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Biology yr11 > topic 9 Ecosystems and material systems > Flashcards

topic 9 Ecosystems and material systems Flashcards

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1
Q

what is an ecosystem?

A

An ecosystem is the interaction of a community with non-living (abiotic) parts of the environment.

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2
Q

name 4 things that plants may compete for?

A

light
space
water
and mineral ions

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3
Q

name 4 things animals may compete for?

A

space
food
water
and mating partners

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4
Q

what is an abiotic factor?

A

a non-living factor that can affect a community.

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5
Q

what is a biotic factor?

A

a living factor that can affect a community.

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6
Q

name the 7 abiotic factors that can affect a community

A 
light intensity
temperature
moisture levels
soil PH and mineral content
wind intensity and direction
carbon dioxide levels
Oxygen levels for aquatic animals
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7
Q

explain how light intensity as an abiotic factor affects a community?

A

light intensity is required for photosynthesis
the rate of photosynthesis affects the rate at which a plant grows
plants can be food sources or shelter for many organisms

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8
Q

explain how temperature as an abiotic factor affects a community?

A

temperature also affects the rate of photosynthesis

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9
Q

explain how moisture levels as an abiotic factor affects a community?

A

Both plants and animals need water to survive

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10
Q

explain how soil PH and mineral levels as an abiotic factor affects a community?

A

soil PH affects the rate of decay and therefore how fast mineral ions return to soil.
Different species of plants thrive in different nutrient concentration levels.

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11
Q

explain how wind intensity and direction as an abiotic factor affects a community?

A

wind affects the rate of transpiration in plants
transpiration affects the tempreture as a plant, and the rate of photosynthesis because it transports water and mineral ions in leaves.

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12
Q

explain how carbon dioxide levels as an abiotic factor affects a community?

A

CO2 affects the rate of photosynthesis in plants.

It also affects the distribution of organisms as some thrive in high CO2 environments

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13
Q

explain how oxygen levels as an abiotic factor affects an aquatic community?

A

levels in water vary greatly, unlike oxygen levels in air.

most fish need a high concentration of oxygen to survive aswell.

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14
Q

Name the 4 biotic factors that affect a community

A

Food availability
new predators
new pathogens
competition

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15
Q

what is interdependence?

A

interdependence describes how organisms in a community depend on other organisms for vital services

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16
Q

name some benefits of having a stable community

A

population sizes remain roughly consistent
when they are lost it is very hard to replace them
examples are tropical rainforests and coral reefs.

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17
Q

what is a stable community?

A

a stable community is a community in which all biotic and abiotic factors are in balance.

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18
Q

what is a parasitical relationship?

A

a parasitical relationship is one that involves one species taking nutrients to the detriment of another species.

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19
Q

what is a parasite?

A

a parasite is the smaller species that lives directly within or on a larger species and benefits at the expense of the other species.

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20
Q

what is a mutualistic relationship?

A

A mutualistic relationship is where a smaller species that lives directly within or on a larger species it provides some benefit or resource to the other species, for instance providing nutrients

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21
Q

give an example of a parasitical relationship?

A

In humans, the ​tapeworm ​is a parasite that lives inside the gut. It ‘steals’ nutrients from the host and can lead to ​malnutrition.

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22
Q

give an example of a mutualistic relationship?

A

algae and fungi live together to form lichens. ​Algae can photosynthesise to provide sugars for the fungi, whereas the fungi allow the algae to live in more extreme conditions than those under which it would normally thrive.

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23
Q

how can we calculate the number of certain living organisms in a given area?

A

by using quadrats and transects.

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24
Q

how do you complete a transect/

A
  • Divide the field into 100 equal 1m x 1m squares.
  • Use a random number generator to randomly select a single square.
  • Take a 1m x 1m quadrat and place it in the selected square.
  • Count the number of clover in the square. - Repeat with a different square 4 times, and average the 5 results.
  • Multiply the average by 100 to estimate the number of clover in the field.
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25
Q

Name some Positive human interactions with ecosystems

A

Maintaining rainforests, ensuring habitats here are not destroyed.

Raising awareness among the public about how to protect ecosystems - e.g through large scale community projects

Reducing pollution and monitoring changes over time.

Reserving areas of scientific interest by stopping humans from going there.

Replanting hedgerows and woodlands to provide habitats which were previously destroyed

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26
Q

Name some Negative human interactions with ecosystems

A

Production of greenhouse gases leading to global warming.

Introducing non-indigenous species into the environment, which prey on native species.

Producing sulfur dioxide in factories which leads to acid rain – affects habitats.

stopping humans from going there.
Chemicals used in farming leak into the environment - if they leak into a lake, this can cause ​eutrophication - ​excessive growth of plant life which can deplete the body of water of oxygen (making it less able to sustain other species such as fish)

Clearing land in order to build on, reducing the number of habitats

Overfishing ​which reduces biodiversity and can lead to endangerment of some species

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27
Q

What measures have been put in place to maintain biodiversity?

A
  1. Breeding programs: to stop endangered species from becoming extinct.
  2. Protection of rare habitats: to stop the species here from becoming extinct, if damaged they may even be regenerated to encourage populations to live here
  3. Reintroduction of hedgerows and field margins around land where only one type of crop is grown: maintains biodiversity as the hedgerows provide a habitat for lots of organisms (because a field of one crop would not be able to support many organisms) and field margins provide areas where wild flowers and grasses can grow.
  4. Reduction of deforestation and carbon dioxide production: reduces the rate of global warming, slowing down the rate that habitats are destroyed
  5. Recycling rather than dumping waste in landfill: reduce the amount of land taken up for landfills, and slows the rate we are using up natural resources.
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28
Q

Explain the stages of the carbon cycle

A

● CO​2 ​is REMOVED from the air in photosynthesis by green plants and algae – they use the carbon to make carbohydrates, proteins and fats. They are eaten and the carbon moves up the food chain.
● CO​2 ​is RETURNED to the air when plants, algae and animals respire. Decomposers (a group of microorganisms that break down dead organisms and waste) respire while they return mineral ions to the soil.
● CO​2 ​is RETURNED to the air when wood and fossil fuels are burnt (called combustion) as they contain carbon from photosynthesis.

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29
Q

Explain stages of the water cycle?

A

● The sun’s energy causes water to evaporate from the sea and lakes, forming water vapour.
● Water vapour is also formed as a result of transpiration in plants.
● Water vapour rises and then condenses to form clouds. ● Water is returned to the land by precipitation (rain, snow or hail), and this runs into lakes to provide water for plants and animals.
● This then runs into seas and the cycle begins again.
● In areas of drought, we can harness the water cycle to produce ​potable ​(drinkable) water. For example, ​desalination​ is the process by which we remove salt and other minerals/impurities from seawater to make it drinkable. It is performed by a process called ​reverse osmosis ​and generally occurs on a large scale.

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30
Q

Nitrates

A

● Nitrogen gas in the atmosphere is too unreactive so cannot be used directly by plants.
● Nitrogen-fixing bacteria present in the root nodules of legume plants convert nitrogen gas into nitrates that can be used for growth.
● Lightning ​can convert nitrogen gas into nitrates
● The ​Haber process ​converts the hydrogen gas into ammonia.
● Plants ​absorb nitrates​ through the roots by active transport.

31
Q

Define population

A

All organisms of the same species living

with one another in a habitat

32
Q

Define community

A

All of the populations of different species

living together in a habitat

33
Q

Organisms within a community are
described as being ‘interdependent’.
What does this mean?

A

● Organisms are dependent upon each other.
● A change in the population of one species can
affect other populations within a community

34
Q

Give some examples of interdependence in a

community

A

● Plants depend on pollinators e.g. bees
● Herbivores are dependent on plants
● Animals are dependent on mates

35
Q

Describe how communities are affected by

environmental conditions

A

● Environmental conditions (e.g. temperature, light intensity,
water availability) affect the abundance and distribution of
organisms within communities
● e.g light intensity affects the rate of photosynthesis in producers
which serve as a source of food and shelter for other organisms

36
Q

Describe how communities are affected by pollutants

A

● Toxic chemicals (e.g. pesticides) bioaccumulate in food chains to
deadly concentrations at higher trophic levels, killing tertiary and
quaternary consumers
● Fertilisers that contaminate water sources can cause
eutrophication, killing multiple populations within a community
● Air pollution can affect the ability of some plant species to survive

37
Q

Describe how competition affects communities

A

● The presence of competitors affects population distribution
and size
● If one species is better adapted to survive in a certain
environment, it will outcompete other species, causing
their populations to decline

38
Q

Describe how predation affects communities

A

● Predation affects prey populations within a community
● e.g. if the number of predators decreases, the number of
prey will increase as fewer are killed
● Populations of all other organisms within the food chain will also be affected

39
Q

What piece of apparatus is used to measure the

abundance and distribution of organisms in an area?

A

A Quadrat

40
Q

What piece of apparatus is used to study the

distribution of organisms across a gradient?

A

A Belt Transect

41
Q

What is biodiversity?

A

he variety of living organisms in an

ecosystem

42
Q

How does fish farming impact biodiversity?

A

● Food used to feed the fish and waste can leak into water
sources, causing eutrophication
● Parasites from fish farms may spread and contaminate
surrounding ecosystems
● Other organisms may become tangled in netting

43
Q

How does the use of fertilisers affect biodiversity?

A

Excess fertiliser can wash into water
sources causing eutrophication and death
of many species. This reduces biodiversity.

44
Q

Describe how fertilisers can cause eutrophication

A
  1. Fertiliser run-off into rivers and lakes
  2. Nutrients build-up in water
  3. Algal bloom blocks sunlight
  4. Aquatic plants cannot photosynthesise ∴ less oxygen produced
  5. They die and decompose
  6. Decomposers further deplete oxygen levels
  7. Animals can no longer respire aerobically so die.
45
Q

How does the introduction of
non-indigenous species affect
biodiversity?

A

● They may out-compete native species, causing a reduction in
population numbers
● Native species may become the prey of non-indigenous
species
● They may bring new diseases which could kill large numbers of
native species, reducing biodiversity

46
Q

How can humans more positively impact

biodiversity?

A

● Protection of endangered species e.g. making hunting illegal,
breeding programmes increase population sizes
● Conservation schemes e.g. national parks, seed banks, zoos
● Reforestation
● Sustainable farming e.g. fewer pesticides
● Minimising global greenhouse gas production

47
Q

What is reforestation?

A

The Replanting of trees to help restore biodiversity.

48
Q

How do conservation schemes protect biodiversity?

A

They prevent species from becoming
extinct and increase population numbers,
maintaining biodiversity.

49
Q

Outline the benefits of maintaining biodiversity.

A

● Ensures future food requirements can be met, reduces damage to food chains
● Increases the likelihood of species adapting to future environmental change
● Many plant species are yet to be discovered and may contain chemicals that
could be used in future medicines
● Safeguarding valuable future resources e.g. fuels, paper
● Aesthetics - culture, ecotourism etc.
● Jobs provided by ecotourism, reforestation and conservation schemes

50
Q

What are the three types of nutrient cycle?

A

● Carbon cycle
● Water cycle
● Nitrogen cycle

51
Q

Why are the nutrient cycles important?

A

● Carbon, water and nitrogen are essential to life
● There is a fixed amount of nutrients on Earth
which must be constantly recycled

52
Q

Describe how materials cycle through the living and

non-living components of an ecosystem

A

● Organisms take in elements from their surroundings e.g. soil, air
● Elements converted to complex molecules which become biomass
● Elements transferred along food chains
● Elements returned to environment during excretion and
decomposition of dead organisms

53
Q

Describe the stages of the carbon cycle

A
  1. Photosynthesising plants remove CO2
    from the atmosphere
  2. Eating passes carbon compounds along a food chain
  3. Respiration in plants and animals returns CO2
    to the atmosphere
  4. Organisms die and decompose. Decomposers (bacteria and fungi)
    break down dead material and release CO2
    via respiration
  5. Combustion of materials (e.g. wood, fossil fuels) releases CO2
54
Q

Describe the stages of the water cycle

A
  1. Energy from the sun evaporates water from sources such as lakes and
    oceans. Transpiration also releases water vapour.
  2. Water vapour rises, cools and condenses forming clouds
  3. Precipitation occurs
  4. Water is absorbed by the soil and taken up by roots. Some is used in
    photosynthesis or becomes part of the plant, entering the food chain.
  5. Excretion returns water to the soil
  6. Surface runoff returns to streams, rivers and eventually the sea
55
Q

What is potable water?

A

Drinking water

56
Q

How can potable water be prepared?

A

Desalination

57
Q

What is desalination?

A

A process that removes salts from saline

water

58
Q

Name two methods of desalination

A

● Thermal desalination

● Reverse osmosis

59
Q

Describe thermal desalination

A

Salt water is boiled. Water evaporates,
rises and condenses down a pipe. This
separates pure water from salts.

60
Q

Describe reverse osmosis

A

● Saline water pumped into a vessel containing a partially permeable
membrane at high pressure
● High pressure forces water molecules to move from an area of low
water concentration (high salt concentration) to an area of high water
concentration (low salt concentration)
● Pure water separated from salts

61
Q

What do plants use to make proteins?

A

Nitrates

62
Q

Why can’t nitrogen be used directly by plants to form

proteins?

A

Nitrogen is unreactive

63
Q

Name the four types of bacteria involved in the

nitrogen cycle

A

● Decomposers
● Nitrogen-fixing bacteria
● Nitrifying bacteria
● Denitrifying bacteria

64
Q

What is the role of decomposers in the nitrogen

cycle?

A

● Break down proteins and urea into ammonia
● Ammonia dissolves in solution forming
ammonium ions

65
Q

What is the role of nitrogen-fixing bacteria in the

nitrogen cycle?

A

● Convert nitrogen gas into ammonia
● Ammonia dissolves in solution forming
ammonium ions

66
Q

Where are nitrogen-fixing bacteria found?

A

● Soil

● Root nodules of legumes

67
Q

What type of relationship is exhibited between

nitrogen-fixing bacteria and legumes?

A

● Mutualistic relationship
● Plants receive ammonium ions from bacteria
● Bacteria gain sugars from the plant

68
Q

What is the role of nitrifying bacteria in the nitrogen

cycle?

A

● Convert ammonium ions into nitrites

● Convert nitrites into nitrates

69
Q

What is the role of denitrifying bacteria in the

nitrogen cycle?

A

Convert nitrates into nitrogen gas

70
Q

Where are denitrifying bacteria commonly found?

A

Waterlogged soils

71
Q

Describe the stages of the nitrogen cycle

A
  1. Lighting and nitrogen-fixing bacteria convert nitrogen gas to ammonia
    which dissolves to form ammonium ions
  2. Nitrifying bacteria convert ammonium ions to nitrate ions which are taken up
    by plants and used to build proteins
  3. Feeding passes nitrogen through the food chain
  4. Organisms die and decompose. Decomposers break down proteins and urea
    to form ammonia which dissolves to form ammonium ions
  5. Denitrifying bacteria convert nitrates in the soil back to nitrogen gas
72
Q

How can the amount of nitrates in the soil be

increased?

A

● Using fertilisers e.g. animal manure, compost, artificial
fertilisers
● Crop rotation replenishes nitrates that may have been
depleted by the previous crop e.g. planting a
nitrogen-fixing crop

73
Q

What is meant by decomposition?

A

The breakdown of dead materials into

simpler organic matter

74
Q

How do decomposers break down dead matter?

A

Decomposers release enzymes which
catalyse the breakdown of dead material
into smaller molecules.

Biology yr11 (5 decks)

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