Biology 3b Flashcards
What is the population of the world?
Over 6billion and its increasing very quickly
Why is the population increasing?
Mostly due to modern medicine and farming methods, which have reduced the number of people dying from disease and hunger
How does an increasing population effect the environment?
Adds pressure to the environment as we take the resources we need to survive, people are also demanding a higher standard of living and luxuries like cars and computers, so more raw materials like oil for plastics are used and energy for manufacturing processes, meaning we’re taking more and more resources more and more quickly
What affect does this have on the environment?
Many raw materials are being used up quicker than they’re being replaced so if we carry on this way, they’ll start to run out
What also happens as we produce more things?
We produce more waste and unless its properly handles, more harmful pollution is caused
How can waste affect water?
Sewage and toxic chemicals from industry can pollute lakes, rivers and oceans, affecting the plants and animals that rely on them for survival, including humans. And the chemicals used on land e.g. fertilisers, can be washed into water
How can waste affect the land?
We use toxic chemicals for farming e.g. pesticides and herbicides. We also bury nuclear waste underground, and we dump a lot of household waste in landfill sites
How can waste affect the air?
Smoke and gases released into the atmosphere can pollute the air e.g. sulfur dioxide can cause acid rain
What are the four main ways that humans reduce the amount of land and resources available to other animals and plants?
Building, farming, dumping waste and quarrying for metal ores
How is carbon present in the atmosphere?
As carbon dioxide
What can too much CO2 in the atmosphere cause?
Global warming
Where can CO2 be sequestered (locked up) in natural stores?
Oceans, lakes and ponds, green plants where its stored as carbon compounds, green plants remove CO2 from the atmosphere during photosynthesis and peat bogs
What does the temperature of the Earth depend on?
Its a balance between the heat it gets from the sun and the heat it radiates back out to into space
What is the greenhouse effect?
Gases in the atmosphere naturally act like an insulating layer. They absorb most of the heat that would normally be radiated out into space, and re-radiate it in all directions including back towards Earth
What would happen if this didn’t happen?
Then at night there’d be nothing to keep any hear in and it would get very cold
What are the different gases in the atmosphere that help keep heat in called?
Greenhouse gases and the main ones are carbon dioxide and methane but the levels of these gases are rising quite sharply
Why is the Earth gradually heating up?
Because of the increasing levels of greenhouse gases this is global warming which is a type of climate change and causes other types of climate change e.g. changing rainfall patterns
What is deforestation?
The cutting down of forests, causing big problems when done on a large scale like cutting down rainforests
Why does deforestation happen?
To provide timber to use as building material, to clear more land for farming which is important for food e.g. from more rice fields or crops for biofuels based on ethanol, and also to produce paper from wood
What are the four main problems of deforestation?
More methane in the atmosphere, more carbon dioxide in the atmosphere, less carbon dioxide taken in and less biodiversity
How is more methane produced?
Rice is grown in warm, waterlogged conditions ideal for decomposers, these organisms produce methane so more is released into the atmosphere. Also cattle produce methane and rearing cattle means that more methane is released
How is more carbon dioxide produced?
Carbon dioxide is released when trees are burnt to clear land as carbon in wood doesn’t contribute to atmospheric pollution until it is burnt. Microorganisms feeding on bits of dead wood release carbon dioxide as a date product of respiration
Why is less carbon dioxide taken in?
Cutting down loads of trees means that the amount of carbon dioxide removed from the atmosphere during photosynthesis is reduced
What is biodiversity?
The variety of different species in a habitat, the more species, the greater the biodiversity
Why is there less biodiversity?
Habitats like tropical rainforests can contain a huge number of different species so when they are destroyed there is a danger of many species becoming extinct.
What does less biodiversity cause?
A number of lost opportunities e.g. there are probably loads of useful products that we will never know about because the organisms that produced them have become extinct. Newly discovered plants and animals are a great source of new foods, new fibres for clothing and new medicines
What are bogs?
Areas of land that are acidic and waterlogged. Plants that live in bogs don’t fully decay when they die, because theres not enough oxygen. The partly rotted plants gradually build up to form peat. The carbon in the plants is stored in the peat instead of being released
How is peat used as fuel?
Peat bogs are often drained so that the area can be used as farmland, or the peat is cut up and dried to use as fuel. Peat is also sold to gardeners as compost
When does peat start to decompose?
When the bogs are drained so carbon dioxide is released. If we continue to destroy peat bogs, more carbon dioxide will be released adding to the greenhouse effect.
What is one way people can help to reduce the greenhouse effect?
By buying peat-free compost for their gardens e.g. manure, leaf mould or bark chippings, to reduce the demand for peat
How is the sea affected by global warming?
As the sea gets warmer it expands causing the sea level to rise. Sea level has risen a little bit over the last 100 years. If it keeps rising it’ll be bad news for people living in low-lying places like the Netherlands, East Anglia and the Maldives-they’d be flooded. Also water thats trapped on land as ice is melted and runs into the sea, expanding it even more
How is the weather affected by global warming?
Some regions will suffer more extreme weather e.g. longer and hotter droughts. Hurricanes form over water thats warmer than 27degrees C. So with more warm water-more hurricanes. However climate is complicated and its hard to predict exactly what’ll happen but the people working on it say it doesn’t look good
How is the distribution of wild animal and plant species affected by global warming?
Some species may become more widely distributed e.g. species that need warmer temperatures may spread further as the conditions they thrive in exist over a wider area. Other species ay become less widely distributed e.g. species that need cooler temperatures may have smaller ranges as the conditions they thrive in exist over a smaller area. This can reduce biodiversity due to extinction
How are scientists collecting data about the environment (collecting evidence)?
Using satellites to monitor sow and ice cover, and to ensure the temperature and to measure the temperature of the sea surface. Also recording the temperature and speed of the ocean currents to try and detect any changes. Automatic weather stations are constantly recording atmospheric temperatures.
How can this data be useful?
Only if it covers a wide enough area and a long enough time scale
What is fermentation?
Fuels can be made by fermentation of natural products, waste products can often be used. It’s when bacteria or yeast break sugars down by anaerobic respiration
How is ethanol made?
Yeast makes ethanol when they break down glucose by anaerobic respiration
What is the equation for this?
Glucose = ethanol + carbon dioxide + energy
How is ethanol made (process)?
Sugar cane juices can be used or glucose can be derived from maize starch but the action of carbohydrase (an enzyme), the ethanol is distilled to separate it from the yeast and remaining glucose before its used
How is ethanol used?
In some countries e.g. brazil, cars are adapted to run on a mixture of ethanol and petrol know as gasohol
What is biogas made of?
About 70% methane and 30% carbon dioxide. Lots of different microorganisms are used, they ferment plant and anima waste which contains carbohydrates. Sludge waste from e.g. sewage works or sugar factories is used to make it on a large scale
Where and how is biogas made?
In a fomenter called a digester or generator. The generators need to be kept at a constant temperature to keep the microorganisms respiring.
What are the two types of biogas generators?
Batch generators and continuous generators
How is biogas stored?
It cant be stored as a liquid as it needs a too high pressure, so it has to be used straight away-for heating, cooking, lighting or to power a turbine to generate electricity
As well as large scale biogas generators, what are small biogas generators being used for?
To make enough gas for a village or a family to use in their cooking stoves and for heating and lighting
What else can be digested by bacteria to produce biogas?
Human waste, waste from keeping pigs and food waste
What are the by products used for?
To fertilise crops and gardens
What are the two main types of biogas generator?
Batch generators and continuous generators
What are batch generators?
They make biogas in small batches. They’re manually loaded up with waste, which is left to digest, and the by-products are cleared away at the end of each session
What are continuous generators?
They make biogas all the time. Waste is continuously fed in, and biogas is produced at a steady rate. Continuous generators are more suited to large-scale biogas projects
What does any type of generator need to have?
An inlet for waste material to be put in, an outlet for the digested material to be removed through and an outlet so that the biogas can be piped to where it is needed
What are the four factors that need to be considered when designing a generator?
Cost, convenience, efficiency and position
Why does cost need to be considered?
Continuous generators are more expensive than batch ones, because waste has to be mechanically pumped in and digested material mechanically removed al the time
Why does convenience need to be considered?
Batch generators are less convenient because they have to be continually loaded, emptied and cleaned
Why does efficiency need to be considered?
Gas is produced most quickly at about 35 degrees C, if the temperature falls below this the gas production will be slower. Generators in some areas will need to be insulated or kept warm, e.g. by solar heaters. The generator shouldn’t have any leaks or gas will be lost
Why does position need to be considered?
The waste will smell during delivery, so generators should be sited away from homes. The generator is also best located fairly close to the waste source
Why are biofuels a greener alternative to fossil fuels?
They are carbon neutral, the carbon dioxide released into the atmosphere was taken in by plants which lived recently
Why is it good that these fuels don’t produce significant amounts of sulfur dioxide or nitrogen oxides?
Because sulfur dioxide and nitrogen oxides cause acid rain
Why is it good to burn methane as a biogas?
It’s a greenhouse gas and is one thats responsible for global warming. Its given off from untreated waste, which may be kept in farmyards or spread on agricultural land as fertiliser. Burning it as biogas means its not released into the atmosphere
Why is the raw material good to use?
Its cheap and readily available
Why is the digested material good to use?
It’s a better fertiliser than undigested shit-so people can grow more crops
How are biogas and biogas generators better for humans?
In some developing rural communities women have to spend hours each day collecting wood for fuel, biogas stops this. The generators act as a waste disposal system, getting rid of human and animal waste that’d otherwise cause disease and polluting water supplies
What are three different ways that the efficiency of food production can be improved?
Reducing the number of states in the food chain, restricting the energy lost by farm animals and developing new food sources like mycoprotein
How does reducing the number of stages in the food chain improve the efficiency of food production?
Theres less energy and less biomass when moving up a stage in a food chain, for a given area of land you can produce a lot more food by growing crops rather than by having grazing animals as you’re reducing the number of stages in the food chain, only 10% of what beef cattle eat becomes useful meat for people to eat. However people don’t need to eat a varied diet to stay healthy and theres still a lot of demand for meat products. Also some land is unsuitable for growing crops and animals like sheep and deer might be the best way to get food from the land
How does restricting the energy lost by farm animals improve the efficiency of food production?
In civilised countries animals are intensively farmed, kept close together indoors in small pens so they’re warm and can’t move, saves them wasting energy on movement, stops heat loss, makes transfer of energy from the animal feed to animal more efficient, they grow faster on less food. Makes it cheaper for farmer and us when animals are on supermarket shelves
What is mycoprotein?
It means protein from fungi
What is mycoporotein used for?
To make meat substitutes for vegetarian meals e.g. Quorn
What is the main source of mycoprotein?
A fungus called Fusarium
How is the fungus grown?
In fermenters using glucose syrup as food. The glucose syrup is obtained by digesting maize starch with enzymes. The fungus respires aerobically, so oxygen is supplies together with nitrogen (as ammonia) and other minerals. The mycoprotein is then harvested and purified
Why is the fermenter initially sterilised using steam?
Its important to prevent other microorganisms growing in the fermenter. The incoming nutrients are heat sterilised and the air supply is filtered
What are the advantages of using mcoprotein?
In developing countries its difficult to find enough protein. Meat is big source of protein, animals need lots of space to graze, grass etc Mycoprotein grown in a fermenter is efficient way of producing protein to feed people and they grow very quickly and don’t need much space and can even feed on waste material that would be no good for feeding animals
Why is there a growing demand for organic meat?
Some people think that forcing animals to live in unnatural and uncomfortable conditions is cruel. This means that the animals won’t have been intensively farmed.
What happens due to the crowded conditions on factory farms?
It creates a favourable environment for the spread of diseases, like avian flue and foot-and-mouth disease
How do they try to prevent these diseases?
Animals are given antibiotics. When the animals are eaten, these can enter humans, allowing microbes that affect humans to develop immunity to those antibiotics-so they become less effective as human medicines
How does intensive farming cause global warming?
The animals need heat so this means burning fossil fuels which wouldn’t be happening if the animals were in the natural environment
How does food distribution cause problems?
Some food products have lots of food miles, transported a long way from where they’re produced to where they’re sold. Can be expensive and also bad for environment as planes, ships and trucks all burn fossil fuels, releasing CO2 and contributing to global warming
What is an example of this?
Some green beans bought in the UK have come from Kenya
Why are fish stocks declining?
Because we’re fishing too much, meaning less fish for us to eat, the oceans food chains are affected and some species of fish may disappear altogether in some areas
How do we fix this problem?
We need to maintain fish sticks at a level where the fish can continue to breed.
What is sustainable production?
Having enough food without using resources faster than they renew
Wha are the different ways that fish stocks can be maintained?
Fishing quotas and net size
What are fishing quotas?
There are limits on the number and size of fish that can be caught in certain areas. This prevents certain species from being overfished
What is net size?
Different limits of the mesh size of fish nets, depending on whats being fished. This is to reduce the number of unwanted and discarded fish e.g. shrimp when they’re catching cod. Using a bigger mesh size will let the unwanted species escape and also the younger fish will slip through the net so they can reach breeding age
