Flashcards in B3.4 Humans And Their Environment Deck (54)
What are the three main headings for effects of increasing human population on the environment?
- More waste
- More pressure on materials
- Less land for animals
What areas does waste pollute?
How is the water polluted?
- Sewage and toxic chemicals from industries pollute lakes, rivers and oceans
How does waste pollute the land?
- Landfill sites
- Nuclear waste being dumped
Why has the human population increased? (3 points)
- Better healthcare/medicine
- Better sanitation
- Better more modern farming methods
How is the air polluted?
- Sulphur dioxide : causes acid rain
- Carbon dioxide : global warming
How is pressure put on materials by increasing population?
- Higher standard of living, more materials taken to make commodities
- More manufacturing : more energy used
What four human activities create less land for animals?
- Quarrying for metal ores
- Dumping waste
- 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
What is bioaccumulation?
Pesticides building up in the food chain, causing top consumers to die.
Where is carbon locked up?
- Oceans, lakes and ponds
- Green plants - stored as carbon compounds and removed from atmosphere in photosynthesis
- Peat bogs
What are conditions in the areas of lands peat bogs occur in like?
- Lack of oxygen
What makes the conditions of peat lands ideal?
They prevent total decomposition.
What is peat?
Partially rotted remains of dead plant that have accumulated on top of each other for thousands of years.
What three things are peat bogs destroyed for?
- Drained for farmland
- Cut up and burnt as fuel
- Sold as compost
How can people reduce peat big destruction?
By buying peat free compost so there is less demand for it.
What is the problem with destroying peat bogs?
The peat comes into contact with more oxygen and begins to decompose again releasing carbon dioxide.
Describe global warming.
- 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.
Name 4 greenhouse gases.
- Carbon dioxide
- Water Vapour
- Nitric oxide
What are the effects of global warming?
- 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
What are the three main headings for the effects of deforestation?
- More methane in atmosphere
- More carbon dioxide in atmosphere
- Less biodiversity
Why does deforestation take place? (6)
- 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
How is methane in the atmosphere increased by deforestation? (2)
- More rice fields = more decomposers feeding on them = more methane
- More cattle produce more methane gas
How does deforestation increase carbon dioxide levels?
- Carbon dioxide produced when trees burnt
- Decomposers feed on dead wood = release carbon dioxide
- Less trees = less carbon dioxide taken in drying photosynthesis
How does deforestation cause less biodiversity?
- Habitats contain different species, when these habitats are destroyed many species become endangered.
What effects does a decrease in biodiversity have?
- Human use is reduced e.g new foods, medicine and clothes reduced.
- Disruptions in food chains
The variety of different species in a habitat.
What is biofuel?
Fuel produced from biological material which is renewable and sustainable
How is biofuel made?
- Fermentation using yeast/bacteria
- The ethanol is then distilled to remove excess yeast and glucose
Describe the chemical process that occurs when sugar cane juices are used to make biofuel.
Sucrose ---anaerobic respiration---> ethanol + carbon dioxide
Describe the chemical process that occurs when maize is used to make biofuel.
- Starch --carbohydrases ---> simple sugars (e.g glucose)
- Simple sugars ---anaerobic respiration ---> ethanol + carbon dioxide
What are the disadvantages of biofuel?
- 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.
What is used to make biogas?
- Human sewage
- Animal waste
- Unwanted plant material
What is the process of making biogas?
- Bacteria (e.g methobacteria) breaks down carbohydrates in waste during aerobic respiration
- Methane (70%) and carbon dioxide (30%) is produced
Why do conditions need to be anaerobic when producing biogas?
Otherwise only carbon dioxide will be produced which doesn't burn so cannot be used as fuel
What type of reaction happens in biogas generators?
An exothermic reaction.
Why are biogas generators insulated in cold countries?
- 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
What temperature does the biogas reaction work at?
30 degrees Celsius
Why are biogas generators insulated in hot countries?
- 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
What are the by products of biogas generation used for?
What are the two types of biogas generator?
- Batch generator
- Continuous generator
How does a batch generator work?
- Makes biogas in small batches
- Manually loaded up with waste, left to digest, by products cleared away at the end of each season
How do continuous generators work?
- Makes biogas generators all the time
- Waste is continuously fed in so biogas is produced at a steady rate
- Used for large scale products
What is the advantage to batch generators?
They are cheaper as waste doesn't have to mechanically pumped in and removed all the time.
What is the advantage to continuous generators?
More convenient, doesn't have to be continually loaded and cleaned.
What are the advantages to biogas?
- 'Carbon neutral'
- insignificant amounts of sulphur dioxides
- Material is cheap and renewable
- Waste disposal system (waste could otherwise cause disease and pollution)
How is food production efficiency improved?
- Reducing stages in the food chain
- Restricting movement of animals
- Controlling the temperature of animals surroundings
How is food production efficiency improved by reducing the stages in the food chain?
At each stage in a food chain, less material and energy is contained in the organism's biomass.
What is mycoprotein used for?
Used to make meat substitutes for vegetarians.
What is mycoprotein made from?
A fungus (fusarium's) protein
What are two uses of mycroproteins?
- Increases protein for human consumption
- Useful for when land is infertile = sustainable food source
How is mycroprotein grown?
- 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)
What are the two ways of fishing sustainably?
- 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