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Biology Chapter 6 > Planetary Boundaries > Flashcards

Planetary Boundaries Flashcards

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1
Q

Define planetary boundaries.

A

Limits between which global systems must operate to prevent abrupt and irreversible environmental change.

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2
Q

Which 4 planetary boundaries are at high risk?

A
  1. Biogeochemical flows
  2. Biodiversity integrity
  3. Climate change
  4. Land system change
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3
Q

Which 3 planetary boundaries are safe?

A
  1. Ozone depletion
  2. Freshwater use
  3. Ocean acidification
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4
Q

Which 2 planetary boundaries aren’t quantified?

A
  1. Atmospheric aerosols

2. Novel entities

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5
Q

How are biofuels made?

A

A biological process such as anaerobic digestion of plant material of agricultural, domestic and industrial waste.

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6
Q

What is the difference between first generation biofuels and second generation biofuels?

A

First generation biofuels = made from sugars and vegetable oils found in arable crops which are easily extracted
Second generation biofuels = made from cellulose and lignin from woody crops, harder to extract

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7
Q

Give 5 social, economic and technical issues of biofuel.

A
  1. Land use to grow food has been used for biofuel production - less food to eat / export.
  2. Sustainable biofuel production requires sustainable planting and efficient technical systems.
  3. Deforestation
  4. Reduction in water availability
  5. Combustion of biodiesel releases more NO2 than fossil fuels
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8
Q

How is bioethanol made? 4 stages.

A
  1. Plant material crushed. Stored starches digested with carbohydrates to release sugars.
  2. Sucrose is crystallised out, leaving molasses (high in glucose + fructose)
  3. Glucose + fructose fermented by yeast
  4. Mixture heated by burning fibrous waste (bagasse) from the initial plant material. Pure ethanol is then distilled.
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9
Q

What can biodiesel be made from?

A

Vegetable oils; soya, rapeseed and palm oil

Algae

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10
Q

What is the equation for the production of biodiesel?

A

Methanol + linoleic acid (fatty acid) — methyl linoleate + water

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11
Q

Why is biodiesel more sustainable than normal petrol/diesel?

A

It contains less carbon and more hydrogen and oxygen, so about 60% of carbon emissions are released if it’s pure. It produces less carbon and carbon monoxide, but more nitrous oxide.

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12
Q

What is biogas?

A

A mixture of gases - 60% methane, 40% carbon dioxide. It is made by the bacterial digestion of biodegradable waste materials e.g. Human/animal waste.

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13
Q

How is biogas made? 3 stages.

A
  1. Macromolecules are aerobically digested by amylases, proteases and lipases to sugars, Amino acids, fatty acids and glycerol.
  2. Acetogenesis
  3. Methanogenesis
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14
Q

What is athenogenesis?

A

Second stage of making biofuel. An aerobic process where short fatty acid chains are made, especially ethanoic acid, and CO and H2 are produced.

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15
Q

What is methanogenesis?

A

The final, anaerobic stage of biogas production.

C6H12O6 — 3CH4 + 3CO2

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16
Q

Why is the biosphere integrity boundary important?

A

The interaction of species produces ‘ecosystem services’ like absorbing CO2 which the biosphere depends on.

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17
Q

What biospheres have been affected by human activity?

A

Marine, tundra, coral reefs and coastal plains

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18
Q

How have marine biospheres biodiversity been reduced? (4)

A

If activity continues like it is now, by 2100 half of all marine species will be extinct.
Oceans are polluted with acid, oil, plastics and sewage effluent.
The pesticide DDT has been found in Antarctic waters so it’s global.
Evidence correlates marine pollution with decline in phytoplankton, which will have an effect on higher trophic levels.

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19
Q

How have tundra ecosystems been affected by human activity?

A

It has been altered as the temperature has risen - species are growing now where before only lichens and Mosses grew.

20
Q

How has the coral reef been impacted by human activity?

A

Coral reef bleaching causes species loss. The warm temperature causes zooxanthellae to leave (gives coral its colour). Their photosynthesis feeds corals so eventually they die.

21
Q

How have coastal communities been affected by human activity?

A

Mangroves, salt marshes and sea grass meadows absorb CO2 extremely well, but they are being submerged and dying due to loss of water by osmosis from the salt water

22
Q

Why has the land-system change boundary been crossed?

A

It represents the misuse of land that results in too little food being produced.

23
Q

Why has the land-system change occurred? (3)

A
  1. Expansion of farming and raising livestock
  2. Making biofuels
  3. Urban development
24
Q

What are 3 ways we could reverse the land-system change boundary being crossed?

A
  1. Farming concentrated in most productive areas
  2. Global meat consumption reduced
  3. Genetically modified plants
25
Q

Explain why the biogeochemical flows boundary has been crossed.

A

The biogeochemical flow refers to the recycling of minerals through the ecosystem. Agricultural fertilisers have been used too much so phosphorus and nitrogen can no longer self renew. This has also caused eutrophication.

26
Q

Why are mineral cycles important?

A

They are essential for maintaining the availability of elements in the ions that are absorbed in the food web.

27
Q

How have CFC’s caused the breakdown of Ozone?

A

Ozone is usually in equilibrium (3O2-2O3) however CFCS are halogenated hydrocarbons which shift the equilibrium to favour the breakdown of ozone. Also, CFCs release chlorine radicals which breakdown ozone rapidly.

28
Q

What were CFCs used for?

A

Propellants in spray cans
Solvents
Refrigerator coolants
Packaging

29
Q

Why is ozone depletion damaging to humans?

A

More UV light allowed in means higher risk of skin cancer and cataracts.

30
Q

What has been the change to the oceans pH and why?

A

It has reduced from 8.16 to 8.03.

This is because of more CO2 dissolving in water.

31
Q

What are the equations that explain why more CO2 in the air means a lower pH of water?

A

H20 + CO2 - H2CO3
H2CO3 - H+ + HCO3
HCO3 - H+ + CO32-

32
Q

2 ways that lower pH has damaged marine creatures.

A

Low pH makes CACO3 leave molluscs, coral shells and arthropod exoskeletons which makes them vulnerable to damage. (CACO3 + H+ - CA2+ + HCO3-)
Fishes gills get damaged by low pH
Fish farms may have to change species or relocate.

33
Q

Where can freshwater be found? (11 possible answers)

A 
Ice sheets
Ice caps 
Glaciers
Icebergs 
Bogs
Ponds 
Lakes
Rivers
Streams 
Groundwater in aquifers
Groundwater in lakes
34
Q

Give 7 reasons why freshwater availability has decreased.

A
  1. Changing landscapes - deforestation
  2. Agriculture
  3. Increased demand from warmer climates
  4. Climate change
  5. Increased population
  6. Increased use
  7. Water pollution.
35
Q

Explain how climate change has lead to the decrease in water availability.

A

Ice caps melting increases water at first but then causes flooding and drought which decreases it.
Rising sea levels contaminate fresh water with sea water.

36
Q

Give 6 ways that provision of freshwater is underway.

A
  1. Water conservation
  2. Water efficiency
  3. Wastewater reclamation - irrigation and industrial use
  4. Urban runoff + storm water recapture
  5. Drip irrigation system
  6. Desalination
37
Q

Explain how drip irrigation systems are better than normal systems.

A

They give the water directly to the roots rather than spraying it so less is used.

38
Q

Explain how desalination works.

A

Solar stills distil sea water using heat from the sun.
Sea water and fresh water are separated by a selectively permeable membrane and pressure is put on the sea water so that reverse osmosis can occur, against the water gradient. It requires energy.

39
Q

Give 2 environmental problems with desalination.

A
  1. Brine is discharged and it is denser than seawater so damaged the seabed
  2. It requires the burning of fossil fuels to heat the system
40
Q

What are atmospheric aerosols?

A

Microscopic particles put into the atmosphere by combustion of fuels and from dust from digging and quarrying.

41
Q

Give the 3 main problems with atmospheric aerosols loading.

A
  1. They exacerbate lung problems - PM10 and PM2.5
  2. Deposition on leaves means less sunlight so less photosynthesis so lower crop yields
  3. Sulphates reflect light but soot absorbs and re-radiates it. The balance of these two effects aren’t clear.
42
Q

What are PM10 and PM2.5 and what do they do?

A

They are atmospheric aerosols. PM10 can get stuck in the lungs and cause cancer. PM2.5 travels in capillaries and increase the risk of death by cardiovascular disease.

43
Q

What does the novel entities boundary encompass?

A

Organic pollutants, radioactive materials, nano-materials and micro plastics.

44
Q

Why is the novel entities boundary in place?

A

There are estimated 100,000 chemicals in the world and they may interact with each other and cause additional harmful effects.

45
Q

Why was the novel entities boundary name updated?

A

To reflect the increasing use of new technologies and materials.

Biology Chapter 6 (7 decks)

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