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Edexcel GCSE Biology > Topic 9- Ecosystems And Material Cycles > Flashcards

Topic 9- Ecosystems And Material Cycles Flashcards

1
Q

Ecosystem organisation levels

A

Individual
Population
Community
Ecosystem

I Particularly Can’t Eat

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2
Q

Individual

A

A single organism

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3
Q

Population

A

All the organisms of one species in a habitat

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4
Q

Community

A

All the organisms of different species living in a habitat

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5
Q

Ecosystem

A

A community of organisms along with all the non-living (abiotic) conditions.

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6
Q

Interdependence

A

Organisms depending on each other for things like food and shelter to survive and reproduce.

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7
Q

What impacts does interdependence have?

A

It means a change in population can have huge knock-on effects for other species in community.

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8
Q

Species

A

Group of similar organisms that can reproduce to give fertile offspring.

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9
Q

Mutualism

A

A relationship between 2 organisms from which both organisms benefit (eg bees and flowers)

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10
Q

How do bees and flowers have a mutualistic relationship.

A

Bees visit flowers to transfer pollen to their bodies which then is spread to other plants to help flowers reproduce while bees are fed.

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11
Q

Why don’t parasites and their hosts share a mutualistic relationship?

A

Because the plant takes what it needs to survive while the host doesn’t benefit.

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12
Q

What are changes in the environment caused by?

A

Abiotic (non-living) factors or biotic (living) factors

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13
Q

Abiotic factors

A

Temperature
Water amount
Light intensity
Pollutants levels

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14
Q

Biotic factors

A

Competition

Predation

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15
Q

How can you study the distribution of small organisms?

A

Using QUADRATS

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16
Q

Quadrat

A

A square frame enclosing a known area, eg 1 meter squared

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17
Q

How do you use quadrats

A
  1. ) place a quadrat on the ground at a RANDOM point within the first sample area.
  2. ) Count all organisms you are interested in that quadrat.
  3. Repeat a lot and work out mean
  4. Repeat these steps for 2nd sample area
  5. Compare 2 means
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18
Q

Why do you need a random point within the sample area?

A

So your results are representative of the sample area

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19
Q

How do you work out population size of an organism?

A

Work out the mean number of organisms per meter squared and multiply it by the total habitat area

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20
Q

Gradient

A

Changing abiotic factors across a habitat

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21
Q

How do you measure a belt transect?

A
  1. Mark out a line across the area you want to study
  2. Collect data along line using lined quadrats & counting plants of interest/estimating % area covered.
  3. Simultaneously you can also record abiotic factor data
  4. Repeat much and get mean. Form graph 2 see correlation
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22
Q

Source of energy for all life on earth

A

Sun

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23
Q

What do plants do w the sun’s light energy ?

A

Converts % of energy to glucose

Which is used for immediate respiration or stored in biomass

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24
Q

Biomass

A

Mass of the living material that makes up an organism

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25
Q

What happens when rabbit eats plant which is eaten by Fox?

A

Uses plant biomass energy and stores rest as biomass. Fox receives rabbit biomass energy .

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26
Q

Trophic level

A

Each stage of a food chain

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27
Q

What happens to the energy used by organisms

A

Used for life processes including movement and heat transfer to surroundings.

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28
Q

What happens to energy not stored as biomass?

A

It’s not transferred to the next trophic level and can be lost via heat or faeces.

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29
Q

What’s the general maximum number of trophic levels in a food chain?

A

5 as so much energy is lost at each stage so there isn’t enough energy to support past this.

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30
Q

What does a pyramid of biomass show?

A

How much creatures at each trophic level would weigh if you put them together, as well as how much energy there is at each trophic level.

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31
Q

Starting point of food chain

A

Producer (mostly plants eg dandelion)

Make energy from sun energy

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32
Q

What eats the producers?

A

Primary consumers

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33
Q

What eats the primary consumers?

A

Secondary consumers

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34
Q

What happens as you go up each trophic level?

A

Mass of organisms goes down as most biomass is lost

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35
Q

Unit of energy in food chains

A

kJ (kilojoules)

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36
Q

Efficiency of energy transferred formula

A

Energy transferred to next level /energy available at previous level*100

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37
Q

Biodiversity

A

The variety of living organisms in an ecosystem

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38
Q

What are used as fertilisers?

A

Nitrates

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39
Q

What’s eutrophication?

A

An excess of nutrients in water

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40
Q

What effect do the fertilisers have on algae? What does this mean?

A

Cause algae to grow fast and block out the light. Therefore plants can’t photosynthesise due to lack of light (die). Therefore organisms that eat dead plants increase and use up oxygen in the water so organisms relying on aerobic respiration die.

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41
Q

What has the same effect of eutrophication?

A

Pollution (sewage)

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42
Q

Problem w fish farms involving food

A
  1. Food is added to nets for fish (producing waste) which can leak into open water and so cause eutrophication / death of wildlife.
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43
Q

Problem w fish farms involving infection

A

Parasites can breed and so infect/kill wild animals

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44
Q

Problem w fish farms involving predators

A

Attracted to nets and become stuck / die

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45
Q

Problem w fish farms involving indigenous species

A

Farmed fish can escape into wild and affect numbers of indigenous species

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46
Q

What’s the better alternative to fish nets?

A

Being kept in tanks free of plants/predators/parasites/microorganisms

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47
Q

Non-indigenous species

A

A species that doesn’t naturally occur in the area.

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48
Q

How do non-indigenous species affect biodiversity?

A

They compete w other indigenous species for resources (food/shelter), can outcompete the indigenous species meaning they decrease in number and so die out.
Can also bring new diseases which infects and kill lots of indigenous species reducing biodiversity.

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49
Q

Reforestation

A

When land where a forest previously stood is replanted to form a New Forest

50
Q

Why do forests generally have a high biodiversity?

A

As they contain a wide variety of trees/plants which mean food and shelter for different species

51
Q

What do conservation methods include?

A

Protecting natural habitats
Protecting safe areas outside habitats and introducing captive breeding programs to increase numbers
Seed banks to store/distribute seeds of rare/endangered plants

52
Q

What are the benefits of maintaining biodiversity?

A 
Protects human food supply
insures minimal damage to food chains 
provide future medicine
 culture aspects
Eco-tourism
Jobs
53
Q

How Will maintaining biodiversity protect human food supply?

A

Prevent exploitation of animal species so that future generations may have food to eat
Eg fishing

54
Q

How does maintaining biodiversity insure minimal damage to food chains?

A

By conserving one species this may mean that others can survive as they live off of that species.
Eg maintaining rabbit numbers mean foxes will have food to eat

55
Q

How old maintaining biodiversity provide future medicines?

A

Undiscovered species of plants may become extinct which could’ve been used for new medicinal chemicals

56
Q

How does maintaining biodiversity link to cultural aspects?

A

As individual species may be important to a nation or areas cultural heritage. Eg: the bold eagle in America

57
Q

How does maintaining biodiversity help eco-tourism?

A

As tourists want to see unspoiled landscapes with varieties of species, money is brought into biodiverse areas where conservation work is taking place.

58
Q

How does maintaining biodiversity provide new jobs?

A

Things like eco tourism and conservation schemes can provide employment opportunities for local people

59
Q

Food security

A

As the world’s population continues to grow we need to produce more food, so that each person still has the same amount of food to eat.

60
Q

Factors affecting food security

A

Increasing human population
Increasing consumption of meat/fish increasing animal farming
Environmental changes caused by human activity
Sustainability
New pests and pathogens

61
Q

How does increasing consumption of meat/fish affect food security?

A

Wealthier= larger variety of foods&raquo_space; expensive fish and meat
Much more energy by growing crops as is lower down in trophic level and animals will be fed crops meant for humans
Risk of overfishing fish

62
Q

How are man-made environmental changes affecting food security?

A

Fossil fuel combustion releases greenhouse gases (like CO2) causing global warming which changes rainfall patterns, affecting crop growth, reducing yield. Soil pollution also affects this.

63
Q

Yield

A

Amount of useful products made

64
Q

How does sustainability affect food security?

A

Biofuels are renewable alternatives to fossil fuels but take up crop land. Need to balance need for biofuels w need for food now and in future.
Also, high farming input costs mean farmers can’t maintain food production.

65
Q

Sustainability

A

Meeting needs of today’s population without affecting the ability of future generations to meet their needs.

66
Q

How are new pests and pathogens affecting food security?

A

Pests/pathogens can damage crops and livestock, reducing yield

67
Q

What are living things made out of?

A

Elements they take from the environment

Eg plants take in carbon/oxygen from air and nitrogen from soil

68
Q

What breaks down waste products and dead organisms?

What do they do with them?

A

Decomposers then release the elements to the soil/air

69
Q

What takes in carbon dioxide in the carbon cycle ?

A

Photosynthesising plants, using carbon from CO2 to make carbohydrates, fats and proteins

70
Q

What does eating do in the carbon cycle?

A

Passescarbon compounds in plants down animals in food chain.

71
Q

How is CO2 released into the air?

A

Respiration of plants/animals/microorganisms
Decay (decomposers respire too) meaning habitats can be maintained
Combustion

72
Q

Transpiration

A

The evaporation of water from plants

73
Q

What effect does the sun have on the water cycle?

A

Makes water evaporate from the land and sea into water vapour.

74
Q

How are clouds formed?

A

Warm water vapour is carried upwards before cooling and condensing

75
Q

What does precipitation do?

A

It provides fresh water for plants and animals which then drains into sea before whole process starts again.

76
Q

4 stages of water cycle

A

Evaporation
Condensation / transpiration
Precipitation

77
Q

Desalination

A

The removal of salts (mineral ions) from salt water (eg sea).

78
Q

Thermal desalination

A

Where salt water is boiled in a large, enclosed vessel causing water to evaporate. Salt stays at bottom while steam rises and travels separately to condense.

79
Q

Osmosis

A

The passive, net movement of water molecules from an area of high concentration to low concentration, down the concentration gradient ACROSS A PARTIALLY PERMEABLE MEMBRANE.
Can also be low salt concentration to high salt concentration

80
Q

Reverse osmosis

A

Salt water (treated for solids) is fed at high pressure into a vessel w a partially permeable membrane.
Pressure causes molecules to move opposite to osmosis (high to low salt concentration)
As water is forced through the membrane, salts are left behind, removing them from the water.

81
Q

% nitrogen in atmosphere

A

78%

82
Q

Nitrogen symbol

A

N2

83
Q

Properties of nitrogen

A

Unreactive (can’t be used directly by plants/animals)

84
Q

What is nitrogen needed for?

A

Making proteins for growth (in living organisms)

85
Q

How do plants use nitrogen?

A

Nitrates (mineral ions) can be absorbed from soil by plants and so passed along food chain in form of proteins

86
Q

Function of decomposers

A

(Bacteria/fungi in soil) breaks down proteins in rotting plants/animals as well as urea (in waste).
Therefore nitrogen is returned to soil, recycling nitrogen.

87
Q

Nitrogen fixation

A

Process of turning N2 from air into nitrogen containing ions in soil to be used by plants.

88
Q

2 methods of nitrogen fixation

A

Lightning - energy causes nitrogen to react w oxygen in air to produce nitrates.
Nitrogen fixing bacteria in roots/soil

89
Q

4 different types of bacteria involved in the nitrogen cycle

A

DECOMPOSERS
NITRIFYING BACTERIA
NITROGEN FIXING BACTERIA
DENITRIFYING BACTERIA

90
Q

Decomposers

A

Decompose proteins and urea into ammonia, forming ammonium ions in solution to be used by plants.

91
Q

Nitrifying bacteria

A

Turns ammonia into nitrites then nitrates

92
Q

Nitrogen fixing bacteria

A

Turns nitrogen in air into ammonia/ ammonium ions

93
Q

Denitrifying bacteria

A

Turns nitrates back into nitrogen gas.

94
Q

Where’s denitrifying bacteria often found?

A

Waterlogged soils

95
Q

Where are nitrogen fixing bacteria usually found?

A

Soil/ nodules on roots of legume plants.

96
Q

What happens when legume plants containing nitrogen fixing bacteria decompose?

A

Nitrogen stored is returned to soil or has already leaked out during plant growth.

97
Q

Relationship between plants and nitrogen fixing bacteria?

A

MUTUALISTIC

Bacteria is fed (sugars) while plants receive nitrogen ions to make proteins

98
Q

Why is nitrogen not returned to the soil in crop fields?

A

Because plants are harvested, not decomposing so nitrogen isn’t returned to the soil.
Gradually soil nitrogen content decreases

99
Q

What happens when soil has low nitrogen content?

A

There’s poor crop growth and deficiency diseases.

100
Q

How can farmers increase nitrogen content in the soil?

A

CROP ROTATION

FERTILISERS

101
Q

What’s crop rotation

A

Where different crops are grown each year in a cycle, including a nitrogen fixing crop such as peas/beans.

102
Q

How do fertilisers work?

A

Animal manure/compost recycles plant nutrients back to soil via decomposition. Artificial nitrogen containing fertilisers are v expensive

103
Q

Indicator species

A

Organisms that are v sensitive to changes in their environment so can be studied to see effects of human activities.

104
Q

What happens if raw sewage or nitrate fertilisers are released into the river?

A

Microorganisms in water increase in number so use up oxygen.

105
Q

Why are some invertebrate animals good indicators for water pollution?

A

Because they are v sensitive to concentration of dissolved oxygen in water and so whether the water is clean.

106
Q

How can air pollution be monitored?

A

By looking at types of lichen which are sensitive to sulfur dioxide (pollutant released by car exhausts)
Number/type of lichen shows how clean air is.

107
Q

Quick way of telling whether an area is polluted or not

A

A simple survey to see if a species is present/absent from an area
*cant tell how polluted an area is

108
Q

Test to see how polluted an area is

A

Number of times an indicator species occurs in an area allowing you to compare

109
Q

Positives and negatives of using indicator species

A

Cost effective and simple

Can’t give accurate figures/ other factors affecting presence of species

110
Q

How do you measure changing water pollution?

A

Dissolved oxygen meters/chemical tests

111
Q

How do you accurately measure changing air pollution levels?

A

Electronic meters/lab tests measure sulfure dioxide in air

112
Q

Black spot fungus indication?

A

Clean air as is sensitive to sulfur dioxide in air

113
Q

What happens when living things die or release waste?

A

Decomposition returns waste back to soil/air

114
Q

What does rate of decay depend on?

A

Temperature
Water content
Oxygen availability

115
Q

How does temperature affect decomposition?

A

Warm temp speeds up rate of enzyme controlled reactions in microbes / decay.
Although too high temp denatures enzymes

116
Q

How does water content affect decay?

A

Takes place faster in moist environments as organisms need water for life processes

117
Q

How does oxygen availability affect rate of decomposition?

A

Faster w more oxygen as organisms need to aerobically respire

118
Q

How do you reduce rate of decay?

A

Put in fridge/freezer to slow down rate of reproduction
Storing in airtight containers (cans) - high pressure and temp sterilises and prevents decay
Drying food / adding salt or sugar - removes necessary water or causes microorganisms to lose water via osmosis

119
Q

Compost

A

Decomposed organic matter used as fertiliser for crops/gardens.

120
Q

When’s compost produced quickest?

A

In warm, moist conditions w loads of oxygen.

Why mesh is used in sides of compost bins / is insulated

121
Q

How do you measure rate of decomposition?

A

Divide amount of mould by number of days

Edexcel GCSE Biology (12 decks)

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