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Biology Unit 3 > B3.4 Humans And Their Environment > Flashcards

B3.4 Humans And Their Environment Flashcards

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1
Q

What are the three main headings for effects of increasing human population on the environment?

A
  • More waste
  • More pressure on materials
  • Less land for animals
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2
Q

What areas does waste pollute?

A
  • Land
  • Water
  • Air
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3
Q

How is the water polluted?

A
  • Sewage and toxic chemicals from industries pollute lakes, rivers and oceans
  • Eutrophication
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4
Q

How does waste pollute the land?

A
  • Bioaccumulation
  • Landfill sites
  • Nuclear waste being dumped
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5
Q

Why has the human population increased? (3 points)

A
  • Better healthcare/medicine
  • Better sanitation
  • Better more modern farming methods
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6
Q

How is the air polluted?

A
  • Sulphur dioxide : causes acid rain

- Carbon dioxide : global warming

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7
Q

How is pressure put on materials by increasing population?

A
  • Higher standard of living, more materials taken to make commodities
  • More manufacturing : more energy used
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8
Q

What four human activities create less land for animals?

A
  • Quarrying for metal ores
  • Farming
  • Building
  • Dumping waste
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9
Q

Explain eutrophication.

A
  • Fertilisers and pesticides applied to the soil is washed into waterways
  • High levels of nitrates and phosphates cause excess algae growth
  • Algae blocks out sunlight, killing aquatic plants
  • Less plants = less photosynthesis = less O2 in water
  • More dead plants = more decomposers respiring = O2 used up
  • Decrease in O2 levels = fish and invertebrates die
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10
Q

What is bioaccumulation?

A

Pesticides building up in the food chain, causing top consumers to die.

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11
Q

Where is carbon locked up?

A
  • Oceans, lakes and ponds
  • Green plants - stored as carbon compounds and removed from atmosphere in photosynthesis
  • Peat bogs
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12
Q

What are conditions in the areas of lands peat bogs occur in like?

A
  • Acidic
  • Waterlogged
  • Lack of oxygen
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13
Q

What makes the conditions of peat lands ideal?

A

They prevent total decomposition.

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14
Q

What is peat?

A

Partially rotted remains of dead plant that have accumulated on top of each other for thousands of years.

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15
Q

What three things are peat bogs destroyed for?

A
  • Drained for farmland
  • Cut up and burnt as fuel
  • Sold as compost
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16
Q

How can people reduce peat big destruction?

A

By buying peat free compost so there is less demand for it.

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17
Q

What is the problem with destroying peat bogs?

A

The peat comes into contact with more oxygen and begins to decompose again releasing carbon dioxide.

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18
Q

Describe global warming.

A
  • Radiation from the sun in the form of light waves enters the atmosphere and warms the earth.
  • Earth produces I.R - some is absorbed by an insulating layer of greenhouses gases (e.g CO2 and methane) and reflected back to earth making it warmer.
  • Increased levels of these gases trap more emitted heat causes a greater increase in earth’s temperature.
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19
Q

Name 4 greenhouse gases.

A
  • Carbon dioxide
  • Methane
  • Water Vapour
  • Nitric oxide
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20
Q

What are the effects of global warming?

A
  • Unpredictable weather conditions (flooding, draughts, freak winds)
  • Rise in sea levels (species and countries disappear)
  • Decrease in biodiversity (less human use and disruption in food chains)
  • Change in distribution of organisms (some species move to adapt to weather conditions e.g to higher altitudes)
  • Change in migration patterns
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21
Q

What are the three main headings for the effects of deforestation?

A
  • More methane in atmosphere
  • More carbon dioxide in atmosphere
  • Less biodiversity
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22
Q

Why does deforestation take place? (6)

A
  • To build roads and new houses
  • Timber as building materials (logging)
  • To farm land for more food (e.g rice fields and cattle)
  • To burn as fuel
  • Space for crop for biofuel
  • Paper from wood
23
Q

How is methane in the atmosphere increased by deforestation? (2)

A
  • More rice fields = more decomposers feeding on them = more methane
  • More cattle produce more methane gas
24
Q

How does deforestation increase carbon dioxide levels?

A
  • Carbon dioxide produced when trees burnt
  • Decomposers feed on dead wood = release carbon dioxide
  • Less trees = less carbon dioxide taken in drying photosynthesis
25
Q

How does deforestation cause less biodiversity?

A
  • Habitats contain different species, when these habitats are destroyed many species become endangered.
26
Q

What effects does a decrease in biodiversity have?

A
  • Human use is reduced e.g new foods, medicine and clothes reduced.
  • Disruptions in food chains
27
Q

Define biodiversity.

A

The variety of different species in a habitat.

28
Q

What is biofuel?

A

Fuel produced from biological material which is renewable and sustainable

29
Q

How is biofuel made?

A
  • Fermentation using yeast/bacteria

- The ethanol is then distilled to remove excess yeast and glucose

30
Q

Describe the chemical process that occurs when sugar cane juices are used to make biofuel.

A

Sucrose —anaerobic respiration—> ethanol + carbon dioxide

31
Q

Describe the chemical process that occurs when maize is used to make biofuel.

A
  • Starch –carbohydrases —> simple sugars (e.g glucose)

- Simple sugars —anaerobic respiration —> ethanol + carbon dioxide

32
Q

What are the disadvantages of biofuel?

A
  • Demand of biofuel = greater demand on forest land
  • Less land used for food crop = food prices go up
  • Crops grow slowly in low light and temperature lands, not enough for the demand
  • Carbon dioxide emissions in transporting, harvesting and growing crop.
33
Q

What is used to make biogas?

A
  • Human sewage
  • Animal waste
  • Unwanted plant material
34
Q

What is the process of making biogas?

A
  • Bacteria (e.g methobacteria) breaks down carbohydrates in waste during aerobic respiration
  • Methane (70%) and carbon dioxide (30%) is produced
35
Q

Why do conditions need to be anaerobic when producing biogas?

A

Otherwise only carbon dioxide will be produced which doesn’t burn so cannot be used as fuel

36
Q

What type of reaction happens in biogas generators?

A

An exothermic reaction.

37
Q

Why are biogas generators insulated in cold countries?

A
  • Temperatures in cold countries are usually below the optimum temperature for the reaction
  • Heat from reaction (exothermic releases energy) retained in generator to increase rate of reaction
38
Q

What temperature does the biogas reaction work at?

A

30 degrees Celsius

39
Q

Why are biogas generators insulated in hot countries?

A
  • The optimum temperature for the process is less than the external temperature
  • Insulation cools the generator and keeps it at the optimum - stops denaturing of the enzymes
40
Q

What are the by products of biogas generation used for?

A

Fertilisers

41
Q

What are the two types of biogas generator?

A
  • Batch generator

- Continuous generator

42
Q

How does a batch generator work?

A
  • Makes biogas in small batches

- Manually loaded up with waste, left to digest, by products cleared away at the end of each season

43
Q

How do continuous generators work?

A
  • Makes biogas generators all the time
  • Waste is continuously fed in so biogas is produced at a steady rate
  • Used for large scale products
44
Q

What is the advantage to batch generators?

A

They are cheaper as waste doesn’t have to mechanically pumped in and removed all the time.

45
Q

What is the advantage to continuous generators?

A

More convenient, doesn’t have to be continually loaded and cleaned.

46
Q

What are the advantages to biogas?

A
  • ‘Carbon neutral’
  • insignificant amounts of sulphur dioxides
  • Material is cheap and renewable
  • Waste disposal system (waste could otherwise cause disease and pollution)
47
Q

How is food production efficiency improved?

A
  • Reducing stages in the food chain
  • Restricting movement of animals
  • Controlling the temperature of animals surroundings
48
Q

How is food production efficiency improved by reducing the stages in the food chain?

A

At each stage in a food chain, less material and energy is contained in the organism’s biomass.

49
Q

What is mycoprotein used for?

A

Used to make meat substitutes for vegetarians.

50
Q

What is mycoprotein made from?

A

A fungus (fusarium’s) protein

51
Q

What are two uses of mycroproteins?

A
  • Increases protein for human consumption

- Useful for when land is infertile = sustainable food source

52
Q

How is mycroprotein grown?

A
  • Grown in fermenters on a food supply (glucose syrup)
  • Bubbles of oxygen for respiration as fungus needs to be in aerobic conditions
  • Conditions need to be sterile so no bacteria competes with fungus (sterilise air, fermenter and block leaks)
53
Q

What are the two ways of fishing sustainably?

A
  • Fishing quotas : limits amount and size of fish caught in certain areas, prevents certain species being overfished
  • Net size : bigger hole sizes so younger fish can escape and breed
    smaller overall net size
54
Q

What are the disadvantages to efficient food production?

A
  • Cruel conditions for animals
  • Crowded conditions spread diseases
  • Antibiotics given to animals enter humans when eaten - increases bacterial immunity
  • Temperature controlling needs energy

Biology Unit 3 (4 decks)

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