space

- Gases in the atmosphere absorb most of the heat that would normally be radiated into space

- Re-radiate it in all directions (inc back towards the Earth)

- Greenhouse gases are the ones that keep the heat in

- E.g water vapour, carbon dioxide and methane

- Humans increasing amount of carbon dioxide

- Increasing levels of CFC's and nitrou oxide

- Enhances greenhouse effect

- Causing global warming

28

What things could climate change lead to (2)

- Changing crop growth patterns 

- Flooding due to polar ice caps melting

29

30

How do humans release carbon dioxide into the atmosphere (3)

- Car exhausts

- Industrial processes (burning fossil fuels)

- Deforestation (less trees to take in carbon dioxide for photosyenthesis)

31

How do humans release methane into the atmosphere (3)

- Produced naturally e.g rotting plants in marshland

- Man made sources on the increase

- Rice growing and cattle rearing

32

How do humans release nitrous oxide into the atmosphere (3)

- Released naturally by bacteria in soils and the ocean

- A lot more is released from soils after fertiliser is used

- It's also released from vehicle engines and industry

33

What are CFC's and how are they releasing carbon dioxide into the atmosphere (3)

- Man mae chemicals in aerosol sprays and fridges

- Powerful greenhouse gases

- Most countries stopped producing them as they are damaging the ozone layer

- Some CFC's still remain and get releases, e.g by leaks in old fridges

34

How does deforestation cause leaching (3)

- Trees take up nutrients from the soil before they can be leached by rain

- and return them to soil when leaves die

- When trees are removed nutrients get leached, and don't get replaced, leaving infertile soil

35

How does deforestation disturb the water cycle (4)

- Trees stop rainwater reaching rivers too quickly

- When cut down, rainwater runs straight into rivers, leading to flooding

- Transpiration from trees releases some rainwater back into the atmosphere

- Can make the local climate drier

36

How does deforestation cause soil erosion (3)

- Tree roots hold the soil together

- When trees are removed, soil can be eroded by rain

- Leaving infertile ground

37

How does deforestation disturb the balance of carbon dioxide and oxygen (5)

- Forests take up carbon dioxide by photosyenthesis, store it in wood

- Slowly release it when they decompose (micro organisms respiring)

- When trees are cut down and burnt, stored carbon is released as carbon dioxide

- Contributing to global warming

- Fewer trees : fewer photosyenthesis : releases less oxygen : oxygen level in atmosphere drops