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HCHS GCSE Science 3 - Biology > Section 9 - Ecosystems and Material Cycles > Flashcards

Section 9 - Ecosystems and Material Cycles Flashcards

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1
Q

What are the four different levels of organisation in an ecosystem?

A

Individual, population, community, ecosystem.

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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 habitat?

A

The location in which the organism lives.

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5
Q

What is a community?

A

All the organisms of different species living in a habitat.

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6
Q

What is an ecosystem?

A

A community of organisms as well as the non-living conditions in the habitat.

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7
Q

What is another name for non-living conditions in a habitat?

A

Abiotic factors.

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8
Q

What does it mean if organisms are interdependent? What does this mean if a species population was to change?

A

The organisms depend on each other for things like food and shelter in order to survive and reproduce. Changes in one species population would have knock-on effects for other species in the same community.

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9
Q

What is mutualism?

A

A relationship between two organisms in which both organisms benefit.

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10
Q

Describe an example of mutualism.

A

Bees and flowering plants have a mutualistic relationship, the bees get nectar, to make food, from the plants, which transfer pollen onto the bees. The bees spread this pollen to other flowers that they visit which helps plants to reproduce.

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11
Q

What is parasitism?

A

A relationship between two organisms in which one benefits at the other’s expense, the parasite usually lives in or on the host, taking what it needs to survive but offering nothing in return.

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12
Q

Give an example of a parasitic relationship.

A

Fleas and mammals have a parasitic relationship, the flea feeds on the host’s blood, but the host receives nothing in return.

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13
Q

What are some abiotic factors?

A

Temperature, amount of water, light intensity, levels of pollutants.

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14
Q

What are some biotic factors?

A

Competition and predation.

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15
Q

How does temperature affect communities?

A

It changes species distribution and population size, e.g; rising temperatures have affected the distribution of bird species in Europe, an example of this is the European Bee-Eater Bird is normally a Mediterranean bird but is now found in parts of Germany.

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16
Q

How does the amount of water affect communities?

A

It changes species distribution and population size, e.g; daisies grow best in slightly damp soil if the soil becomes too dry or waterlogged the daisy population will decrease.

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17
Q

How does light intensity affect communities?

A

It changes species distribution and population size, e.g; grasses cannot grow well in shaded areas, so they may die off, they would likely be replaced by fungi which can cope better in the lower light levels.

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18
Q

How do the levels of pollutants affect communities?

A

They change species distribution and population size, e.g; lichen are unable to survive in areas where the concentration of the air pollutant sulfur dioxide are too high.

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19
Q

How does competition affect communities?

A

It changes species distribution and population size, e.g; red and grey squirrels live in the same habitats and eat the same food, grey squirrels are better able to compete with the reds and as a result, the red squirrel population has been decreasing.

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20
Q

How does predation affect communities?

A

It changes species distribution and population size, e.g; if the number of a predator species decreases, their prey’s populations may grow, since less of them are eaten by the predators.

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21
Q

What is competition?

A

Where organisms compete with other species as well as members of their own species for the same resources, including food, water, shelter, light and to breed.

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22
Q

What is predation?

A

Where organisms kill and eat other organisms to survive.

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23
Q

What is a quadrat?

A

A square frame enclosing a known area, to compare how common an organism is in multiple sample areas.

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24
Q

How are quadrats used to compare multiple sample areas?

A

1) Place a quadrat down on the ground at a random point within the first sample area.
2) Count all the organisms you’re interested in within the quadrat.
3) Repeat steps 1 and 2 lots of times.
4) Work out the mean number of target organisms per quadrat for the first sample area.
5) Repeat steps 1 to 4 for each other sample area.
6) Compare the means of each area.

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25
Q

How can quadrats be used to estimate a population size from a small sample area?

A

1) Place a quadrat down on the ground at a random location within the sample area.
2) Count all the organisms you’re interested in within the quadrat.
3) Repeat steps 1 and 2 lots of times.
4) Work out the mean number of target organisms per quadrat for the sample area.
5) Convert this to organisms per square meter.
6) Multiply the mean by the total area of the habitat.

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26
Q

What is the name given to how the abiotic factors change across a habitat?

A

A gradient.

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27
Q

How can quadrats be used to measure the distribution of organisms along a gradient? What is this called?

A

1) Mark out a line in the area you want to study.
2) Collect data along the line using quadrats placed either next to one another or at regular intervals, by counting the number of the target organisms per quadrat or estimate the percentage cover. Other information could be recorded, including information about the organisms or the abiotic factors of the quadrat.
3) Repeat steps 1 & 2 several times for quadrats next to them.
4) Produce means for each quadrat
5) Produce a graph to visually represent any correlation between the changing abiotic factor and the distribution of the target species.

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28
Q

What is the largest energy source for life on earth?

A

The sun.

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29
Q

How is most energy introduced to the food chain?

A

Plants convert small amounts of the light energy from the sun into glucose, some of which they use immediately in respiration, and some they store as biomass.

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30
Q

How does energy move through a food chain?

A

Animals eat plants, it uses some of this energy in respiration, some stored as biomass and some is lost through not being digested and instead excreted- but this is used to feed other organisms like bacteria and insects.

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31
Q

What is the name for a stage in a food chain?

A

A trophic level.

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32
Q

What are the main ways energy is lost from a food chain?

A

Respiration, a lot of energy produced from this is lost as heat and in movement.
Carcasses and bones, where not all of an organism is eaten.
Undigested material, such as faeces and in urine.

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33
Q

Why do few food chains exceed five trophic levels?

A

So much energy is lost through the previous levels that there wouldn’t be enough energy to support organisms past four or five trophic levels.

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34
Q

Why are there often fewer organisms at each higher trophic level? Why might this not be the case for some organisms?

A

There is less energy to support each level, so fewer organisms are born. This is often not the case for parasites, where many can feed off of one host, or bacteria and other monocellular organisms where thousands- if not billions can feed off of one organism.

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35
Q

What are pyramids of biomass? What do they show?

A

Visual representations for the transfer of biomass at each trophic level in a food chain, each level shows the combined weight of the organisms at each level of the food chain.

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36
Q

What is the name given to the first trophic level in a food chain? Why?

A

The producer, because they create biomass from energy and chemical reactions.

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37
Q

What are the names given to the trophic levels after the producer? Why?

A

The primary consumer, secondary consumer, tertiary consumer and so on, because they consume the lower trophic level’s biomass.

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38
Q

What gives most pyramids of biomass their pyramid shape?

A

Energy is lost as it is transferred up the food chain, so the upper levels have less biomass.

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39
Q

How can the energy lost and the efficiency of the energy transferred at each level be calculated? How could the equivalent be calculated for biomass?

A 
EL=EA-ET
EF=ET÷EA
EL = Energy Lost
EF = Efficiency
EA = Energy Available at Previous Level
ET = Energy Transferred to Next Level
To use these equations for biomass, change the energy to biomass so EL becomes biomass lost, EA becomes biomass available at previous level and ET becomes Energy Transferred to next level.
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40
Q

What is biodiversity?

A

The variety of living organisms in an ecosystem.

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41
Q

How does our use of industrial fertilisers affect biodiversity?

A

Nitrates are used in fertilisers to help plants grow, if too much is used and it rains, these nitrates end up in nearby lakes or rivers. This causes eutrophication, which allows algae on the water’s surface to grow rapidly, blocking out the light, plants under the water cannot photosynthesise and start to die and decompose. Microorganisms that feed on decomposing plants increase in population and use up the oxygen in the water killing off the remaining organisms that rely on oxygen for aerobic respiration, e.g. fish. This decreases biodiversity.

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42
Q

What is eutrophication?

A

An excess of nutrient in water.

43
Q

How is industrial fish farming in nets and tanks affecting biodiversity?

A

Any of;
Fish farming takes place in open water, such as lakes and oceans. Food is added to the nets in order to feed the fish, who produce large amounts of waste, some of this food and the waste can leak out into the open water, this causes eutrophication, which kills of wild species.
The farms also act as a breeding ground for parasites, which can escape net farms and kill off large quantities of wild fish.
Predators can become trapped in the nets and die.
Farmed fish may escape net farms which causes problems for wild populations of indigenous species.
Fish farmed in tanks are low on biodiversity because normally only one species is farmed at a time and they are kept free of any plants or predators, parasites and microorganisms are normally killed. But tank farms don’t affect local biodiversity.

44
Q

How can the introduction of non-indigenous species reduce biodiversity?

A

They may be better at competing for resources, like food and shelter, than the local species, which starve and possibly die out.
They may also bring new diseases, which the local species cannot survive, which kills off a lot of indigenous species.
Both of these examples reduce biodiversity.

45
Q

How is humanity attempting to maintain and increase biodiversity?

A

Reforestation and conservation.

46
Q

What is reforestation? How does it maintain and increase biodiversity?

A

Reforestation is when land where a forest previously stood is replanted to form a new forest. Forests have high biodiversity from the wide variety of trees and plants as well as the different species they provide food and shelter to, during deforestation this biodiversity is reduced but reforestation can restore it.
Reforestation is carefully planned to maximise the possitive effects, a higher variety of tree species results in better biodiversity than a single species would.

47
Q

What is conservation? How does it maintain and increase biodiversity? What methods are used for this?

A

Conservation is the protection of an endangered species.
It can raise the population of an endangered species, raising biodiversity in areas where the species disappeared.
This is done through various methods including;
Protecting the species habitat so that individuals have a place to live
Protecting the species in safe areas outside of their natural habitat, like zoos, and introducing captive breeding programs to increase their population size
The use of seed banks to store and distribute the seeds of rare and endangered plant species.

48
Q

What are the benefits of maintaining biodiversity? How?

A

Any from;
Protecting the human food supply, so future generations have food to eat.
Ensuring minimal damage to the food chains, if one species becomes extinct, the others that feed on it may suffer too.
Providing future medicines, many modern medicines are extracted from plants, if plants containing undiscovered medicinal chemicals become extinct we may miss out on powerful medicines.
Protecting cultures, different species are important to the cultural identity of various countries, like the USA’s bald eagle.
Ecotourism, people may be drawn to visiting unspoilt beautiful landscapes, which brings important income to some of the worlds poorer countries.
Providing jobs, ecotourism markets, conservation schemes and reforestation efforts provide jobs for local communities.

49
Q

What is food security?

A

Where a person has access to sufficient food that is safe to eat with the right nutritional balance.

50
Q

What are some biological factors affecting the level of food security?

A

Increasing human population, increasing meat and fish consumption- and subsequent increases in animal farming, environmental changes caused by human activity, sustainability as well as new pests and pathogens.

51
Q

How does the increasing human population affect food security?

A

The increase in population means that there are more people to feed, which risks food security unless more food is being produced in order to keep up with the rising demand.

52
Q

How does the increasing consumption of meat and fish, and the increase in animal farming as a result, affect food security?

A

Wealthier people can afford a wider variety of foods, including more meat and fish. There is less energy and biomass every trophic level you move up in a food chain, so for a given area of land, it is possible to produce more food for humans by growing crops rather than raising grazing animals or fish, which are often fed crops that would otherwise go to humans.
Plus, overfishing wild fish risks there not being enough available to catch in the future.

53
Q

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

A

Burning fossil fuels releases carbon dioxide, which naturally traps energy in the atmosphere, which keeps the earth’s surface warm. However, the increasing levels of carbon dioxide is causing temperatures to rise. Global warming has knock-on effects, such as changing rainfall patterns, which may affect the growth of crops and reduce yields.
The use of chemicals in farming and industry is also causing soil pollution which may also reduce our ability to grow crops.

54
Q

What is sustainability?

A

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

55
Q

How does sustainability affect food security?

A

The increasing production of renewable fuels from crops lessens the need for non-renewable fossil fuels like diesel and petrol, however, this uses crops that could feed humans, the need for fuels and the need for more food must be balanced at some point.
The high input costs of farming may make it too expensive for farmers in some areas to continue farming and maintain future food production.

56
Q

How do new pests and pathogens affect food security?

A

New pests and pathogens can damage crops and livestock which can negatively impact on yields since much of the population may not be resistant to the disease, and will be damaged as a result.

57
Q

What is the carbon cycle?

A

How carbon is naturally recycled within an ecosystem.

58
Q

How are materials transported through ecosystems?

A

Living things are made from elements taken from the environment, the elements form complex structures which form the organisms. Elements are passed along food chains when animals eat plants and each other. Elements are recycled, waste products and dead organisms are broken down by microorganisms which return the elements to the soil or air, ready to be taken in by new plants and returned to the food chain.

59
Q

Where is the source for all carbon in nature, how is it introduced into the carbon cycle?

A

Almost all carbon in the carbon cycle comes from carbon dioxide in the air, which plants use in photosynthesis to produce glucose and other carbon compounds afterwards.

60
Q

How does carbon enter animals in the carbon cycle?

A

When animals eat plants and each other.

61
Q

How does carbon enter human products in the carbon cycle?

A

When humans make products out of plants and animals, such as clothing.

62
Q

How does carbon enter the soil in the carbon cycle?

A

When animals produce waste or die.

63
Q

How does carbon enter fossil fuels in the carbon cycle?

A

Animal and plant matter decay under the ground to produce combustible carbon compounds.

64
Q

How does carbon re-enter the atmosphere in the carbon cycle?

A

As carbon dioxide from respiration from plants and animals, decay from decomposers in the soil, the combustion of fossil fuels and products made from plants and animals.

65
Q

Describe the water cycle.

A

Energy from the sun causes water to evaporate from the land and sea, turning it into water vapour, as well as plants in transpiration.
This vapour is carried upwards where it cools and condenses to form clouds.
Water falls from the clouds as precipitation onto the land providing fresh water for plants and animals, or back into the sea.
The land water drains into the sea and the cycle continues.

66
Q

What is a drought?

A

A lack of precipitation.

67
Q

What is precipitation?

A

How water falls from the clouds, normally as rain, but can be snow or hail.

68
Q

What are some problems caused by droughts?

A

Drinking water may become inaccessible and plants may dry out and die.

69
Q

What is potable water?

A

Water that is both safe and suitable for drinking.

70
Q

What is desalination?

A

The production of potable water by removing the salts, mineral ions, from salt water, such as sea water.

71
Q

What are the two main methods of desalination?

A

Thermal desalination and reverse osmosis.

72
Q

How does thermal desalination work?

A

Salt water is boiled in a large enclosed vessel, the water evaporates, the steam rises to the top of the vessel leaving the salts behind, the steam is then piped out from the top to a separate vessel where it condenses as pure potable water.

73
Q

How does reverse osmosis work?

A

Salt water is treated to remove solids, it is then fed at high pressure into a vessel containing a partially permeable membrane. The pressure causes the water molecules to move across the membrane in the opposite direction to standard osmosis, leaving the lats behind producing potable water.

74
Q

How much of the atmosphere is nitrogen gas? What is the chemical symbol for this?

A

78% N₂

75
Q

Why nitrogen not able to be used directly by plants and animals?

A

It is very unreactive so it is difficult to use as it is.

76
Q

What is nitrogen used for in living organisms?

A

To make proteins used for growth.

77
Q

How does nitrogen enter the soil from the atmosphere?

A

Lightning causes N₂ to react with oxygen, which produces nitrates, which enters the soil.
Nitrogen-fixing bacteria in the soil turn N₂ into ammonia which forms ammonium ions in solution, which plants use.

78
Q

How does nitrogen enter the soil from plants and animals?

A

Decomposers turn proteins and urea, animal waste, into ammonia, which forms ammonium ions in solution, which plants use.
Nitrifying bacteria turn ammonia in decaying matter into nitrites, and other species of nitrifying bacteria turn nitrites into nitrates.

79
Q

How does nitrogen enter plants?

A

Nitrate and ammonium ions absorbed by the roots from the soil.
Nitrogen-fixing bacteria in the roots turn N₂ from the air into ammonia, which forms ammonium ions in solution, which plants use.

80
Q

How does nitrogen enter animals

A

Eating plants and each other.

81
Q

How does nitrogen re-enter the atmosphere?

A

Denitrifying bacteria in the soil turn nitrates back into N₂ gas.

82
Q

Which plants can have nitrogen-fixing bacteria in their roots? Why? What is the name for this type of relationship?

A

Legume plants, because their roots contain nodules which house the bacteria, this is an example of a mutualistic relationship.

83
Q

Why must farmers introduce nitrates into their soil?

A

Plants take of nitrates as they grow, but since they are harvested and do not decay normally, the nitrates are not returned to the soil, so more must be added.

84
Q

What happens to plants that don’t get enough nitrates?

A

Deficiency diseases and poor growth.

85
Q

What methods do farmers use to reintroduce nitrates to their soil?

A

Crop rotation and fertilisers.

86
Q

What is crop rotation? How does it increase the number of nitrates in the soil?

A

Different crops are grown in a field each year in a cycle, so every few years a legume is grown, and the nitrogen-fixing bacteria introduce more nitrates into the soil.

87
Q

What are fertilisers? How do they increase the number of nitrates in the soil?

A

Fertilisers are substances containing nitrates and other mineral ions needed by the plants, which make the soil more effective for growing crops, this introduces more nitrates into the soil. Examples include manure and other animal wastes, artificial fertilisers are also available and sometimes more effective but very expensive.

88
Q

What are indicator species?

A

Species that are very sensitive to changes in their environment, they can be studied to indicate changes in the environment which could cause major problems for other organisms.

89
Q

How are indicator species used to measure water pollution?

A

Stonefly larvae and freshwater shrimps are very sensitive to the levels of oxygen dissolved in the water, stonefly larvae indicate that the water is very clean.
Bloodworms or sludgeworms indicate high levels of water pollution.

90
Q

How are indicator species used to measure air pollution?

A

Particular species of lichen are sensitive to the concentrations of sulfur dioxide, which is released from car exhausts, power stations and more, bushy lichen requires cleaner air, whereas crusty lichen can survive in higher sulfur dioxide concentrations.
Blackspot fungus is found on rose leaves, it is also sensitive to sulfur dioxide, its presence indicates cleaner air.

91
Q

What are the two ways of using indicator species to measure pollution?

A

A simple survey of whether a species is present or not in an area, which is a quick method of discerning whether the area is polluted or not.
Measuring how common indicator species are in an area, which gives a numerical value which can compare roughly how polluted an area is in comparison to another.

92
Q

What are the benefits of using indicator species?

A

It is simple and cost effective.

93
Q

What are the drawbacks of using indicator species?

A

They are not accurate, and cannot account for factors other than pollution.

94
Q

What are some examples of non-living indicators?

A

Dissolved oxygen meters and chemical tests, electronic meters and laboratory tests.

95
Q

How are dissolved oxygen meters and chemical tests used to identify levels of water pollution?

A

They can be used to accurately measure the concentrations of oxygen in the water to show how the level of water pollution changes.

96
Q

How are electronic meters and laboratory tests used to identify levels of air pollution?

A

They can be used to accurately measure the concentrations of sulfur dioxide in the air to show how the levels of air pollution changes.

97
Q

What causes decomposition?

A

Microorganisms, such as soil bacteria and fungi.

98
Q

What is the rate of decay?

A

How fast something decomposes.

99
Q

How does temperature affect the rate of decay? Why?

A

Warmer temperatures speed up the rate of decay, because it is a chemical reaction, however, the enzymes used in decomposition denature if the temperature gets too high, halting the reaction.

100
Q

How does water content affect the rate of decay? Why?

A

Decay takes place faster in moist environments because the organisms need water to survive and carry out their biological processes.

101
Q

How does oxygen availability affect the rate of decay? Why?

A

Decomposition happens faster in environments where there is plenty of oxygen available, this is because many of the organisms require oxygen for aerobic respiration in order to decompose dead matter, those that don’t require oxygen usually work slower anyway.

102
Q

How does food preservation work?

A

By slowing decomposition by making the environment less suitable for decomposers.

103
Q

List examples of preservation methods. How do they work?

A

Fridges and freezers, they lower the temperature, slowing the decomposers’ rates of decay and reproduction, or stops it if the food is frozen.
Sterilised, airtight cans, stops the microorganisms getting in, and kill any that get in during the production, any that survive are slowed or killed by the lack of oxygen.
Drying, removes water from the food so the microorganisms can’t survive and reproduce, as does adding salts or sugars which causes the microorganisms to lose water by osmosis.

HCHS GCSE Science 3 - Biology (9 decks)

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