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
Q

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

A
  • 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
Q

Define ecosystem (2)

A
  • All the living organisms living in a particular area
  • And all the abiotic conditions, e.g climate, soil type
3
Q

Disadvantages of random sampling (2)

A
  • May not be representative of the population
  • Use a quadrat at several points and get an average value
4
Q

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

A
  • Eutrophication
5
Q

What happens when fertilisers leach into water (7)

A
  • 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
Q

Define habitat (1)

A
  • The place where an organism lives, e.g a field
7
Q

Define population (1)

A
  • All the organisms of one species in a habitat
8
Q

Define community (1)

A
  • All the different species in a habitat
9
Q

Define ecosystem (2)

A
  • All the organisms living in a particular area
  • And all the abiotic conditions, e.g temperature
10
Q

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

A
  • 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
Q

What would happen if lots of spiders died (3)

A
  • 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
Q

Describe the water cycle (5)

A
  • 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
Q

How is the carbon cycle affected by photosyenthesis (2)

A
  • Process ‘powered’ by photosyenthesis.
  • Green plants use carbon from carbon dioxide in the air to make carbohydrates, proteins and fats
14
Q

How does eating affect the carbon cycle (1)

A
  • Eating passes the carbon compounds in the plant along to animals in a food chain or web
15
Q

How does respiration affect the carbon cycle (2)

A
  • Plant and animal respiration while the organisms are alive
  • Releases carbon dioxide back into the air
16
Q

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

A
  • Die : they decompose and are broken down by bacteria and fungi
  • Killed : turned into useful products
17
Q

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

A
  • 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
Q

Two main examples of nitrogen fixation (3)

A
  • 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
Q

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

A

Nitrogen fixation

20
Q

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

A
  • 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
Q

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

A
  • 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
Q

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

A
  • CO mostly released in car emissions
  • Modern cars are fitted with catalytic converters, that turn carbon monoxide into carbon dioxide
23
Q

How does acid rain fall (4)

A
  • 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
Q

What is bad about acid rain (2)

A
  • 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
Q

What are the main causes of acid rain (2)

A
  • Internal combustion engines in cars
  • Power stations
26
Q
A
27
Q

Describe the greenhouse effect (9)

A
  • 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
Q

What things could climate change lead to (2)

A
  • Changing crop growth patterns
  • Flooding due to polar ice caps melting
29
Q
A
30
Q

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

A
  • Car exhausts
  • Industrial processes (burning fossil fuels)
  • Deforestation (less trees to take in carbon dioxide for photosyenthesis)
31
Q

How do humans release methane into the atmosphere (3)

A
  • Produced naturally e.g rotting plants in marshland
  • Man made sources on the increase
  • Rice growing and cattle rearing
32
Q

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

A
  • 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
Q

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

A
  • 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
Q

How does deforestation cause leaching (3)

A
  • 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
Q

How does deforestation disturb the water cycle (4)

A
  • 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
Q

How does deforestation cause soil erosion (3)

A
  • Tree roots hold the soil together
  • When trees are removed, soil can be eroded by rain
  • Leaving infertile ground
37
Q

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

A
  • 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