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Biology F215 > Ecosystems And Sustainability > Flashcards

Ecosystems And Sustainability Flashcards

0
Q

What is a habitat?

A

The place where an organism lives

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1
Q

What is an ecosystem?

A

Any group of living organisms and non living things occurring together, and the interrelationships between them

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2
Q

What is a population?

A

All of the organisms of one species that live in the same place at the same time, and that can breed together

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3
Q

What is a community?

A

All of the populations of different species that live in the same place at the same time, and can interact with each other

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4
Q

What is the name for the role that each species plays in an ecosystem?

A

A niche

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5
Q

Why is it almost impossible to entirely define an organism’s niche?

A

Because each organism interacts with both living and non-living things in its environment, so there are a lot of variables which may not always be constant

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6
Q

Examples of biotic factors that affect an organism

A

Food supply, predation and disease.

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7
Q

Examples of abiotic factors that affect an organism?

A

Temperature, soil type, pH

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8
Q

What are biotic factors? Examples?

A

The living features of an ecosystem e.g. food supply, predation, disease

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9
Q

What are abiotic factors? Examples?

A

The non living features of an ecosystem, e.g. pH, temperature, soil type

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10
Q

How do ecosystems change?

A

The community of living things in an ecosystem interact with each other and with their physical environment, and any small change in one population can greatly affect the others, meaning population sizes constantly rise and fall.

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11
Q

How does matter move through an ecosystem?

A

It is constantly recycled within an ecosystem, as seen in nutrient cycles such as the nitrogen cycle and the carbon cycle.

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12
Q

How does energy move through an ecosystem?

A

It flows through the ecosystem from the producers to the consumers, with energy being lost to the environment at each level

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13
Q

What is a producer?

A

An organism that produces organic molecules using sunlight energy

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14
Q

What is a primary consumer and what is a secondary consumer?

A

Primary consumers are herbivores who feed on plants, secondary consumers are carnivores, who eat primary consumers. Secondary consumers can be eaten by tertiary consumers.

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15
Q

What is a decomposer?

A

An organism which feeds on waste material or dead organisms. Examples of decomposers include some bacteria, some fungi and some animals

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16
Q

What is a trophic level?

A

The stage in a food chain that is occupied by a particular group of organisms e.g. Producers are the first trophic level in a food chain

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17
Q

What is a food web?

A

Different food chains drawn together to show how energy flows through the whole ecosystem, as within an ecosystem living organisms are usually members of more than one food chain, and often feed at different trophic levels in different chains.

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18
Q

Why is energy lost from the food chain at each trophic level?

A

Living organisms need energy to carry out life processes. This energy is released from organic molecules by respiration. Some of the energy is eventually converted to heat, and is lost from the food chain.
Energy remains stored in dead organisms and waste material, which is then only available to decomposers. This includes the parts of animals and plants that cannot be digested by consumers

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19
Q

Why is not all energy from sunlight used by plants?

A
  • plants can’t use all the light energy that reaches their leaves as some is the wrong wavelength and is reflected, and some passes straight through the leaves.
  • some sunlight can’t be used as it hits parts of the plant that can’t photosynthesise, e.g. the bark of a tree.
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20
Q

Why can less living tissue be kept alive at higher trophic levels of a food chain?

A

Because there is less energy to sustain it, as the amount of energy decreases from one trophic level to the next.

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21
Q

How does biomass change between levels of a food chain?

A

It decreases with each subsequent trophic level.

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22
Q

What is a pyramid of numbers?

A

A pyramid with a bar for each trophic level in a food chain, with the producers at the bottom and consumers at the top. The area of each bar is proportional to the number of individuals it represents. Pyramids can be drawn for individual food chains or for an ecosystem as a whole.

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23
Q

Why is a pyramid of biomass better than a pyramid of numbers?

A

It provides a more accurate picture about how much living tissue exists at each level. In a pyramid of biomass the area of the bars is proportional to the amount of biomass at each level

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24
Q

What is biomass?

A

The dry mass of an organism. To calculate this properly an ecologist would put the organism in an oven until all water had been evaporated. However this would be quite destructive to the ecosystem being studied, so ecologists often just measure the wet mass and calculate the dry mass from previously published data.

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25
Q

What are pyramids of energy?

A

Pyramids in which the amount of calories released by burning organisms at each trophic level is recorded and is proportional to the area of each bar. This is quite destructive, so pyramids of biomass are usually used instead.

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26
Q

How can you work out the efficiency of energy transfer between two trophic levels?

A

By working out the percentage efficiency of energy transfer. To do this you divide the net productivity of one trophic level by the net productivity of the previous trophic level, and multiply it by 100

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27
Q

What is net productivity?

A

The energy available to a trophic level that becomes biomass, by being stored or used for growth. This is the amount of energy that is available to the next trophic level

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28
Q

How does the efficiency of energy transfer change as you move up a food chain?

A

Energy transfer generally becomes more efficient the higher up a food chain you go

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29
Q

Why is the transfer of energy from the sun to producers not very efficient?

A

Because not all of the light energy that plants receive can be absorbed, and some energy that is absorbed is lost during photosynthesis

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30
Q

Why is the energy transfer from a producer to a consumer less efficient than from a consumer to a secondary consumer?

A

Because plants contain a greater proportion of indigestible material than animals, such as cellulose. Animals contain a large proportion of relatively digestible meat.

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31
Q

What is a calorimeter?

A

A piece of equipment used to measure the amount of heat energy released when something is burnt.

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32
Q

What are two ways the efficiency of energy transfer in an organism can be measured?

A
  • using a calorimeter

* measuring the organism’s biomass

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33
Q

Why would farmers want to reduce the amount of energy lost from food chains?

A

To increase the productivity.

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34
Q

What farming methods are used to make the transfer of energy between trophic levels more efficient?

A

Herbicides are used to kill weeds that compete with agricultural crops for energy.
Fungicides kill fungal infections in crops, so the crops use less energy fighting infection and more for growth.
Insecticides kill insect pests that eat and damage crops, meaning less biomass is lost from the crops.
Natural predators can also be introduced to the ecosystem to eat the pests.
Fertilisers are added to the soil to ensure that the growth of plants is not limited by a lack of minerals, meaning energy from the ecosystem is not wasted.
Rearing livestock intensively, by keeping them warm and in small pens, so energy is not lost. They can also be given high energy food, and food that contains antibiotics.

35
Q

What is the nitrogen cycle?

A

The cycle of nitrogen between different organisms and the environment

36
Q

What do plants and animals need nitrogen for?

A

To make proteins and nucleic acids for growth

37
Q

What is the importance of bacteria in the nitrogen cycle?

A

The atmosphere is made up of about 78% nitrogen, but plants and animals can’t use it in that form: bacteria are needed to convert it into nitrogen compounds first

38
Q

What are the four different processes in the nitrogen cycle that involve bacteria?

A

Nitrogen fixation
Ammonification
Nitrification
Denitrification

39
Q

What is nitrogen fixation?

A

When nitrogen has in the atmosphere is converted to ammonia by bacteria called rhizobium. The ammonia can then be used by plants.

40
Q

Where are rhizobium bacteria found?

A

Inside the root nodules of leguminous plants. They have a mutualistic relationship with the plants, as they provide the plant with nitrogen compounds, and the plant provides them with carbohydrates

41
Q

What is ammonification?

A

When nitrogen compounds from dead organisms and animal waste are turned into ammonium compounds by decomposers.

42
Q

What is nitrification?

A

When ammonium compounds in the soil are changed to nitrogen compounds that can be used by plants. This process is completed by two different bacteria; nitrosomonas, which change ammonium compounds into nitrites, and nitrobacter, which change nitrites into nitrates.

43
Q

What is denitrification?

A

When nitrates in the soil are converted into nitrogen gas by denitrifying bacteria, which use nitrates to carry out respiration, producing nitrogen gas. This happens under anaerobic conditions, such as in waterlogged soils

44
Q

What bacteria are responsible for nitrogen fixation?

A

Rhizobium

45
Q

What bacteria are responsible for nitrification?

A

Nitrosomonas, which change ammonium compound to nitrites

Nitrobacter, which change nitrites to nitrates

46
Q

What does rhizobium bacteria do?

A

It is involved in nitrogen fixation, and converts nitrogen gas into ammonia, which can be used by plants

47
Q

What does nitrosomonas bacteria do?

A

It changes ammonium into nitrites

48
Q

What does nitrobacter bacteria do?

A

It changes nitrites into nitrates

49
Q

What other ways are there for nitrogen to enter an ecosystem other than from nitrogen fixation by bacteria?

A

By lightening, which causes fixation of atmospheric nitrogen

By the haber process, which is used to produce artificial fertilisers from atmospheric nitrogen

50
Q

What is succession?

A

The process by which an ecosystem changes over time

51
Q

How does succession happen?

A

In a series of stages, with the species in each stage slowly changing the environmental conditions in an area, making them more suitable for other species. This means that the biotic conditions change as the abiotic conditions change, causing one community of organisms to be replaced by another.

52
Q

What are the two main types of succession?

A

Primary succession and secondary succession

53
Q

What does succession end in?

A

A climax community

54
Q

What is primary succession?

A

Succession that starts on land that has been newly formed or exposed, such as after a volcanic eruption or drop in sea level. There is no soil or surface material to start with.

55
Q

How does primary succession happen?

A

Algae and lichens begin to live on the bare rock. This is called a pioneer community. The algae and lichen erode the rock and dead and rotting organisms build up. This produces enough soil for larger plants, like mosses and ferns, to grow. The mosses and ferns replace, or succeed, the algae and lichens. In a similar way the mosses and ferns are then replaced by larger plants such as grasses and small flowering plants. These are then replaced by shrubs, ferns and small trees, which outcompete the grasses and smaller plants to become the dominant species. These are then replaced by larger trees, as the soil is finally deep and rich enough to support them. They become the dominant species and the climax community is formed.

56
Q

Why do sand dunes display all of the stages of succession at once?

A

Because the se deposits sand on the beach, and the sand nearest to the sea is deposited more recently than the sand further away. This means that the further up the beach you go, the further through the stages of succession the ecosystem will be.

57
Q

Why do new stages of succession happen?

A

Because the plants and animals that are already in an ecosystem change the environment to make it more suitable for other, larger plants. These plants are better adapted for the improved conditions, so they out-compete the plants and animals already there and become the dominant species.

58
Q

As succession goes on how does the ecosystem change?

A

It becomes more complex and more diverse, as new species move in alongside existing species, and plants create more habitats for animals.

59
Q

What is a climax community?

A

The largest and most complex community of plants and animals an ecosystem can support. When an ecosystem reaches it’s climax community it won’t change much more as it is in a steady state.

60
Q

What is secondary succession?

A

Succession that happens on land that has been cleared of the plants, but where the soil remains, e.g. After a forest fire, or where a forest has been cut down by humans. The established community of species is usually destroyed, but without much disturbance to the soil. The process is similar to primary succession, but as there is already a soil later, it starts at a later stage, and the pioneer species are larger plants.

61
Q

How do abiotic factors affect population size?

A

They can limit the size of the population, as if there is not enough water, light or space in a habitat, fewer organisms will live there. When abiotic factors are ideal for a species, organisms can grow fast and reproduce successfully.

62
Q

What is inter specific competition?

A

Interspecific competition is when organisms of different species compete with each other for the same resources. This will mean that the resources available to both populations are reduced, e.g. If they share a food source, there will be less food for both of them. This means both populations will be limited by availability of food and both will have less energy for growth and reproduction. Therefore population sizes will be lower for both species.

63
Q

How can interspecific competition affect the distribution of species?

A

If two species are competing but one is better adapted to its surroundings the other is likely to be outcompeted, and will die out in that area.

64
Q

What is intraspecific competition?

A

Intraspecific competition is when organisms of the same species compete with each other for the same resources.

65
Q

What effect will intraspecific competition have on population size?

A

It can cause a cyclic change in population size, where the population grows and then shrinks and then grows again. This is because population size will increase when resources are plentiful, and as population size increases there will be more organisms competing for space and food. This causes these resources to become limiting, and population size begins to decline again. The smaller population means less competition, so population grows again.

66
Q

What does the term carrying capacity refer to?

A

The maximum stable population size of a species that an ecosystem can support.

67
Q

What is the relationship between the size of population of predators and the size of population of their prey?

A

As the size of population of prey increases, predators have more food so their population increases. This means more of the prey are eaten, so their population size decreases. This means there is less food for the predator and their population size decreases, so prey population increases.

68
Q

Why are predator prey relationships usually more complicated than the standard predator/prey population size graph?

A

Because there are other factors involved, such as availability of food for the prey and disease. Predators may also eat multiple types of prey.

69
Q

What is a limiting factor?

A

Something which stops the population size of a species increasing. These can be biotic or abiotic.

70
Q

What are the two things scientists look at when investigating populations of organisms in a particular area?

A

Abundance - the number of individuals of a species in a particular area
Distribution - where a particular species is within the area you’re investigating

71
Q

What is sampling?

A

Looking at the abundance and distribution of organisms in small areas within a larger area being investigated, in order to estimate the abundance and distribution in the larger area

72
Q

What things can be used to measure the abundance and distribution of organisms in an area?

A 
Frame quadrats
Point quadrats
Line transects 
Belt transects
Interrupted transects
73
Q

What are frame quadrats?

A

Frames divided into a grid which are placed on the ground at random points in the area being investigated and the percentage cover is worked out

74
Q

What are point quadrats?

A

A horizontal bar on two legs with a series of holes at set intervals along its length. Pins are dropped through the holes and if the pin touches a plant that plant is recorded

75
Q

What is a line transect?

A

A tape measure is placed along the transect and the species touching the transect are recorded.

76
Q

What is a belt transect?

A

Data is collected along the transect using frame quadrats placed next to each other

77
Q

What is an interrupted transect?

A

At regular points on the transect a point quadrat is placed at 90° to the transect

78
Q

What is conservation?

A

The protection and management of ecosystems so that the natural resources in them can be used without running out

79
Q

Why is conservation a dynamic process?

A

Conservation methods need to be adapted to the constant changes that occur within ecosystems, caused naturally and by humans.

80
Q

What are the economic reasons for conservation?

A

Ecosystems provide resources for lots of things that humans need such as drugs and food. These are economically important as they are traded both globally and locally. If the ecosystems aren’t conserved then the resources will be lost, so future trade will decrease

81
Q

What are social reasons for conservation?

A

Ecosystems bring joy to people because they are attractive to look at and are used for recreational activities, which will be lost if the ecosystems are not conserved

82
Q

What are ethical reasons for conserving ecosystems?

A

Some people think ecosystems should be conserved because it is the right thing to do. Especially if an ecosystem is at risk because of humans. Also people think we have a moral responsibility to conserve ecosystems for future generations.

83
Q

What are ecological reasons for conserving species?

A

Conserving species and habitats can help prevent climate change.
Conserving species and habitats also helps prevent the disruption of food chains. Disruption of food chains can have knock on effects on other organisms

84
Q

What is preservation?

A

The protection of ecosystems so they’re kept exactly as they are. Nothing is removed from a preserved ecosystem, and they can only be used for activities that don’t damage them.

85
Q

What effects have human activities had on the Galápagos Islands?

A

Early explorers of the Galapagos directly affected the populations of some animals by eating them.
Non native animals introduced to the island competed with or predated on native species e.g dogs eat the young giant tortoises
Non native plants introduced to the islands compete with native plant species, as they are taller than them, causing a decrease in their populations.
Fishing has caused a decrease in the populations of some of the sea life around the Galápagos Islands
A recent increase in tourism has lead to an increase in development on the islands, damaging the ecosystem
Increase in population on the island has also increased because of tourism. This could lead to further development and further damage

86
Q

How can ecosystems be managed in a sustainable way, with reference to temperate woodland?

A

For every tree that is cut down for timber a new one is planted in its place so that the forest never becomes depleted. This needs to be done carefully to be successful:
Trees cut down in strips or patches - woodland grows back more quickly in small areas between bits of woodland than in large exposed areas
The cleared areas aren’t too large, to prevent soil erosion
Trees can be cut down by coppicing, cutting down trees in a way that let’s them grow back, so new trees don’t need to be planted
Only native species are planted as they grow more successfully because they are adapted to the climate
Planted trees can be attached to posts to provide support, and are grown in plastic tubes that stop them being eaten by grazing animals, so they will survive to adulthood
Trees aren’t planted too close together so they don’t compete with each other for space or resources

Biology F215 (4 decks)

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