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Biology GCSE > Ecosystems and Material Cycles > Flashcards

Ecosystems and Material Cycles Flashcards

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1
Q

What is an organism?

A

A single living individual

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2
Q

What is a population?

A

All the organisms of the same species in an area

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3
Q

What is a community?

A

All the populations in an area

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4
Q

What is an ecosystem?

A

The community and the non-living components in an area, all organisms in an ecosytem depend on other organisms for food, shelter etc.

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5
Q

What factors effect distribution of living organisms?

A
  • Biotic factors (factors that involve living organisms) such as prey, competitors and predators
  • Abiotic factors (non-living factors) such as light, average temperature, average rainfall, oxygen levels in water, pollution
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6
Q

How can changes in abiotic factors be measured?

A

Using equipment such as a thermometer, oxygen meter etc.

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7
Q

What is a pollutant?

A

Energy or a chemical substance that has a harmful effect on living organisms

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8
Q

How do organisms deter predators?

A
  • Some animals show that they’re highly poisonous by displaying very bright colours
  • Some animals have frightening colours and patterns on them
  • Some plants have big thorns and other plants are poisonous
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9
Q

Why is there competition between organisms?

A

Organisms need a supply of materials from their surroundings and sometimes from other living organisms, some materials have limited supply, therefore there is competition between organisms

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10
Q

What kind of competition is there between plants?

A

Competition for light and space above ground, competition for water and nutrients underground

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11
Q

What kind of competition is there between animals?

A
  • Food
  • Mates for reproduction
  • Territory (space for feeding, reproduction etc)
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12
Q

What is parasitism?

A

Where a parasite feeds of a host when they’re living together, this harms the host but benefits the parasite

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13
Q

Give some examples of parasites

A
  • Fleas, they feed off other animals by sucking the animal’s blood after piercing its skin
  • Head lice, they feed off humans by sucking blood off a human head after piercing the skin
  • Tapeworms, they feed off other animals by living in the animal’s intestine and absorbing nutrients from the digested food in the intestine
  • Mistletoe, mistletoe grows roots into a tree to absorb water and nutrients from the host
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14
Q

What is mutualism?

A

When two organisms live closely together in a way that benefits them both

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15
Q

Give some examples of mutualists

A
  • Oxpeckers and herbivores such as deers, the bird benefits by getting food, the herbivore benefits from the loss of skin parasites
  • Larger fish such as a sharks and cleaner fish, the larger fish benefits from the loss of dead skin and parasites, the cleaner fish benefit by getting food
  • Nitrogen fixing bacteria and legume plant, the nitrogen fixing bacteria benefits as it is protected from the environment and gets food from the plant, the legume plant benefits by getting nitrogen compounds for healthy growth from the bacteria
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16
Q

How does sampling with quadrats work?

A
  • Quadrats are placed randomly in the area
  • The number of study organisms are counted in each area
  • The number of organisms in the whole area is estimated using the equation: number of organisms in the whole area = mean number of organisms in one quadrat x (total area / area of one quadrat)
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17
Q

What is a belt transect?

A

A transect line (for example, a tape measure) is placed along the ground, then quadrats are placed at regular intervals along the transect, belt transects are used to observe the effect of abiotic and biotic factors on the distribution of an organism. The changes in factors are also measured at each quadrat position, this makes it easier to link a change in distribution with a physical factor

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18
Q

Give some examples of when belt transects would be used

A
  • When there is a pond nearby to dry land

- When there’s a low tide on a rocky shore near to high tide

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19
Q

How do trophic levels work?

A
  • Energy is transferred to a plant by light during photosynthesis, most of that energy is stored in new plant biomass which can be transferred to herbivores in their food, however, some of the energy is transferred to surroundings as heat because of respiration
  • When this plant is eaten the biomass is transferred and stored as animal biomass, they have energy that is transferred to the surroundings as heat by respiration as well, they also have energy stored in faeces and urine
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20
Q

What are apex predators?

A

Carnivores with no predators

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21
Q

What are decomposers?

A

Things that break down waste products and dead remains to return mineral ions to the soil

22
Q

How do you calculate the biomass efficiency?

A

Efficiency = gain in biomass / total intake of biomass

23
Q

What is biomass measured in?

A

g/m^2

24
Q

Why does the amount of biomass at each trophic level decrease?

A

Because some energy at each level is transferred by heating the environment

25
Q

What is fish farming?

A

Where only one type of fish is grown in one area, the fish are fed and the waste they produce is removed from their tanks

26
Q

What are the disadvantages of fish farming?

A
  • The waste can pollute the local area, changing conditions so some local species die out
  • Diseases from the farmed fish can spread to wild fish and kill them
27
Q

What is the min advantage of fish farming?

A

It reduces fishing of wild fish

28
Q

What are non-indigenous species?

A

Organisms that are not found naturally in the area

29
Q

What are the disadvantages of non-indigenous species?

A
  • They might reproduce rapidly as they don’t have predators in the area
  • They might out-compete native species for food or other resources
30
Q

What is the main advantage of non-indigenous species?

A

They may provide food for native species

31
Q

What is the process of eutriphication?

A
  • Fertilisers are added to fields get and they get into streams and rivers, this adds phosphates and nitrates to
    the water
  • This causes water and plants water plants and algae to grow more quickly
  • Plants and algae cover the water surface and block the light to the deeper water
  • Deeper plants can’t get any light so they die
  • Bacteria decompose dying plants and take oxygen from the water
  • There is not enough oxygen left in the water for fish so they die
32
Q

What are the main reasons for maintaining biodiversity?

A
  • Moral reasons: humans should respect other organisms
  • Aesthetic reasons: people enjoy seeing the variety of living organisms living in different habitats
  • Ecosystem structure: some organisms play important roles in ecosystems, if this planet loses species food chains become more unstable
  • Usefulness: some species are particularly useful to humans, for example, plants that produce life saving drugs
33
Q

What is reforestation?

A

Replanting forests where they’ve been destroyed

34
Q

What are the advantages of reforestation?

A
  • Restores habitat for species
  • Reduces the concentration of carbon dioxide in the air as the trees photosynthesise
  • Tree roots bind the soil together and reduce the effects of soil erosion
  • Affect local climate for example reducing the range of temperature variation
35
Q

Describe the chain of events that occur due to increased food demand

A
  • Increasing human population means more food is needed
  • Increasing demand for meat and fish means more land is used for animal farming and there’s a greater impact on wild fish populations
  • Movement of people introduces new pests and pathogens to areas, damaging local crops and animals
  • Increased waste is waste is produced causing more pollution
36
Q

What are the main factors that could effect food security?

A
  • Birth rate in some countries is increasing
  • People’s tastes are changing in the UK meaning more food has to be imported, this effects the food security of the countries that are importing the food
  • Pests and pathogens
  • Environmental change
  • Increasing cost of fertilisers and pesticides
  • War
37
Q

Why may biofuels not be a sustainable alternative to fossil fuels?

A

They’re expensive meaning the poor may not be able to afford them

38
Q

Describe the process of the carbon cycle

A
  • Carbon dioxide is present in the atmosphere
  • This carbon dioxide is converted to carbon during photosynthesis of plants and algae, the carbon is converted carbohydrates, fats and proteins which make up the cells of the plants and algae
  • Some of the carbon returns back to the atmosphere as carbon dioxide through aerobic respiration
  • Carbon is then transferred to animals when they eat the plants and this carbon is transferred to other animals if they eat these animals
  • These animals respire and release some carbon as carbon dioxide into the atmosphere
  • Animals produce waste products and animals and plants eventually die, this means that carbon is stored in waste products and dead remains
  • These dead remains and waste products are broken down by decomposers, these decomposers respire and release carbon back into the atmosphere as carbon dioxide
  • Under some conditions decomposers don’t function properly so waste products are not broken down meaning carbon is stored underground as fossil fuels
  • Over the last 200 years humans have been burning large amounts of fossil fuels meaning a large amount of carbon dioxide is released into the atmosphere
39
Q

What is the role of a decomposer?

A

To cycle materials through an ecosystem, they also release mineral ions to the soil and return carbon back to the atmosphere as carbon dioxide

40
Q

Describe the process of the water cycle

A
  • Water is in the oceans
  • Energy from the sun causes the water to evaporate from the surface of the sea
  • The water vapour then travels into the air and cools down, when it cools the water vapour condenses to form clouds
  • The water in the clouds then falls to the ground as precipitation, precipitation includes rain, snow, hail and sleet , all forms of precipitation is fresh water
  • Once the water hits the ground, some of it simply evaporates back into the atmosphere as water vapour
  • Some of the water passes through rocks to form aquifers, a lot of the water forms rivers and streams, the water in rivers and streams eventually drains back into the sea
  • Water evaporates from plants when they transpire
  • Animals take in water through drinking and in their food, they release this in their faeces, urine and when they exhale
41
Q

Where is desalination used?

A

In countries that suffer drought, they don’t get enough precipitation to use as their source of potable source

42
Q

What is the problem with plants absorbing nitrogen and how is it naturally overcome?

A
  • Nitrogen is present in the atmosphere, plants can’t absorb nitrogen directly from the atmosphere, the nitrogen can be absorbed by nitrogen fixing bacteria though, this bacteria is present in soil. Some plants also contain nitrogen fixing bacteria in their roots
  • Nitrogen fixing bacteria convert nitrogen in the air into nitrates in the soil, these nitrates can then be absorbed by plants
43
Q

Describe the process of the nitrogen cycle

A
  • Nitrogen from the air is converted to nitrates by nitrogen fixing bacteria
  • The nitrates are then absorbed by plants and used to make amino acids
  • The amino acids pass into animals when they eat the plants
  • Animals release waste products and both plants and animals eventually die so there is nitrogen in waste products and dead remains
  • Decomposers then convert nitrogen into ammonia
  • Then nitrifying bacteria convert the ammonia into nitrates, these can be absorbed again by the plants and the cycle continues
  • Remember some bacteria in the soil called denitrifying bacteria breaks down nitrates into nitrogen gas which returns into the atmosphere
44
Q

Why do farmers use fertilisers?

A

They contain nitrates which help plants grow better

45
Q

What is crop rotation?

A

Growing different crops each year on a rotation basis, this is done because certain crops have nitrogen fixing bacteria in their roots, this means the soil gains more nitrates. Also, different crops remove different nutrients from the soil so if you keep the same crops all the time they will absorb all of a certain type of nutrient from the soil

46
Q

What are indicator species?

A

Species that can live in polluted condition, this indicates whether pollution is present because the species that can’t live in polluted conditions will not be present when pollution is present

47
Q

Give some examples of indicators of air pollution

A
  • Lichen, some species of lichen can only grow where there is no pollution, other species of lichen can grow where there is pollution. This means that we can tell if the air has been polluted from the species of lichen growing on trees
  • Blackspot, it’s a fungus that infects roses. It is damaged by sulfur dioxide so where there’s air pollution the roses are clear of the fungus
48
Q

Give some examples of indicators of water pollution

A
  • Bloodworms and sludgeworms, they can live in water with little oxygen so they’re found in polluted water
  • Stonefly larvae, mayflies and caddisflies can only live in water that contains lots of oxygen, this means they’re indicators of unpolluted water
49
Q

What is decay?

A

The breakdown of materials by microorganisms

50
Q

What factors affect the decay rate?

A
  • Temperature
  • Water content
  • Oxygen availability
51
Q

How can decay of food be prevented?

A
  • Refrigeration because it is too cold for most microorganisms to grow quickly
  • Salting food because it causes water to move out of bacterial cells by osmosis
  • Packing food in nitrogen because it means there is no oxygen for microorganism to respire
52
Q

What can garden and kitchen waste be used to make?

A

Compost, the conditions in the compost can be controlled to encourage the growth of decay microorganisms, these conditions should be moist, warm and aerobic (oxygen present)

Biology GCSE (11 decks)

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