gcse-core-biology-revision-guide

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GCSE Science Revision Page 1 BIOLOGY

B1a 1.1 Responding to Change It is the nervous systemthat enables you to react to your surroundings and co-

ordinates your behaviour

The nervous system carries electrical signals, orimpulses, at fast speeds that allowyou to react to surroundings very quickly

Controlling many of your bodys processes are chemical substances calledhormones, which are made and released, orsecreted, by special glands

Any changes in the surroundings are called stimuli and are picked up by specialisedcells called receptors. These are usually clustered together in special senseorgans, such as your eyes and skin

Once a sensory receptor picks up a stimulus, the information is sent as an electricalimpulse along special cells called neurones, which are collected in bundles callednerves. The impulse travels until it reaches the central nervous system (CNS),made up of the brain and spinal cord

The cells which carry impulses from sense organs to the CNS are sensory

neurones The brain processes the information it is given and sends impulses out along special

cells, which carry impulses from the CNS to the rest of your body. These cells arecalled motor neurones and they carry impulses to make the right bits of your body the effector neurones respond

Effector organs are muscles or glands. Your muscles respond to the arrival ofimpulses by contracting. Your glands respond by secreting chemical substances

The way the nervous system works can be summarises by:receptor sensory neurone co-ordinator (CNS) motor neurone effector

B1aB1aB1aB1a 111 1 Co-ordination and Control

1.21.21.21.2 Respondingtochange1.31.31.31.3 Reflexactions

1.41.41.41.4 Themenstrualcycle

1.51.51.51.5 Controllingfertilityartificially

1.61.61.61.6 Controllingconditions


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B1a 1.2 Reflex Actions Automatic responses in your body happen when, for example, you touch something

hot or sharp and pull your hand away quickly before you even feel the pain. These

automatic responses are called reflexes Reflexes help all animals avoid danger because they happen so fast

Three types of neurone are involved in reflex actions:- sensory neurones- motor neurones- relay neurones, which connect the two above neurone types

An impulse passes from the sensory receptor along the sensory neurone, to theCNS. It then passes along a relay neurone, usually in the spinal cord, and straightback along the motor neurone. From there the impulse arrives at the effector organ,usually a muscle for a reflex. We call this the reflex arc

Your nerves are not joint together directly, but instead have junctions between themcalled synapses. The impulses have to cross this gap, but cannot leap it, so achemical message is released, which crosses the synapse and releases an electricalimpulse that travels along the relay neurone

Most reflex actions can be shown as:stimulus receptor co-ordinator effector response

B1a 1.3 The Menstrual Cycle Hormones control the activity of individual cells, and this is the case in a womans

menstrual cycle

The levels of hormones released by the brain and ovaries affect a womans body

The average length of the menstrual cycle is about 28 days:- A new egg matures for around 12 days

- After maturing for about 14 days, the egg is released, this is known as ovulation- The lining of the womb stays thick for several days after release- If the egg is fertilised by sperm, pregnancy takes place and the lining of the womb

protects the developing embryo and provides food- If the egg is not fertilised, the dead egg and womb lining are shed, this is the

monthly bleed, or the period

All of these changed happen because of hormones, made and secreted by thepituitary gland (a pea-sized gland in the brain) and the ovaries

The hormones also stimulate the ovaries to produce the female sex hormone, calledoestrogen

Also released from the pituitary gland, is a hormone called FSH which makes eggsmature in the ovaries and stimulates the ovaries to produce oestrogen

Oestrogen stimulates the lining of the womb to build up ready for pregnancy, andstimulates the pituitary gland to make another hormone, called LH

LH stimulates the release of a mature egg in the middle of the menstrual cycle

B1a 1.4 Controlling Fertility Artificially The contraceptive pill can be taken to control fertility oral contraceptives

The pill contains many female hormones, mainly oestrogen, which affect the ovariesand prevent eggs being matured and the ovaries from releasing them becausewithout mature eggs, you cant get pregnant

People who want to get pregnant but cant can now use science to do so eggs canbe removed from the body and fertilised with sperm outside the body, and reinserted


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B1a 1.5 Controlling Conditions Your bodys internal environment(i.e. the conditions inside your body) is very

important. Organs cannot work properly if it keeps changing, so many of the

processes taking place inside your body try to keep things as constant as possible.This balancing act is known as homeostasis

Water especially can move in an out of the body, but we can consume water via foodand drink

Temperature is another factor we need to control, as it is vital that we keep it at 37oCfor it is at this temperature that enzymeswork best. If your body temperature rises ordecreases just a few degrees, processes in cells will stop happening and you will die

We also need to control blood sugar levels

The pancreaskeep the glucose concentration in our blood constant for us

B1a 2.1 Diet and Exercise A healthy diet contains:

carbohydrates, proteins, fats, vitamins, minerals, fibre and water

When a diet is unbalanced, a person becomes malnourishedand you will end upwith deficiency diseases if you dont consume enough vitamins or minerals (e.g.Scurvy is the disease caused by a lack of Vitamin C)

Younger people need more energy than older people Males need more energy than women of the same age unless they are pregnant

The rate at which the chemical reactions in the cells of the body happen varies agreat deal between people. This rate is known as the metabolic rate, and theproportion of muscle to fat in your body affects this rate. Other factors which affectmetabolic rate include the amount of activity you do, as exercise increases yourmetabolic rate for a short time after youve even finished exercising, and somescientists think you can inherit metabolic properties from your parents

B1a 2.2 Weight Problems YourBMI orbody/mass index compares your height and weight in this formula:

The average BMI is between 20 and 30, but if yours is under 18.5 or over 35 thenyour health is at risk

Excess energy is stored as fat, and too much fat can make you obese

You can lose weight by eating less, especially less energy-rich foods, such as chips

Increasing your exercise periods will also help you to lose weight

In some parts of the world, there is a major lack of food, and people suffer fromstarvation, where you become so thin, and you muscles begin to wear away. Indeveloped countries, this problem happens if people have the mental disorderanorexia(loss of appetite) nervosa

B1aB1aB1aB1a 2222 Healthy Eating

2.12.12.12.1 dietandexercise

2.22.22.22.2 weightproblems

2.32.32.32.3 fastfood

BMI =weight

(height)2


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B1a 2.3 Fast Food The amount of, and type of, fat you have in your body also affects you cholesterol

levels

Cholesterol is a substance made in the liver, which is transported around the body inblood. It is needed to make cell membranes, sex hormones and other hormones

High levels of cholesterol increase your risk of getting heart disease

It isnt only the overall level of cholesterol in your body, there are two completelydifferent types oflipoproteins to take into account- low density lipoproteins(LDLs) are known as bad cholesterol, and raised levels

of these increase your risk of heart problems- high density lipoproteins(HDLs) are known as good cholesterol, and they

reduce your risk of getting heart disease

A good balance of HDLs and LDLs is important for a healthy heart

There are three main types of fat which affect your cholesterol:- saturated fatsincrease blood cholesterol levels, and are found in animal fats, like

milk, butter and cheese- mono-unsaturated fats have two useful effects. They reduce your overall

cholesterol levels and improve the balance between HDLs and LDLs. These fatsare found in foods like olive oil, peanuts and some margarines

- polyunsaturated fats are even better at reducing cholesterol levels and balancingLDLs and HDLs, and are found in foods such as sunflower oil and oily fish

Salt is needed, like fat, in your body to allow the nervous system to work

B1a 3.1 Drugs A drugis defined as a substance in which alters the way the body works. It can

affect your body, your mind or both

Most drugs, both recreational and medicinal originally come from natural substances,often plants

Caffeine, nicotine and alcohol (the chemical ethanol) are all legal drugs in the UK

Other drugs, such as cocaine, ecstasy and heroin are illegal Which drugs are legal and which are not vary between different countries

You can get addictedto drugs; because some drugs change the chemicalprocesses in your body making you so addicted. This is when you becomedependent on them, and cannot manage without it properly. When an addict tries tostop taking or using a drug, they suffer from withdrawal symptoms, which includesweating, pains, headaching and cravings for their drug

People often take recreational drugs because they make them feel good aboutthemselves

There is no drug without any risks attached

Cannabis has a label as a safe drug, but this is proven not to be the case

B1aB1aB1aB1a 3333 Drug Abuse

3.13.13.13.1 drugs

3.23.23.23.2 legalandillegaldrugs3.33.33.33.3 alcohol

3.43.43.43.4 smokingandyourhealth


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B1a 3.2 Legal and Illegal Drugs The most common drugs around are everyday drugs, such as caffeine

Many drugs used for medicinal purposes have no or little effect on your nervous

system, whereas all drugs which people use for pleasure affect your brain andnervous system, and these are the changes people enjoy taking drugs for

People might take drugs to help them cope with everyday life, such as alcohol,nicotine and caffeine. Few people who take these drugs would consider themselvesaddicts, but they also affect your brain

Some recreational drugs are far more harmful than others, but they are all dangerous

Legal recreational drugs include ethanol (alcoholic drinks), nicotine (cigarette smoke)and caffeine (coffee, tea and cola)

Illegal recreational drugs include cannabis, cocaine, heroin, ecstasy and LSD

Drugs can also be used for sporting purposes, as some drugs can enhance sportingperformance

B1a 3.3 Alcohol Alcohol is part of social life for some people

In small amounts, alcohol (containing the drug nicotine) is harmless, but largeconsumptions and binging on alcohol can be extremely harmful

Alcohol is poisonous but the liver can usually break it down, and get rid of it beforepermanent damage is done to your health

Alcohol can also affect your mind: when drunk, you make foolish decisions

Some people drink heavily for many years becoming alcoholics

Alcoholics may develop cirrhosis of the liver, which destroys your liver tissue, orthey can get liver cancerwhich spreads far quicker and can be fatal. Also, alcohol inextremely large quantities can be harmful to the brain, making it soft and pulpy and

stopping it from working, causing death Alcohol is linked to many other problems, the most common of which being drink-

driving. Driving under the influence is a top killer in the UK today. Also linked toalcohol is domestic violence

B1a 3.4 Smoking and Your Health Nicotineis the addictive substance found in tobacco smoke, and it makes people

feel calm, contented and able to cope. The number you need to smoke to get theseeffects tends to increase, so the number you smoke daily increases over the years

Taris the sticky black chemical in tobacco smoke that builds up in your lungs,turning them from pink to grey, and it makes smokers much more likely to developbronchitis. The build-up of tar in your lungs can also lead to the delicate air sacs in

the lungs breaking down, called emphysema, making the lungs less efficient Tar is also a majorcarcinogen (a cancer-causing substance)

Carbon monoxide is another substance found in cigarette smoke, which is a verypoisonous gas, picked up by your red blood cells. Carbon monoxide in cigarettesmoke affects pregnant women in particular. During pregnancy, a woman needsoxygen, not just for her own cells, but for her developing foetus as well

Mums who smoke when pregnant have an increased risk of having:- a premature birth (born too early, will struggle to survive)- a baby with a low birth mass (more at risk of developing problems)- a stillbirth (where the baby is born dead)


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B1a 4.1 Pathogens An infectious disease is caused by a microorganism entering and attacking your

body. They are infectious because people can pass them between one another

Microorganisms which cause disease are called pathogens

Common pathogens are bacteria and viruses

A bacterium is a tiny single cell, made up of cytoplasm surrounded by a membraneand a cell wall. The genetic information in bacteria cells is not held in the nucleus

Not all bacteria are harmful

Virusesare even smaller than bacteria, and are made up of a protein coatcontaining the genetic material

Bacteria and viruses cause disease by multiplying very rapidly:- Bacteria simply split in two and often produce toxins (poisons) affecting your body- Viruses take over your cells as they reproduce, destroying cells in the process

Ignaz Semmelweisspage 63

B1a 4.2 Defence Mechanisms

There are several ways in which people spread pathogens:- droplet infection, often when people talk or sneeze tiny droplets full of pathogensare expelled from your breathing system

- direct contact, through direct contact of the skin, such as impetigo and certainsexually transmitted diseases, e.g. genital herpes

- contamination infection, eating and drinking contaminating goods, e.g. raw meat- through a break in skin, some pathogens can enter your body through cuts and

scratches and needle punctures, e.g. HIV/AIDS or hepatitis

Your body has its own defence mechanisms, for example when you cut yourself, youbleed, but the platelets quickly form a clot which dries into a scab

Your breathing system in particular is vulnerable, as every time you breathe youdraw in thousands of pathogens from the air although your breathing organs

produce mucus, a sticky substance, to trap the pathogens If a pathogen gets into your body past these defence mechanisms, your second line

of defence are the white blood cells of yourimmune system. The white blood cellshelp in a number of ways (see table on next page):- some produce antibodieswhich target bacteria or viruses- some produce antitoxins which counteract the toxins released by pathogens- some white blood cells ingest (take in) the pathogens and destroy them

B1aB1aB1aB1a 4444 Controlling infectious diseases

4.14.14.14.1 pathogens

4.24.24.24.2 defencemechanisms

4.34.34.34.3 usingdrugstotreatdiseases

4.44.44.44.4 changingpathogensandmutation

4.54.54.54.5 developingnewmedicines

4.64.64.64.6 pathogenimmunity


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B1a 4.3 Using Drugs toTreat Disease When we have infectious

diseases, we takemedicines, but often theydont destroy pathogens,they simply ease thepain, e.g. aspirin

Drugs which do killdisease-causing bacteriaare called antibiotics

Alexander Flemingdiscovered penicillinafter he came back froma holiday to discover thatthe mould growing on hisplates had killed thebacteria growing on them

It was Ernst ChainandHoward Floreywho firstput penicillin into practice

Antibiotics work by killing the bacteria whilst inside your body, and can be used tocure diseases such as plague and TB

Antibiotics have no effect whatsoever on viruses, as viral pathogens work inside yourbodys cells, making it hard to find treatments which will kill the virus and leave yourcells in tact

B1a 4.4 Changing Pathogens and Mutation Not all bacteria are killed when you take an antibiotic. The ones that remain have

naturally mutated and so are not affected by the antibiotic

If antibiotics do not kill a bacteria, they are resistantto that antibiotic

MRSAcame about due to resistance of antibiotics where these resistant bacteriaare carried around hospitals easily by doctors and nurses travelling from patient topatient

An outbreak of a disease which affects people on a major scale is an epidemic,usually affecting a single country

A pandemiccan affect several countries

The flu pandemic between 1918 and 1919 killed between 20 and 40 million people,

and this came about from cell mutation

B1a 4.5 Developing New Medicines When developing new medicines, scientists must keep in mind that they should be:

- effective, as in it will cure the disease or prevent the disease- safe, it should not be toxic (poisonous) and there shouldnt be any unacceptable

side effects- stable, it should be able to be used for quite some time and stored for some time- successfully taken into and removed from your body, the medicine must be

able to reach the desired destination and your body must be able to remove it onceit has done its work


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B1a 4.6 Pathogen immunity Every cell has unique proteins on its surface called antigens, and antigens on the

microorganism which get inside your body differ from those on your cells, which is

how your immure system recognises they are different Your white blood cells appear to remember the pathogens they destroy and so can

make the antibodies again very quickly should they encounter that particularpathogen again this is called being immuneto a disease

Immunisationcan happen through vaccination, where a tiny amount of the diseaseyou are being immunised against is injected into your body, so that your shite bloodcells can make the appropriate antibodies

No medicines are risk-free, including medical vaccines

B1b 5.1 Adaptation in Animals Living creatures have special features, oradaptations, which help them to survive in

certain conditions

Animals have adapted to live in extreme climates. The amount of heat you lose isclosely linked to your surface area : volume ratio (SA:Vol)

Some animals have fat layers which provide warmth as well as a food supply

Some animals are camouflagedto protect them from predators

Certain creatures have adapted to live in dry and hot climates, such as large ears

Other adaptation examples include a camels feet. The size of them is so importantbecause it stops them from sinking into the sand

B1b 5.2 Adaptation in Plants There are some plants which live in desert conditions which need to prevent water

loss, and they do this by controlling the SA:Vol as well as curling their leaves

Controlling the transpiration streamis important in plants

Many plants store water in their tissues to prevent water loss. Plants which storewater in their fleshy leaves are called succulents

Plants like cacti have adapted by having vicious thorns. Other plants avoid beingeaten by having poisonous chemicals and unpleasant tastes

B1B1B1B1b 5b 5b 5b 5 Adaptation to Environment

5.15.15.15.1 adaptationinanimals

5.25.25.25.2 adaptationinplants

5.35.35.35.3

competitioninanimals

5.45.45.45.4 competitioninplants


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B1b 5.3 Competition in Animals Animals best adapted to their environment are most likely to succeed in competition

Animals compete for many things, including water, territory and mates. Animals

which eat a wide range of plants are most likely to survive, as picky eaters will die ofstarvation if their food supply runs out

Animals try to avoid competition with others as best as they can

The best adapted creatures are those who find it easier to find food and a mate, andthese are the most likely to succeed in competition

Although it is hard to avoid competition, many animals attempt to do so by setting upa territory, but this can also encourage disputes

B1b 5.4 Competition in Plants Plants compete for light, water and nutrients from the soil

A successful competitor in plants is one which avoids competing with its own

seedlings Some plants might mark their territory by using mini explosions to disperse their

seedlings

B1b 6.1 Inheritance Animals inheritcharacteristics from the parents, as a result of theirgenetic

information passed onto you in the sex cells (gametes) from which you developed.This genetic information determines what you will look like

Inside the nucleus of all your cells there are chromosomesmade up ofDNA(deoxyribose nucleic acid). This is where the genetic information is actually stored

Each of your chromosomes contains thousands ofgenesjoined together. These arethe units of inheritance

B1b 6.2 Different Methods of Reproduction There are two types of reproduction: asexualreproductionand sexualreproduction

Asexual reproduction involves one parent and the offspring are clones, where thegenetic material of the offspring is identical to that of the parent

Asexual reproduction is common in the smallest animals, plants and bacteria

With sexual reproduction, a male sex cell and a female sex cell must join, one fromeach parent. If you are the result of sexual reproduction, you will inherit geneticinformation from both parents, having some characteristics from different parents. Inanimals, the involved sex cells are called the ova(eggs single ovum) and sperm

The joining of two different genetic materials ensures variation in the offspring, unlikethe clones produced in asexual reproduction which is better for competition survival

B1B1B1B1b 6b 6b 6b 6 Variation and Inheritance

6.16.16.16.1 inheritance

6.26.26.26.2 differentmethodsofreproduction

6.36.36.36.3 cloning

6.46.46.46.4 geneticengineering


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B1b 6.3 Cloning Plants can be cloned via cutting, which simply involves taking a small piece of the

plant, and if it is grown under the right conditions, new roots and shoots should

develop Many growers now use hormone rooting powders to encourage the cuttings

Tissue culturecan also now be used, which is a more modern way of cloning plants

Cloning animals involves a verydifferent process:1 Divide each cell into several

individual cells2 Each cell grows into an

identical embryo in the lab3 Transfer the embryos into

their host mothers, whichhave been given hormones

to get them ready forpregnancy

4 Identical cloned calves areborn. They are not biologicallyrelated to their mothers

B1b 6.4 Genetic Engineering We can change organisms and give them characteristics

that we want them to have by genetic engineeringorgenetic modification.

To do this, we take a small piece of DNA, a gene, fromone organism, and transfer it to the genetic material of acompletely different organism. An example of this isgenetically modifying cells to make insulin go into someoneelses body. People with diabetes need supply of thehormone insulin

Genetic engineering can also help us medically in otherways. For example, if there is a mistake in your geneticinformation, you are said to have a genetic disease, andmany people hope that genetic engineering can fix this

The big drawback with genetic modification is that no onereally knows for sure what the long-term effects are inusing it


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B1b 7.1 The Origins of Life on our Planet Earth Millions of species roam the planet, but scientists believe around 4 billion species

have existed here at some stage, some of which have gone completely, othersleaving living relatives, other still standing strong

Fossils are the remains of plants or animals from many thousands or millions ofyears ago which are found in rocks

Fossils can be formed in a number of ways:

- Most were formed when harder parts of the animal or plant were replaced by otherminerals over long periods of time

- Some are formed when animals or plants do not decay when dead, often becausethe temperature is too low for decay to happen

B1b 7.2 Different Evolution Theories The theories ofevolutiontell us quite simply that different species have evolved

since simple life forms that once existed on our planet

Jean-Baptiste Lamarckwas a French biologist brought around the idea of afountain of life and his theory was that everything had evolved from primitive worms.This theory was named inheritance of acquired characteristics

Lamarcks theory had no evidence supporting it, and as a result fell

Our most modern theory began with the work ofCharles Darwin, who explains thatall living organisms have evolved from simpler life forms. This evolution has comeabout by a process ofnatural selection

The fossil recordshows us how species have evolved over time

B1b 7.3 Natural Selection Scientists use the process ofnatural selectionto explain todays variety of life

Whether it be from competition or adaptation for survival, natural selectiondetermines which species will survive and continue to breed

Natural selection is essentially survival of the fittest

A good example is a rabbit. With all-round eyesight, extremely sharp hearing and the

longest legs, they will be the ones most likely to escape a foxs clutches, and theseuseful genes will be passed onto their babies

Good characteristics can come about from mutations in genes, which sometimesare good and sometimes are bad good ones will improve an animals chance innatural selection

The main points of natural selection can be summarised by saying:mutation variation adaptation survival genes passes onto next generation

B1b 7.4 Extinction Of the 4 billion species estimated to have existed in the past, only a few million live

on today, the rest all died out they became extinct

B1B1B1B1b 7b 7b 7 b 7 Evolution

7.17.17.17.1 theoriginsoflifeonourplanetearth

7.27.27.27.2 differentevolutiontheories7.37.37.37.3 naturalselection

7.47.47.47.4 extinction


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The term extinctionmeans the permanent loss of all members of a species from theface of the Earth

A species may become extinct for several reasons. One is environmental factors. For

example, an organism best suited for hot climates wont survive well in a cold place they will be too cold, find it hard to eat and be too cold to breed. Environmentalchanges are the most common causes of extinction throughout history

Another reason is because of other organisms. When a new predatorturns up, itcan wipe out unsuspecting prey animals very quickly, because the prey animals haveno adaptations to avoid it.

Other organisms, i.e. microorganisms, can spread diseasesto the point of extinction

The other main reason is through competition, also caused by other organisms

B1b 8.1 The Effects of the New Population Explosion One thousand years ago, there were around 500 million people on this planet. Now

there are over 6 billion people

The ever-growing population has such a bad effect on our land and naturalresources

The growing population also means a vast increase in waste, both human bodily andrubbish from packaging, uneaten scraps and disposable goods. This large dumpingof waste makes the land unavailable for anything else and can cause seriouspollution, which is exceptionally bad for the planets atmosphere

B1b 8.2 Acid Rain and the Environment When fossil fuels are burned, carbon dioxide is released into the atmosphere as a

waste product. But this is not the only waste, sulphur impurities react with oxygengas to form sulphur dioxide gas. These gases pollute the air, and have devastatingeffects

All waste gases produced from burning fuel can cause serious breathing problems

Sulphur dioxide and nitrogen oxide gases dissolve in the rain and react with oxygenin the air to make the rain acidic acid rain

Acid rain can ruin buildings, homes, statues and habitats for animals and plants

B1b 8.3 Global Warming and Earth Normally the Earth radiates back much of the heat energy it absorbs from the Sun,

keeping the surface temperature acceptable for life. Now carbon dioxide andmethane are building up in the atmosphere, acting like a greenhouse around Earth

The greenhouse gases absorb much of the energy which is radiated away. It cantescape out into space. As a result, the Earth and its surrounding atmosphere arewarmer than they should otherwise be this greenhouse effect plays a part inglobal warming

B1B1B1B1b 8b 8b 8b 8 How people Affect the Planet

8.18.18.18.1 theeffectsofthenewpopulationexplosion

8.28.28.28.2 acidrainandtheenvironment

8.38.38.38.3 globalwarmingandearth

8.48.48.48.4 sustainabledevelopment

8.58.58.58.5 thefutureofourplanet-inourhands


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B1b 8.4 Sustainable Development We aim to improve the quality of our lives without risking the future of generations to

come, and this is sustainable development

An example of sustainable development is the replanting of trees as they are felledfor wood and paper, which not only provide a good resource for wood and paper, butalso continue to play home to animals and plants habitats

We can improve our planet by all switching to energy-efficient light bulbs in order tohelp reduce carbon dioxide levels in the atmosphere

We all need to make our houses more energy-efficient

B1b 8.5 The Future of Our Planet In Our Hands In the UK, we have two types of land: brown field sitesand green field sites. We

are able to build on both of these. When we build on a green field site, we build on anew piece of land. Brow field sites are places that have already been built on, so ifwe build on them, it may be refurbishments or it may be destroyed and rebuilt

Similar to green field sites are green belts, which we are not allowed to build on

Similar to green belts are SSSIs (Sites of Special Scientific Interest), which mayhave a unique or particularly interesting landscape, or be home to rare species ofplants or animals and need protecting

The idea of protected areas may benefit the atmosphere from pollution, as well asthe actual areas themselves

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