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GCSE Biology > Topic 9: Ecosystems & Cycles > Flashcards

Topic 9: Ecosystems & Cycles Flashcards

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1
Q

What is a habitat?

A

The place where an organism lives

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2
Q

What is an individual?

A

A single organism

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3
Q

What is a population?

A

All the organisms of one species in a habitat

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4
Q

What is a community?

A

The populations of different species living in a habitat

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5
Q

What is an ecosystem?

A

A community of organisms along with all the non living conditions

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6
Q

What is interdependence?

A

Each species in a community depending upon other species for things e.g. food and shelter

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7
Q

What are the 2 types for relationships between organisms?

A
  1. Mutualism
  2. Parasitism
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8
Q

What is mutualism?

A

When both organisms benefit in a relationship

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9
Q

What is parasitism?

A

When a parasite lives on or in a host organisms and they benefit but the host doesn’t and may be harmed

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10
Q

If there’s a change in the population of a species that has an interdependence relationship with another species, what can happens to the other species?

A

It can be affected by this change

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11
Q

What is an abiotic factor?

A

Non living variables that can influence where organisms can live and the organisms themselves

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12
Q

What is a biotic factor?

A

Interactions associated with living organisms that can affect organisms in a community

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13
Q

What is a trophic level?

A

The level a specific organism occupies in a food chain

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14
Q

What are examples of a parasitic relationship?

A

Headlice and humans
Mosquitos and humans

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15
Q

What are examples of a mutualistic relationship?

A

Coral and algae
Hammerhead sharks and angel fish

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16
Q

Examples of biotic factors?

A

Competition
Predation
Disease

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17
Q

Examples of abiotic factors?

A

Amount of water
Temperature
Light intensity
Levels of pollutants

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18
Q

What is the cycle of predation?

A

Number of predators increases…
Number of prey decreases…
Number of predators decreases…
Number of prey increases

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19
Q

What is biomass?

A

The mass of living material

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20
Q

What is a pyramid of biomass?

A

A diagram showing the relative amounts of biomass at each trophic levels

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21
Q

What is the order of the trophic levels? Start with the first to the last

A

Producer —> primary consumer —> secondary consumer —> tertiary consumer

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22
Q

What does the direction an arrow points in on a food web/chain show?

A

How biomass is transferred

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23
Q

What is the length of a bar proportional to on a pyramid of biomass?

A

The length of a bar is proportional to the biomass at each level

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24
Q

Steps to drawing a pyramid of biomass?

A
  1. Look at all of the biomasses provided for each organism and make a key
  2. Relate biomass of the first organism to the key and draw up the first bar - the length of the bar should be proportional to the biomass at the level
  3. Repeat the step until you’ve done all of the organisms
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25
Q

How is energy transferred starting with the sun?

A
  1. Energy from the sun is transferred by light to producers
  2. A small percentage of the energy that hits producers is converted into glucose during photosynthesis and is stored as biomass
  3. Only some energy from the producer is then passed on to the primary consumer and so on
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26
Q

What are the 4 reasons why energy is lost between trophic levels?

A
  1. Not all material ingested by organisms can be absorbed so some of it is lost as faeces
  2. Some of the energy is transferred from the organisms to their surroundings as heat
  3. Lots of energy is used for respiration rather than being used to build new biomass
  4. Energy is also used for the organisms to grow
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27
Q

What are the 3 impacts of energy loss during energy transfer to trophic levels?

A
  1. Results in fewer organisms at each trophic level
  2. Gives a pyramid of biomass a triangular shape
  3. Results in there being rarely more than 5 trophic levels in a food chain
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28
Q

How to calculate efficiency of energy transfer?

A

Efficiency of energy transfer = energy transferred to next level/energy available at previous level x 100

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29
Q

What is biodiversity?

A

The variety of living organisms in an ecosystem

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30
Q

What is eutrophication?

A

A process in which an excess of nutrients builds up in water

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31
Q

What can eutrophication lead to?

A

A decrease in biodiversity

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32
Q

Describe the process of eutrophication

A
  1. Fertilisers and excess nitrates run into a stream or any body of water
  2. Excess nitrates cause the algae in the water to grow faster creating an algal bloom
  3. The algal bloom blocks out light from entering the stream meaning the plants can’t photosynthesise - so they die and decompose
  4. Microorganisms then eat the decomposing plants and multiply - using up oxygen in the water
  5. The organisms that need oxygen to survive then die
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33
Q

What are the 3 ways that fish farming can reduce biodiversity?

A
  1. Waste and food from nets can enter open water and cause eutrophication
  2. Parasites can escape from the farm and infect wild animals - which can kill them
  3. Farmed fish can escape and compete with wild populations
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34
Q

What are non indigenous species?

A

Species that don’t naturally occur in one area

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35
Q

Why can non indigenous species cause native species to die out?

A

They can outcompete native species
They can bring new diseases to a habitat that the native species aren’t familiar to

36
Q

What are the 3 main ways that biodiversity is lost?

A
  1. Eutrophication
  2. Fish farming
  3. Non indigenous species
37
Q

What is an advantage of fish farming?

A

Reduces fishing of wild fish

38
Q

What is an advantage of non indigenous species?

A

May increase biodiversity if it doesn’t affect the native species
May kill the native species - which is good if the native species is bad

39
Q

What are the 3 ways of improving biodiversity?

A
  1. Reforestation
  2. Conservation schemes
  3. Breeding programmes
40
Q

What is reforestation?

A

Replanting trees where they’ve been removed

41
Q

How can reforestation improve biodiversity?

A

Trees are habitats to many species - having more trees means more variety of animals can live in the area

42
Q

What are examples of conservation schemes?

A

Protecting species natural habitats
Protecting species in safe areas e.g. zoos

43
Q

How can conservation projects increase biodiversity?

A

They can give a safe space for species to thrive and they also protect habitats

44
Q

What are breeding programmes?

A

When endangered species are bred to increase population

45
Q

How can breeding programmes maintain biodiversity?

A

Can stop the extinction of species

46
Q

What are 3 benefits of maintaining biodiversity?

A
  1. Preserves cultural heritage
  2. Ensures there’s enough food for future generations
  3. Saves potential future medicines
47
Q

What is food security?

A

Having enough food to feed a population that is accessible, safe to eat and has the right balance of nutrition

48
Q

What 5 factors affect food security?

A
  1. Population growth
  2. Changing diets
  3. Environmental changes caused by human activity
  4. New pests and pathogens
  5. Sustainability
49
Q

How can population growth affect food security?

A

As global population increases, so does the demand for food production - quality of food may worsen

50
Q

How can changing diets affect food security?

A

If there’s an increased consumption of meat and fish, there’s less crops - the crops are used to feed animals so there’s fewer available for humans

51
Q

How can environmental changes caused by human activity affect food security?

A

The burning of fossil fuels can lead to climate change - reduces crop yield
Soil pollution - reduces crop growth

52
Q

How can new pests and pathogens affect food security?

A

Crops and livestock can be damaged - less food for humans

53
Q

How can sustainability affect food security?

A

Some crops are grown for biofuels - this may need to be limited so there’s more crops for food for later generations
High input costs of farming means some areas will not be farmed in the future - may reduce food production there

54
Q

Why are sustainable methods of food production necessary?

A

To feed everyone now and in the future

55
Q

What is potable water?

A

Water that’s drinkable

56
Q

Describe the water cycle

A
  1. Water evaporates from a body of water and water will evaporate through transpiration from leaves
  2. This water vapour will then condense into clouds
  3. Then precipitation will occur and water will come down in a form of precipitate e.g. rain
  4. This water then return back into the trees and water
57
Q

In time of drought, what are the 2 ways potable water can be produced?

A
  1. Reverse osmosis
  2. Thermal desalination
58
Q

Why is the water cycle important?

A

All living organisms need water, all organisms will eventually die without it
Important for photosynthesis

59
Q

How does reverse osmosis produce potable water?

A

Water is forced at a high pressure through a partially permeable membrane

60
Q

How does thermal desalination produce potable water?

A

Salt water is boiled and then the steam is condensed and collected

61
Q

Describe the carbon cycle

A
  1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion
  2. Carbon dioxide is then absorbed by producers to make carbohydrates in photosynthesis
  3. Animals feed on the plants, passing the carbon compounds along the food chain
  4. These animals then exhale carbon dioxide returning it to the atmosphere during respiration but eventually die
  5. The dead animal and plant organisms are eaten by decomposers and carbon in their bodies is returned to the atmosphere as carbon dioxide
62
Q

Describe the nitrogen cycle

A
  1. Nitrogen gas from the air is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules
  2. Ammonia from the Haber process and fertilisers is converted to nitrates by nitrifying bacteria in the soil
  3. Plants absorb nitrates from the soil and use these to build up proteins, the plant may be eaten by an animal and the nitrates will become a part of the animals protein
  4. The animal will die and decomposers break down the bodies of dead organisms into ammonia
  5. Nitrifying bacteria converts ammonia to nitrites then to nitrates
  6. Denitrifying bacteria in the soil break down nitrates and return nitrogen back to the air
  7. Nitrogen fixing bacteria in legumes converts nitrogen gas into nitrates
63
Q

What does nitrogen fixing bacteria do?

A

Nitrogen gas —> nitrates

64
Q

What does nitrifying bacteria do?

A

Ammonia —> nitrites —> nitrates

65
Q

What does denitrifying bacteria do?

A

Nitrates —> nitrogen gas

66
Q

What do decomposers do?

A

Break down urea from waste and proteins from dead organisms to release ammonia

67
Q

Why do nitrates need to be returned back to soil after harvest?

A

Crops take up the nitrates from soil as they grow
Crops are then harvested so nitrogen isn’t returned to the soil and thus needs to be replaced

68
Q

What are the 2 ways of increasing nitrates in soil?

A
  1. Adding fertilisers to soil
  2. Crop rotation
69
Q

What is the process of crop rotation?

A

Different crops are grown in the same field each year in a cycle
The cycle usually includes a nitrogen fixing crop - which has nitrogen fixing bacteria in its roots which fix nitrogen gas

70
Q

What are the 2 types of fertilisers that can be added to soil?

A
  1. Animal manure or compost (decomposed organic matter) - nitrogen compounds released into soil as these decompose
  2. Artificial fertilisers - contain nitrates
71
Q

What is an indicator species?

A

Organism that are very sensitive to changes in their environment and so can be used to investigate pollution

72
Q

What are the 2 ways to investigate pollution using indicator species?

A
  1. Do a survey to see if species is present or absent - quick process but doesn’t show how polluted an area is
  2. Count the number of times the species occurs in an area - allows you to compare areas
73
Q

What organisms are present when there is low water pollution?

A

Stonefly larvae
Freshwater shrimp

74
Q

What organisms are present when there is high water pollution?

A

Blood worms
Sludgeworms

75
Q

What organisms are present when there is low air pollution?

A

Bushy lichen
Black spot fungus (on rose leaves) - no sulfur dioxide

76
Q

What organisms are present when there is high air pollution?

A

Crusty lichen (or no lichen at all)

77
Q

Advantages of using indicator species?

A

They are easy and cost effective

78
Q

Disadvantages of using indicator species?

A

They aren’t accurate - factors other than pollution can affect their numbers

79
Q

What are 3 things that increase the rate of decomposition? Why?

A
  1. Warm temperatures - speeds up enzyme controlled reactions in decomposers
  2. Moist conditions - decomposers need to water to reproduce
  3. Plenty of oxygen - decomposers need oxygen for anaerobic respiration
80
Q

What is the equation for rate of decomposition?

A

Rate of decomposition = amount of decomposition/time

81
Q

Why do compost bins increase rate of decomposition?

A

They keep decomposing bacteria moist and alive
Mesh sides in the bins allow for oxygen to come in
Decomposers generate heat

82
Q

What are 3 methods of food preservation that decrease the rate of decomposition? Why?

A
  1. Chilling/freezing - low temperature so growth rate of decomposers slows down
  2. Drying - water and moistness is removed
  3. Canning - airtight so no oxygen is available and cans are sterilised to kill decomposers
83
Q

FINDING ABUNDANCE OF ORGANISMS CORE PRACTICAL: What is the process of this experiment?

A
  1. Place a 1m^2 quadrat at random in a field
  2. Count all the daisies within it
  3. Repeat steps 1 and 2 several times and work out the mean number of daisies per quadrat
    (Mean = total number of organisms/number of quadrats)
  4. Multiply the size of the entire area by the number of organisms per m^2 to find an estimate of the population
84
Q

FINDING ABUNDANCE OF ORGANISMS CORE PRACTICAL: What can this experiment do?

A

Predict the population size of small organisms

85
Q

FINDING DISTRIBUTION OF ORGANISMS CORE PRACTICAL: What is the process of this experiment?

A
  1. Mark out a 10m line using a tape measure (belt transect)
  2. Count the daisies in quadrats placed at regular intervals along the line
  3. Measure the moisture content of the soil at the same intervals along the line
  4. Draw graphs to see if the abundance of daisies correlates with the moisture content along the gradient to find out how organisms are distributed along a gradient
86
Q

FINDING DISTRIBUTION OF ORGANISMS CORE PRACTICAL: What can this experiment do?

A

Find out HOW organisms are distributed along a gradient using a belt transect (predict what the reason for this is)

GCSE Biology (9 decks)

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