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Flashcards in Topic 4 Deck (17)
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1
Q

Understand the terms population, community, habitat and ecosystem

A

Population - All the organisms of one species in a habitat

Community - All the different species in a habitat

Habitat - The area/place in which an organism lives

Ecosystem - All of the organisms living in a particular area and all the abiotic (non-living) conditions.

2
Q

Explain how quadrats can be used to estimate the population size of an organism in two different areas

A

Quadrat are usually 1m2 and split into smaller squares. Just count the organisms within the quadrat. Repeat 5 times and find the mean. Now multiply the number of that organism found within the size (in m2) of the are you are investigating (all squares).

Repeat with another area and compare

3
Q

Explain how quadrats can be used to sample the distribution of organisms in their habitats

A
  • Quadrats place in different areas at random
  • One is chosen
  • Population counted (must be either plants or very slow moving animals)
  • Repeated in different areas
  • Population counted
  • Now you can compare results and see where population is more dense (there might be more flowers near a river bed)
4
Q

Explain the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers

A

Different trophic levels, mean different feeding levels

Producers: Produces its own food from the sun (plants photosynthesising)
Primary Consumers: Animals that eat plants
Secondary Consumers: Animals that eat primary consumers
Tertiary Consumers: Animals that eat secondary consumers
Decomposers: Bacteria and fungi that break down dead materials and waste (by excreting extracellular enzymes onto dead/decaying matter to digest it). they respire carbohydrates to give out carbon dioxide.

5
Q

Understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

A

Food Chain:
A food chain shows the flow of energy up the food chain. It can only show one organism at each trophic level, also you cannot tell whether the organism is feeding at more than one.

Food Web:
A food web gives a better understanding of a certain ecosystem by linking several animals within a habitat showing which organisms consumes which etc. A food web basically just shows multiple different food chains, that are all linked together. They show multiple different trophic levels including multiple prey and multiple predators. This means an organism has the potential to be a secondary or tertiary consumer at the same time.

Pyramid of Number:
A pyramid of numbers shows the number of each organism (of each trophic level of a certain food chain) by the area of the block in the pyramid.

Pyramid of Biomass:
A pyramid of biomass is a bit like a pyramid of numbers, only it represents the dry mass of each consumer (and producer), again, by the area of a pyramid block.

Pyramid of Energy:
A pyramid of energy, again looks like a pyramid of number/biomass, but it shows the transfer/flow of energy through the food chain.

6
Q

Understand the transfer of substances and of energy along a food chain

A

Plants use energy from the sun in photosynthesis, this energy makes its way through the food chain as animals eat the plants and each other.

However, not all the energy that’s available to the organisms in a trophic level is passed on to the next trophic level, this is because 90% of the energy is lost in various ways. These include…

  • Indigestible energy is not take in in the first place (fibre), it is just digested out
  • Lots of energy is used for the 7 life processes
  • Lots of the energy is lost in heat

NOTE: Only around 10% of energy becomes biomass (eg. it is stored for growth etc). This is transferred onto the next trophic level once the organism is eaten.

7
Q

Explain why only about 10% of energy is transferred from one trophic level to the next.

A

Much energy is lost so not all energy an organism takes in is conserved until it dies and then transferred onto the next trophic level when it is eaten. The main causes of energy loss are…

  • Heat energy
  • Energy needed for the 7 life process
  • energy in indigestible foods (fibre) are not ‘absorbed’

This results in around 90% of the energy being used, so only 10% is passed onto the next trophic level.

8
Q

Describe the stages in the water cycle, including evaporation, transpiration, condensation and precipitation

A

Evaporation - This is where water (from the ground) gets warmed (usually from sunlight). When this happens, the water molecules gain energy and they start to move lots more, eventually they turn into a gas.

Transpiration - Transpiration is evaporation form plants/leaves

Condensation - When the warm water vapour is carried upwards (convection currents). However, the higher you go the colder it gets. The water vapour eventually cools down and condenses, forming clouds.

Precipitation - A fancy name for rain/snow/hail

9
Q

Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion

A

Respiration - Breathing basically. This releases carbon dioxide back into the air

Photosynthesis - Carbon is taken in (by the plants)

Decoposition - When plants and animals die, decomposers decompose them. This introduces carbon back into the soil

Combustion - Things like wood and fossil fuels are burned. This releases carbon dioxide back into the air

The carbon dioxide in the air is then taken in by the plants and the cycle continues (this is why plants are so important)

10
Q

Describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required)

A

Nitrogen fixing bacteria - This turns atmospheric nitrogen into nitrogen compounds (in the soil) that plants can use.

Decomposers - Turns proteins and urea (from plants and animals) into ammonia

Nitrifying Bacteria - This turns ammonia into nitrates

Denitrifying Bacteria - This turns nitrates back into atmospheric nitrogen gas

The process repeats

NOTE: Some of these bacterium live in the soil and some live on the root nodules of plants.

11
Q

Understand the biological consequences of pollution of air by sulfur dioxide and by carbon monoxide

A

Sulfur Dioxide:
When fossil fuels are burnt, sulfur dioxide is released (from sulfur impurities in the fuel). When it mixes with rain clouds, it forms acid rain (dilute sulfuric acid). This kills fish and trees as it causes lakes to become more acidic and can damage leaves and release toxic substance from the soil, meaning it is hard for the tree to take up nutrients from the soil.

Carbon Monoxide:
When fossil fuels are not burnt with enough air (incomplete combustion), carbon monoxide is produced. This is a poisonous gas and binds to haemoglobin in red blood cells, preventing the red blood cells from carrying enough oxygen to muscles.

12
Q

Understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases

A

Greenhouse gases are bad as they trap heat from the sun in the earth atmosphere. Examples include:

  • Water vapour
  • Carbon dioxide (deforestation, industrial processes, car exhausts)
  • Nitrous oxide (fertilisers, vehicle engines, natural release from bacteria)
  • Methane (rotting plants rice growing, cattle rearing)
  • CFCs (NOTE: CFCs are man-made chemicals, they are basically not produced anymore but some still are and are leaking from old products that contain them)
13
Q

Understand how human activities contribute to greenhouse gases

A

Carbon Dioxide:
Source: Car exhausts, industrial processes, burning of fossil fuels
Things affecting the level of CO2: deforestation

Methane:
Natural Source: Rotting plants in marshland
Manmade Source: Rice growing and cattle rearing

Nitrous Oxide:
Natural Source: Bacteria in the soil and the ocean
Manmade Source: Released in soils form the use of fertilisers, vehicle engines and industry

CFCs:

  • Very powerful greenhouse gas
  • Manmade chemicals used in aerosol sprays and fridges
  • It damages the ozone layer, creating holes causing more UV light to reach humans
14
Q

Understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences

A
  • The temperature of earth is balanced between heat from the sun and heat radiated back out to space
  • Gases in the atmosphere absorb most of the heat, which keeps us warm
  • If the earth heats up, it causes global warming, which is a type of climate change and causes other climate changes (rainfall patters)
  • Climate changes could lead to changes of crop grown patters, or flooding because of the polar ice caps melting
  • The increased temperature and sea level, causes more evaporation, meaning more rain
  • This leads to natural disasters, like hurricanes or typhoons
15
Q

Understand the biological consequences of pollution of water by sewage, including increases in the number of micro-organisms causing depletion of oxygen

A

Water Pollution by Sewage - Consequences:

Reproduction of Micro-Organisms:

  • Sewage is rich in minerals and nutrients that provides large amount of energy to allow organisms such as decomposers to reproduce, increasing their population
  • Sewage in rich in nutrients (phosphates) that will encourage the growth of algae, causing algae bloom to form on the surface

Depletion of Oxygen:

  • Decomposers will respire aerobically to break down sewage and dead plants (from lack of sunlight due to algae bloom) so will cause depletion of oxygen, causing aquatic organisms to die
  • Sewage may contain bacteria that will respire aerobically, using up oxygen in the water
  • Sewage will increase population of organisms in the water so will cause more aerobic respiration to take place, further increasing the depletion of oxygen
16
Q

Understand that eutrophication can result from leached minerals from fertiliser

A

Nitrates and phosphates can leak from mineral fertilisers that are put on fields. If it rains, they are easily leached into rivers and lakes. This results in eutrophication.

  • The extra nutrients causes algae to grow super fast. This blocks out the light
  • Plants in the river (before the algae) cannot photosynthesise due to low light. They die.
  • With more food (dead plants) available, microorganisms living in the water rapidly increase in number and deplete/use up all the oxygen in the water.
  • Organisms, like fish for example, that need oxygen, die.
17
Q

Understand the effects of deforestation, including leaching, soil erosion, disturbance of the water cycle and of the balance in atmospheric oxygen and
carbon dioxide

A

Leaching:
Trees leach nutrients when they are alive, but return nutrients to the soil when they die. When trees are cut down, nutrients get leached but not returned, resulting in infertile soil.

Soil Erosion:
When trees are removed, soil can be washed away by rain etc as tree roots hold solid together (but there will be no tree roots, as there will be no trees)

Disturbance of the Water Cycle:
Trees take up water, when they are cut down, water runs straight into rivers, causing floods. Also, the local climate gets drier as there is much less transpiration occurring.

Disturbance of the Balance of Carbon Dioxide and Oxygen:
When trees die, carbon dioxide is naturally released. When they are burnt, all the carbon dioxide is released at once. Alternatively, if wood is used in furniture etc. the carbon is stored and not released, disrupting the carbon cycle.

Fewer trees means fewer photosynthesis means less O2.