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AQA GCSE Biology (9-1) > 7. Ecology > Flashcards

7. Ecology Flashcards

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1
Q

What is a habitat?

A

The place where an organism lives

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2
Q

Examples of habitats?

A
  • woodland
  • grassland
  • icecap
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3
Q

What is a population?

A

All the organisms of one species living in a habitat

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4
Q

Examples of populations?

A
  • cattails

* wasps

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5
Q

What is a community?

A

The populations of different species living in a habitat

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6
Q

Example of a community?

A

all organisms within a pond

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7
Q

What are biotic factors?

A

Living factors which can affect s community and therefore the distribution of organisms

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8
Q

Examples of biotic factors?

A
  • new predators arriving
  • availability of food
  • new pathogens
  • competition between species
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9
Q

What are abiotic factors?

A

Non-living factors which can affect a community

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10
Q

Examples of abiotic factors?

A
  • moisture levels
  • light intensity
  • temperature
  • CO2 levels for plants
  • wind intensity and direction
  • O2 levels (aquatic)
  • soil pH and mineral content
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11
Q

What is an ecosystem?

A

The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment

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12
Q

Examples of ecosystems?

A
  • rainforest
  • arctic
  • aquatic
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13
Q

What is the interdependence?

A

When organisms are dependant on other organism within their community to survive and reproduce

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14
Q

What might organisms depend on others for?

A
  • food
  • shelter
  • pollination
  • seed dispersal
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15
Q

What is a stable community?

A

One where all the species and environmental factors are in balance so the population remains fairly constant

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16
Q

How is the population of yarrow estimated?

A

size = total area / area of quadrat x mean number of yarrow per quadrat

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17
Q

How does eutrophication occur?

A
  1. Fertiliser released in pond
  2. Algae multiply rapidly
  3. Algae below surface can’t get light to photosynthesise
  4. Algae die
  5. Bacteria cause decay of algae
  6. Bacteria multiply - respiration causes decrease in CO2 and fewer algae photosynthesising
  7. Fish/organisms die
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18
Q

What do field studies enable us to do?

A

Look at the distribution of organisms and the effects of environmental factors on this distribution

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19
Q

Where do venus fly traps thrive?

A

Where nitrate ions are very low, because they can live in areas of boggy soil where nitrate ions are low and instead get their nitrate from their insect victims

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20
Q

What are the sampling techniques used in field studies?

A
  • random sampling - using quadrats, in areas where distribution is quite uniform
  • systematic sampling - using transects, used to observe changes in distribution across areas of the habitat
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21
Q

What type of sampling are quadrats used in?

A

Random sampling

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22
Q

What type of sampling are transects used in?

A

Systematic sampling

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23
Q

Where are quadrats used?

A

In places where distribution is quite uniform

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24
Q

Where are transects used?

A

To observe changes in distribution across areas of the habitat

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25
Q

How could you measure how common an organism is in 2 or more sample areas?

A

Using quadrats, and comparing them

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26
Q

How could you study the distribution across an area?

A

By placing quadrats along a line known as a transect

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27
Q

What is random sampling?

A

A way of estimating - it should be logical, without bias to get an accurate reading that is representative of the area

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28
Q

What is the most common type of transect used?

A

A line transect

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29
Q

What do plants and animals compete for?

A

Light, space, minerals from soil (plants), food, mates and territory (animals)

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30
Q

What are the types of adaptation?

A
  • structural
  • behavioural
  • functional
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31
Q

What is structural adaptation?

A

Features of an organism’s body structure

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32
Q

What is behavioural adaptation?

A

The way an organism behaves

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33
Q

What is functional adaptation?

A

Processes within the organism

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34
Q

Examples of structural adaptation?

A
  • fur colour

* blubber

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35
Q

Examples of behavioural adaptation?

A
  • huddling
  • migration
  • display
  • avoiding the sun
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36
Q

Examples of functional adaptation?

A
  • hibernating lowers metabolism which conserves energy

* conserving water by producing very little sweat

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37
Q

What are the adaptations of a zebra?

A
  • live in herds so it’s hard for predators to detect them

* run at speed of slowest member

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38
Q

What are the adaptations of a penguin?

A
  • wings like flippers to help them swim
  • spikes in mouth help swallow live prey
  • huddle to keep warm while keeping eggs warm
  • swap place so none are on the outside the whole time
  • streamlined body helps catch prey and escape predators
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39
Q

What are the adaptations of a fennec fox?

A

• nocturnal to prevent dehydration

  • big ears to hear predators and lose heat
  • furry soles to stop feet burning on sand
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40
Q

What are the adaptations of dragonflies?

A
  • fly fast to avoid predators
  • female eggs have gel like substance to help stick to rocks
  • most of weight is muscle for strong flying
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41
Q

What are the adaptations of great white sharks?

A
  • rolls eyes back in socket at last minute before attack to protect self
  • grow back teeth that fall out whilst making an attack
  • streamlined for speed
  • can detect drop of blood several in away by receptors in nose
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42
Q

Why do some birds like swallows migrate?

A

To move from areas of low resources to areas of high resources

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43
Q

Why do penguins huddle?

A

To conserve heat and shelter themselves from intense winds - decreases SA so less heat is lost

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44
Q

Why penguins have a streamlined shape?

A

Allows them to swim fast in order to catch prey and escape predators and travel long distances

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45
Q

Why do camels store fat in their humps?

A

Minimises heat trapping insulation throughout rest of body and get water and energy from respiration

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46
Q

What do camels produce little urine and sweat?

A

To conserve water

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47
Q

Why do cacti have spines instead of leaves?

A

To minimise SA to reduce water loss and defence against predators

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48
Q

Why do some desert plants have widespread roots?

A

To collect water from a larger areas, during rainy seasons

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49
Q

Why do mesquite trees have deep vertical tap roots?

A

To absorb water from deep down in the soil

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50
Q

Why do arctic foxes have a thick coat?

A

To maintain a consistent body temperature because it is insulating and traps warm air

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51
Q

Why do arctic foxes have a white coat?

A

Winter camouflage to hide from predators

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52
Q

Why do arctic foxes have small ears?

A

To prevent heat loss by minimising SA exposed to cold air

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53
Q

Why do arctic foxes have front facing eyes?

A

To catch prey and to sense distance and depth

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54
Q

Why do walruses have a small surface area to volume ratio?

A

To lose less heat to the surroundings

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55
Q

Why do walruses have a thick layer of blubber?

A

To insulate and help keep them warm in icy water

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56
Q

Why does the coral snake have a highly venomous bite?

A

To kill and paralyse prey

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57
Q

Why does the coral snake have red/yellow/black colouration?

A

Warning colouration

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58
Q

What are extremophiles?

A

Organisms adapted to live in extreme conditions

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59
Q

What extreme conditions do certain extremophiles live in?

A

extreme:

  • temperatures
  • salinity
  • pH
  • pressure
  • nutrients
  • O2 levels
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60
Q

What do some micro organisms have that allow them to survive hot volcanic vents, hot springs etc?

A

They have thermostable enzymes which don’t denature at high temperatures

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61
Q

Features of ice fish?

A
  • found in Antarctica

* have no haemoglobin but enlarged heart and large blood vessels

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62
Q

Features of water bears?

A

• survive long periods of desiccation

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63
Q

Where do many tardigrades live?

A

In water

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64
Q

Where do you find tardigrades on land?

A

Where there’s moss or lichen

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65
Q

What is the process of one organism feeding on another?

A

The food chain

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66
Q

What is cycling?

A

Where materials are recycled

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67
Q

What happens to the materials taken up from the environment by plants?

A

They are returned to the environment and recycled to provide building blocks for future organisms

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68
Q

What materials are cycled through the biotic and abiotic components of an ecosystem?

A
  • carbon
  • water
  • nitrogen
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69
Q

Where is carbon present?

A

In all organisms

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70
Q

What is the carbon cycle?

A

The constant cycling of carbon

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71
Q

How does the carbon cycle work?

A
  • plants and algae remove CO2 from the environment for photosynthesis
  • this carbon is incorporated into the compounds (carbohydrates, fats, proteins) in plants and algae
  • some of the CO2 is returned to the atmosphere when plants and algae respire
  • algae and plants are eaten by animals -animals eat each other - carbon is incorporated into the compounds (carbohydrates, fats, proteins) that make up their bodies
  • animals respire and release CO2
  • when animals, plants and algae die detritus feeders and decomposers feed on their bodies
  • CO2 is released when detritus feeders and decomposers respire
  • combustion releases CO2
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72
Q

What are the different consumers in the food chain?

A

Producer -> primary consumer -> secondary consumer -> tertiary consumer

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73
Q

Example of a producer in the food chain?

A

Maize

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74
Q

Example of a primary consumer in the food chain?

A

Locust

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75
Q

Example of a secondary consumer in the food chain?

A

Lizard

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76
Q

Example of a tertiary consumer in the food chain?

A

Snake

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77
Q

What organisms break down waste products to recycle them?

A

Decomposers (bacteria and fungi) and detritus feeders (detrivores)

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78
Q

What is released when detrivores and decomposers respire?

A

CO2

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79
Q

What does combustion of wood and fossil fuels release into the atmosphere?

A

CO2

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80
Q

When carbon is incorporated into compounds in plants, algae and animals, what form does it take?

A
  • carbohydrates
  • fats
  • proteins
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81
Q

What is the water cycle?

A

The changes to water when it evaporates into the air, condenses in clouds and then precipitates down to Earth

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82
Q

What is evaporation?

A

The process that occurs when water changes from a liquid to gas caused by heat

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83
Q

What is transpiration?

A

The passage of water vapour from a plant to the atmosphere

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84
Q

What is condensation?

A

The cooling of water in the atmosphere changing gas to a liquid

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85
Q

What is precipitation?

A

Water droplets fall from the atmosphere in the form of rain, sleet, snow or hail

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86
Q

What is percolation?

A

When water trickles through gaps in soil and rocks

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87
Q

What is run off?

A

Rainfall that is not absorbed by soil and travels to the ocean

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88
Q

What is the water cycle responsible for?

A

Distributing water across the earth through evaporation, condensation and precipitation

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89
Q

Where is water important?

A
  • solvent - transport medium for solutes
  • transpiration stream - column of water moved up the xylem
  • osmosis - vital for uptake and movement of water
  • expands on freezing - ice floats, insulating organisms in water below
  • metabolic functions - required for photosynthesis, produced in respiration
  • lubricant - synovial fluid
  • support - amniotic fluid, buoyancy for large aquatic animals
  • thermoregulation - evaporation of water cools us down, large bodies of water are thermostable
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90
Q

Why is water needed as a solvent?

A

As a transport medium for solutes

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91
Q

Why is water needed in the transpiration stream?

A

To move water up the xylem

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92
Q

Why is water needed for osmosis?

A

Vital for uptake and movement of water

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93
Q

Why is water needed to expand on freezing?

A

Ice floats, insulating organisms in water below

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94
Q

Why is water needed for metabolic functions?

A

Required for photosynthesis, produced in respiration

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95
Q

Why is water needed as a lubricant?

A

Synovial fluid - between joints

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96
Q

Why is water needed for support?

A

As amniotic fluid, and buoyancy for large aquatic animals

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97
Q

Why is water needed for thermoregulation?

A

Evaporation of water cools us down; large bodies of water are thermostable

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98
Q

What organisms help to decompose biological material?

A
  • detrivores

* decomposers

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99
Q

What are some examples of decomposers?

A

Bacteria and fungi

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100
Q

What are detrivores also known as?

A

Detritus feeders

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101
Q

Why is decomposition vital to the ecosystem?

A

It is vital for the recycling of materials

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102
Q

Examples of detrivores?

A

Woodlice and earthworms

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103
Q

What role do detrivores play in decomposition?

A

Starting the process of decay by breaking plant tissue into much smaller pieces

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104
Q

What effect do detrivores have by breaking plant tissue into smaller pieces?

A

They increase surface area for the action of decomposers

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105
Q

What do detrivores break into smaller pieces?

A

Plant tissue

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106
Q

What are decomposers (microorganisms)?

A

The bacteria and fungi that make things rot

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107
Q

What do decomposers (microorganisms) do?

A

Release enzymes into the dead animal or plant

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108
Q

What do enzymes released by decomposers do?

A

They break down large compounds into smaller soluble ones so they can be absorbed by decomposers

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109
Q

What comes first in the process of decomposition - microorganisms (decomposers) or detrivores?

A

Detrivores

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110
Q

What factors affect the rate of decay?

A
  • temperature
  • availability of water
  • availability of oxygen
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111
Q

How do bacteria and fungi cause decay?

A

By secreting enzymes which break down biological material

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112
Q

What do microorganisms specifically release during decomposition?

A
  • mineral ions

* carbon dioxide

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113
Q

Why do dead animals and plants decay more quickly at higher temperatures?

A
  • as temperature increases, rate of reaction increases - the enzymes secreted by decomposers work better at higher temperatures -> more energy -> more collisions between enzymes and substrates
  • if temperature is too high enzymes will denature and decay will stop
114
Q

Why do dead animals and plants decay more quickly when more oxygen is available?

A

detrivores and decomposers are causing this decay -> they need oxygen to respire

115
Q

Why do dead animals and plants decay more quickly in moist conditions?

A

Water is needed for metabolic processes

116
Q

What type of process is the souring of milk?

A

Fermentation; takes places in the absence of oxygen

117
Q

What do bacteria in pasteurised milk do?

A

Breakdown lactose to form lactic acid - which lowers pH so milk tastes sour

118
Q

In the required practical, why will the pH of the milk fall?

A

Due to the production of fatty acids

119
Q

In the required practical, what is used to speed up the process of fermentation?

A

Lipase

120
Q

What is the difference between the model and the natural decay of milk?

A
  • the model uses lipase -> pH decreases due to fatty acids

* natural decay -> pH decreases due to lactic acid

121
Q

What is cresol red?

A

An indicator that is purple in alkaline solutions but when pH drops below 8.3 it becomes yellow

122
Q

What colour is cresol red in alkaline solutions?

A

Purple

123
Q

When will the cresol red indicator turn yellow?

A

When pH drops below 8.3

124
Q

Examples of organic material that can be composted?

A
  • waste food
  • vegetable peelings
  • paper
  • leaves/grass cuttings
125
Q

What is released during the composting process?

A

Carbon dioxide from respiration

126
Q

What is compost used for?

A

A natural fertiliser for plants or crops

127
Q

What does composting do?

A

Recycles nutrients back into the soil, improving crop growth

128
Q

How do farmers provide optimum conditions for rapid decay of biological matter?

A
  • warmth - keep in the sun
  • moisture - sprinkle water on if dry, cover in plastic cover to hold in moisture
  • air - turn over compost with rake to keep aerated
129
Q

What could happen if compost overheats?

A

Could cause methane to be produced instead of just carbon dioxide

130
Q

Examples of where decay micro organisms are useful?

A
  • compost
  • gardeners putting manure on their roses etc.
  • farmers decaying waste animal matter produced on farm
  • sewage works
131
Q

What is produced in anaerobic digestion?

A

Biogas

132
Q

What is biogas?

A

A flammable mixture of gases

133
Q

How is biogas formed?

A

When bacteria break down plant or animal waste material in anaerobic conditions

134
Q

What is biogas composed of?

A

Mainly methane - it varies depending on what is put into generator and what bacteria are present

135
Q

What does the composition of biogas depend on?

A
  • what is put into the generator

* which bacteria are present

136
Q

What is the optimum temperature for bacteria in a biogas generator?

A

30*C

137
Q

Why do biogas generators generate heat?

A

The reactions are exothermic

138
Q

Inputs to biogas generators?

A
  • animal dung
  • farm waste
  • garden waste
139
Q

Outputs of biogas generators?

A
  • methane for cooking, heating or refrigeration

* slurry - can be used as fertiliser

140
Q

Why do biogas generators work best in hot countries?

A

They work best at 30*C

141
Q

Why are many biogas generators sunk into the ground?

A

For good insulation

142
Q

Advantages of the floating draw biogas generator?

A
  • easy construction
  • easy to operate
  • steady gas pressure produced
  • reliable - well trialed technology
143
Q

Disadvantages of the floating draw biogas generator?

A
  • metal holder is expensive

* metal holder may rust

144
Q

Advantages of the fixed dome biogas generator?

A
  • initial cost low
  • well insulated
  • long useful life - no moving or rusting parts
145
Q

Disadvantages of the fixed dome biogas generator?

A
  • gas pressure fluctuates

* sealing of the gas holder is not always right

146
Q

Which changes in the environment can impact the distribution of species within an ecosystem?

A
  • a change in the availability of water
  • a change in temperature
  • a change in the composition of atmospheric gases
147
Q

How may changes in the environment come about?

A
  • naturally - seasonal, geographical changes

* due to human activity

148
Q

What is the general impact that humans have on the land?

A

More resources are used, more waste is produced

149
Q

What happens if waste is not handled appropriately?

A

It may cause pollution of air, water and land

150
Q

Why is there exponential growth of the human population?

A
  • lack of predators
  • advances in medicine
  • increased efficiency of food production
  • modern farming methods which increase productivity etc.
151
Q

What is water pollution caused by?

A
  • fertilisers
  • toxic chemicals
  • sewage
152
Q

How do humans reduce the amount of land available for other animals?

A

By:

  • building
  • quarrying
  • farming
  • dumping waste
153
Q

What happens when fossil fuels are burned?

A

Acidic gases and smoke are released and pollute the air

154
Q

What can burning fossil fuels lead to?

A

Breathing problems, and the formation of acid rain

155
Q

What is smog?

A

A haze of small particles and acidic gases that can be seen in the air in cities

156
Q

What can smog be made of?

A
  • sulphur dioxide
  • nitrogen oxides

etc.

157
Q

What are some pollutants from fuels that are in the atmosphere?

A
  • sulphur dioxide
  • particulate matter
  • nitrogen oxides
158
Q

How do fertilisers cause water pollution?

A
  • fertiliser drains through soil into water so algae grow

* when algae die the bacteria in the water increases and use the oxygen up, killing the fish

159
Q

What is the process called that means fertiliser can cause water pollution?

A

Eutrophication

160
Q

How do toxic chemicals cause water pollution?

A

Can pollute water and kill animals and plants, reducing biodiversity

161
Q

How can sewage cause water pollution?

A
  • can cause an increase in the number of bacteria in the water
  • bacteria remove oxygen for respiration and organisms die
162
Q

Where may land pollution come from?

A
  • landfill

* toxic chemicals from industry and households

163
Q

Examples of some non-renewable energy resources that are being used up?

A
  • uranium
  • natural gas
  • propane
  • coal
164
Q

Why is land pollution a problem?

A
  • pest resurgence
  • reduction in wild flower biodiversity
  • persist in environment = long term damage
  • affect top carnivore if persists in food chain
165
Q

How can pest resurgence be caused by land pollution?

A

Land pollution may kill insects such as predators of the pest

166
Q

How can reduced flower biodiversity be caused by land pollution?

A

Land pollution may kill wild plants which act as food plants for beneficial insects

167
Q

When does bioaccumulation occur?

A

When toxic chemicals such as pesticides are taken up by predators in the food chain

168
Q

How do toxins get passed in the food chain to cause bioaccumulation?

A

From the primary consumers to the secondary and tertiary etc.

169
Q

Why does a toxin accumulate in larger amounts further down the food chain?

A

Organisms consume larger numbers of the organism below them in the food chain

170
Q

What happens when acid rain reaches the earth?

A

It flows across the ground in surface runoff, enters water systems and sinks into the soil

171
Q

How does acid rain occur?

A
  • gases from combustion of fossil fuels are released into the atmosphere (e.g. sulphur dioxide, nitrogen dioxides)
  • the wind spreads the acidic gases over 100s of miles
  • acidic gases are dissolved in the rain and snow
  • plants, animals and lakes are damaged by acid rain
172
Q

What effects does acid rain have?

A
  • makes waters acidic - increased aluminium in the water - killing aquatic animals
  • damages forests - leaches mineral ions out of soil and aluminium is released into the soil - leaves damaged
173
Q

How does acid rain affect aquatic animals?

A
  • waters are made acidic

* (toxic) aluminium in the water - enters lakes and streams - kills aquatic animals

174
Q

How does acid rain affect forests?

A
  • leaches essential mineral ions out of soil
  • releases (toxic) aluminium into the soil
  • leaves directly damaged
175
Q

What is the meaning of biodiversity?

A

The variety of all the different organisms on earth, or within an ecosystem

176
Q

Why is having high biodiversity important?

A

It ensures the stability of ecosystems - because it reduces the dependence of one species on another for food and shelter

177
Q

How does global warming occur?

A
  • energy from the sun is absorbed by earth
  • normally the sun radiates the energy back out of the atmosphere
  • greenhouse gases absorb the energy
  • some energy is radiated back to earth
  • results in global warming
178
Q

What are the consequences of global warming?

A
  • rising sea levels leading to habitat loss
  • changes in distribution of organisms
  • changes to migration patterns
  • less biodiversity
179
Q

How does global warming make sea levels rise and lead to habitat loss?

A
  • sea warms and expands so sea level rises
  • also makes ice melt so water trapped on land runs into the sea e.g. glaciers
  • leads to flooding in low-lying areas
180
Q

How does global warming cause changes to the distribution of organisms?

A
  • some species become more widely distributed if they need warmer temperatures and can thrive over a larger area
  • some species that need cooler temperatures have smaller ranges and can thrive over smaller areas
181
Q

How does global warming cause a change in migration patterns?

A

animals (e.g. birds) migrate

• for example, birds in Africa moving back to summer breeding grounds earlier than before

182
Q

How does global warming cause reduced biodiversity?

A

Some species may not be able to adapt to a change in climate - won’t survive and become extinct

183
Q

How does an increase in human population affect development and therefore land use?

A

Increased human population leads to increased development and there increased land use

184
Q

What are the main reasons for deforestation?

A
  • to clear land for farming (e.g. cattle)

* to grow crops for biofuel

185
Q

What are the consequences of deforestation?

A
  • less biodiversity - fewer habitats
  • more carbon dioxide released into atmosphere - global warming
  • fewer trees to ‘lock up’ carbon dioxide during photosynthesis - more in the atmosphere
  • destruction of peat bogs leading to release of carbon dioxide
186
Q

What are bogs?

A

Areas of land that are acidic and waterlogged

187
Q

Why is there a lack of decay in bogs?

A

There is a lack of oxygen

188
Q

How is peat formed?

A

When partly rotted plants in bogs build up to form a soil like material

189
Q

Why are peat bogs often drained?

A
  • so the area can be used as farmland

* so the peat can be dried to burn as fuel or be sold as compost

190
Q

What are the problems of peat bogs?

A
  • draining peat means more air can get to it = more decomposition = microbes release carbon dioxide = global warming
  • carbon dioxide is released when peat burns = global warming
  • destroying bogs reduces habitats and therefore biodiversity
191
Q

What are the general effects of rising sea surface temperatures and rising sea levels?

A
  • people become displaced from their homes
  • increased population density and demands on land
  • river delta threatened - sea water moves upstream
  • coral reefs bleached
  • increased numbers of tropical storms
  • warmer water temperatures - human health threatened e.g. cholera
192
Q

What have scientists done to reduce negative effects of humans on biodiversity?

A
  • breeding programmes
  • protection and generation of rare habitats
  • reintroduction of hedgerows in agricultural areas to increase biodiversity
  • reduction of deforestation and and CO2 emissions by some governments
  • recycling resources rather than dumping waste
193
Q

Examples of breeding programmes that will reduce negative effects of humans on biodiversity?

A

In zoos, then releasing animals back into the wild without being humanised

194
Q

Examples of rare habitats that can be protected to reduce negative effects of humans on biodiversity?

A
  • marshlands
  • heathlands
  • coral reefs
  • mangrove swamps
195
Q

Examples of recycling instead of dumping waste that will reduce negative effects of humans on biodiversity?

A

Developing biodegradable plastic

196
Q

What conflicting pressures are there which can affect how biodiversity is maintained?

A
  • costs money
  • can come at a cost to local people’s livelihood
  • may be conflict in protecting food security
  • development can affect the environment
197
Q

An example of how costs can affect how biodiversity is maintained?

A

Governments may pay farmers a subsidy to reintroduce hedgerows - costs money to check these programmes are being followed

198
Q

An example of how other people’s livelihood can affect how biodiversity is maintained?

A

Reducing deforestation means people employed in tree felling could be left unemployed and move away to find work - affecting the local economy

199
Q

An example of protecting food security can affect how biodiversity is maintained?

A

Farmers may kill pests (locusts, foxes) to protect crops and livelihood so more food can be grown - affecting food chain and biodiversity

200
Q

An example of how development can affect how biodiversity is maintained?

A

For housing development on the edge of towns or new agricultural land in developing countries - untouched land with high biodiversity used for development

201
Q

How can indicator species measure pollution levels?

A

The presence/absence of certain organisms indicates how much pollution there is

202
Q

What is the most common source of air pollution?

A

The combustion of fossil fuels

203
Q

Example of an indicator species for air pollution?

A

Lichen

204
Q

What are lichens?

A

Plants that grow in exposed places e.g. rocks, tree bark

205
Q

How do lichens indicate the amount of pollution in an area?

A
  • rainwater contains just enough nutrients to keep them alive
  • air pollutants dissolved in rainwater can damage them and prevent growth
206
Q

What is biomass?

A

The amount of dry biological matter (kg)

207
Q

What is a carnivore?

A

An organism that eats meat - consumer

208
Q

What is a herbivore?

A

An organism that eats producers (green plants)

209
Q

What is a predator?

A

An organism which hunts for food (carnivores)

210
Q

What is prey?

A

Organisms which are eaten by predators (herbivores or carnivores)

211
Q

What is a producer?

A

A green plant

212
Q

How is energy from the sun passed on through a food chain?

A

Radiation from the sun is the source of energy for organisms on earth. Energy is trapped by green plants and passed to animals in food chains

213
Q

What is a trophic level?

A

A feeding level in a food chain

214
Q

How can trophic levels be represented?

A

Using numbers - starting at level one with plants and algae

215
Q

What are apex predators?

A

Carnivores with no predators

216
Q

What are decomoposers?

A

Microorganisms that break down dead plant and animal matter by secreting enzymes

217
Q

What happens to the amount of biomass and energy in organisms as a food chain progresses?

A

It decreases throughout the chain

218
Q

How much biomass is transferred from one trophic level to the one above?

A

10%

219
Q

What are losses of biomass in the food chain due to?

A
  • not all ingested material being absorbed (some faeces)
  • some absorbed material lost as waste (CO2 and water in respiration)
  • glucose used in respiration
220
Q

Why do carnivores produce less waste than herbivores?

A

meat is easier to digest than vegetation, however some indigestible materials (fur, bones, teeth) become faeces

221
Q

What happens when animals eat excess protein?

A

It cannot be stored and is broken down into urea and passed out in urine

222
Q

How is biomass lost through movement?

A

some biomass used for respiration:

  • movement uses energy
  • muscles heat as they contract
223
Q

Why do mammals need to eat more food than amphibians, reptiles and fish?

A

Mammals need to maintain a body temperature higher than their surroundings - more energy from respiration transferred as heat

224
Q

What is extracellular digestion?

A

When decomposers break down dead animal and plant waste by secreting enzymes on it

225
Q

Problem with pyramids of numbers?

A

Do not accurately reflect what is happening to biomass

226
Q

Why does the number of organisms at each trophic level decrease?

A

A large amount of energy in the biomass of plants supports a smaller amount of herbivore biomass etc

227
Q

How is the efficiency of a biomass transfer calculated?

A

biomass transferred to next level / biomass availible at previous level x100

228
Q

An example to demonstrate how a pyramids of biomass is more useful than a pyramid of numbers?

A

1 oak tree could support lots of organisms, but it has a large biomass - showing energy loss throughout food chain

229
Q

What are cyclic fluctuations?

A

When the numbers of predators and prey fluctuate in a regular pattern

230
Q

Example of cyclic fluctation?

A

foxes and rabbits:

  • more food (grass) - rabbit number increases
  • more food for foxes - number increases
  • rabbit number decreases
  • no food for foxes so number decreases
  • fewer foxes - rabbits increase

and so on

231
Q

What is food security?

A

Having enough food to feed a population

232
Q

What biological factors are threatening food security?

A
  • increase in birth rate
  • changing diets in developed countries
  • new pests and pathogens
  • environmental changes e.g. famine
  • cost of agricultural inputs
  • conflict
233
Q

In general, how can the efficiency of food production be improved?

A

By restricting energy transfer from food animals to the environment

234
Q

What farming methods can be used to minimise energy loss from food animals?

A
  • limiting their movement
  • controlling the temperature of their surroundings
  • feed high protein foods to increase growth
  • reduce number of stages in food chain
235
Q

Advantages of intensive farming?

A
  • lots of animals in a small space
  • little food wastage
  • minimum energy lost from heat loss or movement
  • maximum weight gain
  • cheaper eggs/meat
236
Q

Disadvantages of intensive farming?

A
  • chickens not able to behave naturally - debeaked
  • large barns need heating and lighting
  • chicken legs break - cannot hold own weight
  • risk of disease - closely packed together
237
Q

Advantages of free range farming?

A
  • cattle behave naturally, less stressed

* feeding on grass means no contamination

238
Q

Disadvantages of free range farming?

A
  • animals may take longer to gain weight as they are more active
  • more land needed to provide grazing and hay
239
Q

Solutions to overfishing?

A
  • larger mesh size
  • bans on fishing during breeding season
  • avoiding breeding grounds
  • stricter quotas on amount and type of fish caught
240
Q

What fungus is useful for producing mycoprotein?

A

fusarium

241
Q

What is mycoprotein?

A

A protein-rich food suitable for vegetarians

242
Q

What do fermenters enable in mycoprotein production?

A

For microorganisms to be grown on an industrial scale

243
Q

How do fermenters obtain the maximum amount of product?

A

By reacting to changes and keeping conditions as stable as possible

244
Q

What is the role of oxygen in a fermenter?

A
  • for respiration
  • filtered to remove dust/microbes
  • enters at base and bubbles through the liquid in the fermenter
245
Q

What is the role of the paddle stirrer in a fermenter?

A
  • keeps microbes in suspension

* maintains constant temperature so oxygen and food are evenly spread

246
Q

What is the role of the warm water outlet in a fermenter

A

• allows heat released from respiring microbes to leave the water-cooled jacket

247
Q

What is the role of the food inlet in a fermenter?

A
  • allows nutrients to enter at a controlled rate

* this ensures that microbes are kept at correct stage of growth

248
Q

What is the role of the steam inlet in a fermenter?

A

• raise temperature of contents to optimum

249
Q

What is the role of the pH/temperature probe in a fermenter?

A
  • CO2 would alter pH and then affect activity of enzymes in microbes
  • ensure the conditions remain constant
250
Q

What is the role the outlet - harvest line - in a fermenter?

A

• enables product to be harvested

251
Q

How long does the fermenter run in mycoprotein production?

A

Six weeks

252
Q

What conditions is mycoprotein grown in?

A
  • aerobic

* temperature no higher than 35*C

253
Q

What does the fungus in mycoprotein production require?

A

Glucose for respiration

254
Q

How is temperature controlled in the making of mycoprotein?

A

A cooling water jacket

255
Q

Why does temperature need to be controlled in mycoprotein production?

A
  • aerobic respiration produces heat

* if temperature goes above 35*C

256
Q

What happens to the waste gases produced in a fermenter during mycoprotein production?

A

Leave the fermenter at the top (such as CO2)

257
Q

What happens to the mycoprotein after it is removed from the fermenter?

A
  • heated to break down substances that would otherwise cause kidney problems
  • dried in centrifuge
  • flavourings added
258
Q

How does temperature control in a fermenter differ to that in a biogas generator?

A

Fermenter - above 35*C and growth slowed - AEROBIC

Biogas generator - needs to be above 30*C - ANAEROBIC fermentation

259
Q

In terms of minerals, what does mycoprotein lack?

A

Iron

260
Q

How does genetic engineering help to treat diabetes?

A

A genetically modified bacterium produces human insulin which is used when purified

261
Q

What two cells are used to produce human insulin from bacteria?

A
  • human cell with insulin gene in DNA

* bacterium cell with ring of DNA (a plasmid)

262
Q

How is human insulin produced from genetically modified bacteria?

A
  1. insulin gene cut out of DNA by restriction enzyme
  2. plasmid taken out of bacterium and split open by enzyme
  3. insulin inserted into plasmid using enzyme
  4. plasmid taken up by bacterium
  5. bacterium multiplies and grown in fermenter
263
Q

What does a restriction enzyme do?

A

Recognises specific sequences of DNA and cuts it at these points

264
Q

What happens to DNA after is has been ‘cut’ using a restriction enzyme?

A

One of the DNA strands is left with unpaired bases - a sticky end

265
Q

What is a sticky end?

A

When DNA has been cut by restriction enzyme and one of the DNA strands is left with unpaired bases

266
Q

What is the plasmid of a bacterium taken out using during genetic engineering?

A

The same restriction enzyme as the insulin gene - leaving the same sticky ends

267
Q

Where can genes be transferred to in genetic engineering?

A
  • bacteria

* plants

268
Q

How are GM crops created?

A

New genes transferred to crop plants

269
Q

When are genes transferred in GM crops?

A

At an early stage of development

270
Q

Why are genes transferred so early in GM crops?

A

So that the organism develops with the desired characteristics

271
Q

An example of a GM crop?

A

Golden rice

272
Q

How is golden rice engineered?

A
  • genes involved in beta-carotene production are obtained from other species
  • then they’re introduced to the white rice genome
273
Q

What is the benefit of golden rice?

A

Increased vitamin A content (25 times)

274
Q

Arguments for GM crops?

A
  • higher crop yields
  • resistant to herbicides
  • reduces pesticide use
  • safe for human consumption
  • help developing world
  • preserves habitats
  • better shelf life
  • produces plants better for harsher habitats
275
Q

How do GM crops reduce pesticide use?

A

Some crops resistant to viruses and insect pests

276
Q

How do GM crops preserve habitats?

A

Less land needed for agriculture

277
Q

Arguments against GM crops?

A
  • effect on wild flowers and insects
  • mainly benefits large GM companies
  • unknown long term health risks
  • affect wild life
  • increasing yields won’t help developing world
  • cross contamination
278
Q

Why might GM crops affect wildlife?

A

Weeds killed could be a source of food for animals

279
Q

Why might cultured meat slow down the rate of global warming?

A
  • less methane produced by cows

* less deforestation to cater for grazing

280
Q

Describe how mycoprotein is produced

A
  • the fungus fusarium is grown in a fermenter
  • in aerobic conditions
  • it needs glucose
  • mycoprotein is harvested and purified

AQA GCSE Biology (9-1) (7 decks)

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