B1 Topic 3

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What are drugs?
Chemical substances that affect the central nervous system. They cause changes in psychological behaviour and can be addictive. Drugs can be medically useful like antibiotics e.g. penicillin but many are dangerous if misused.
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What are prescription drugs?
Drugs that can only be obtained when prescribed by a doctor, but some medical drugs can be bought over the counter.
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What is drug addiction?
When someone has a physical need for a drug & if they don't get it they get withdrawal symptoms. Caffeine can be addictive and withdrawal symptoms include irritability and shaky hands. Rehabilitation is used for drug addicts to overcome an addiction.
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What is tolerance to drugs?
When the body gets used to the drug and needs a higher dose to receive the same effect. This happens with both legal drugs e.g. alcohol and illegal drugs e.g. heroin.
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Effect of depressants:
(alcohol) they decrease activity in the brain which slows response of the nervous system, causing slow reactions and poor judgement of speed and distances (e.g. why drink driving is dangerous).
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Effect of stimulants:
(nicotine, caffeine) increases activity in brain by increasing neurotransmisson at synapses. This increases speed of reactions which reduces reaction time. Makes you feel alert and awake. Used to treat depression.
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Effect of painkillers:
(morphine) blocks nerve impulses from pain receptors to decrease feeling of pain.
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Effect of hallucinogens:
(LSD) change in perception and distorted senses by altering pathways nerve impulses travel along. Example effect of LSD: colours seem brighter, hard to distinguish between real and not real.
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Experiment to measure reaction time:
Someone holds a ruler vertically between the thumb and forefinger of another person. They drop it with no warning and the other person has to catch it. Reaction time is measured in how far down the ruler is caught.
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Effects of smoking:
Dangerous in pregnancies-smoke contains carbon monoxide which combines with haemoglobin in red blood cells so they carry less oxygen which deprives the foetus of oxygen and makes the baby underweight.
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More effects of smoking:
Cancer - smoke also contains carcinogens like tar which lead to lung cancer, 90% of lung cancers are associated with smoking (& passive smoking). Addiction-cigarettes contains the drug nicotine which makes them addictive.
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Short-term effects of alcohol:
Alcohol is a depressant so your reactions are slowed. Being drunk also causes blurred vision and lower inhibitions which may lead to people behaving abnormally and taking more risks.
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Long-term effects of alcohol:
Alcohol is poisonous-the liver normally breaks down toxic alcohol & makes it harmless, but regularly drinking a lot makes liver cells die, forming scar tissue that blocks blood flow (cirrhosis) which means dangerous substances build up & cause damage
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More long-term effects:
Excessive drinking could also cause brain damage.
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How can organ transplants cure diseases?
If an organ is severely damaged by (e.g. from cirrhosis) an organ from a living donor (or someone recently brain dead) can replace it, e.g. if someone has a kidney problem the donor would donate one of their kidneys as they can live with only one.
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What is the NHS system for organ donation?
Joining the donor register shows you're willing to donate, but doctors still need consent from your family. Some say it should be easier to donate & instead should have an opt-out system where anyones organs can be used unless they say otherwise.
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What reasons make people less likely to receive an organ transplant?
Obesity-people have a higher risk of dying after surgery so may have to lose weight before they're considered for a transplant. Alcohol damage-people with liver damage from excessive drinking won't be considered until they stop drinking.
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Opinions on transplants:
Some people believe people that have harmed their own organs shouldn't be allowed a transplant over those who have an illness. But, transplant guidelines aren't based on who would 'deserve' a transplant but on who will most benefit from one.
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What are pathogens?
Microorganisms that cause disease. Examples are bacteria, protozoa, fungi and all viruses. They can spread through water, food, air, contact, body fluids and animal vectors.
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Spread of pathogens in water:
Drinking or bathing in dirty water can make you pick up pathogens. e.g. cholera is a bacterial infection that causes diarrhoea and dehydration, it's spread when drinking water is contaminated with the diarrhoea of other sufferers.
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Spread of pathogens in food:
Pathogens are also picked up by eating contaminated food. e.g. salmonella bacteria cause food poisoning and are found in food that has been kept too long or not cooked properly.
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Spread of pathogens in air:
Airborne pathogens are carried in the air in droplets produced when you cough or sneeze so other people can breathe them in. e.g. the influenza virus that causes flu is spread this way.
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Spread of pathogens in contact:
Some are picked up by touching contaminated surfaces including the skin. e.g. athletes foot is a fungus which makes skin itch and flake off, it's most commonly spread by touching the same things as an infected person like shower floors and towels.
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Spread of pathogens in body fluids:
Pathogens can be spread by blood (e.g. sharing needles to inject drugs), breast milk (breast feeding), and semen (through sex). e.g. the HIV virus that causes AIDS is spread by body fluids.
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Spread of pathogens in animal vectors:
Anopheles mosquito is a vector - it carries the protozoan that causes malaria and spreads the disease by biting other organisms. House flies are vectors that carry bacterium that causes dysentery and spread the disease by carrying bacteria onto food.
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How does the skin (physical barrier) stop pathogens entering the body?
Undamaged skin is a very effective barrier against microorganisms, and if it gets damaged, blood clots quickly to seal cuts and keep microorganisms out.
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How does the respiratory system (physical barrier) stop pathogens entering the body?
The whole respiratory tract (nasal passage, trachea, lungs) is lined with mucus and cilia. The mucus catches dust and bacteria before they reach the lungs and the cilia push the gunk-filled mucus away from the lungs.
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How do the eyes (chemical barrier) stop pathogens entering the body?
Eyes produce (in tears) a chemical called lysozyme which kills bacteria on the surface of the eye.
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How does the stomach (chemical barrier) stop pathogens entering the body?
If you eat food that contains pathogens, most will be killed by the hydrochloric acid in the stomach.
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How do plants use chemicals to defend themselves from pathogens?
Chemicals have antibacterial effects for protection. Humans use these e.g. tea tree is a big Australian shrub that makes oil to kill bacteria, before indigenous people used leaves in traditional medicine, now purified oil is used in facial cleansers.
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What are antiseptics?
Chemicals that destroy bacteria & stop them growing. Used outside the body to clean wounds & surfaces, prevent infection rather than treat it. Household products have antiseptics (bathroom cleaners). Used in hospitals to prevent infection spreading.
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What are antibiotics?
Drugs taken as a pill or injected to treat patients already infected with bacteria or fungi inside the body. Antibiotics don't destroy viruses e.g. flu and cold viruses. Two types - antibacterials and antifungals.
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Antibacterials:
Antibacterial antibiotics (e.g. penicillin) treat bacterial infections by killing bacteria or stopping them growing. But bacteria can evolve resistance to certain antibacterial antibiotics which means the antibiotics won't work anymore.
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Antifungals:
Antifungal antibiotics (e.g. nystatin) are used to treat fungal infections and work by killing fungi or stopping them growing.
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How can bacteria become resistant to antibiotics?
Bacteria can mutate & become resistant to some antibiotics so if you have an infection the resistant bacterias won't be killed. These bacterias reproduce & cause serious infections that antibiotics can't treat (e.g. MRSA). Drug misuse is also a cause
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Practical to investigate antibiotics and antiseptics?
Pour hot jelly into a petri dish, when it's set transfer bacteria to the culture medium. Take 3 paper discs, one soaked in antibiotic, another in a different antibiotic & the last in sterile water. Put the discs onto the jelly. Repeat with antiseptic
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What results will you see after the experiment?
After leaving it at 25 degrees for a day, a lawn of bacteria will show. Where it didn't grow is called the inhibition zone and the bigger it is the more effective the antibiotic. Control variables: temperature, disc size, concentration of antibiotics
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Food chains:
Sun is the source of energy for nearly all life on earth. Plants convert some of it into glucose, an animal eats the plant and gets energy from it, some it uses and some is stored. Then a big animal eats it and gets the stored energy.
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What uses up energy in each stage of a food chain?
Respiration, movement and heat from surroundings use up an organisms energy-especially in mammals and birds as they must stay at a constant temperature. Material & energy are lost in droppings also. Usually only 5 trophic levels are in a food chain.
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Pyramids of biomass:
Biomass is how much creatures weigh at each level of a food chain put together. A pyramid of biomass shows how much energy there is at each stage in the food chain. Each level you go up on a pyramid, the mass of organisms goes down as energy is lost.
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What is a parasite (parasitism)?
A parasite is an organism that lives in or on a host. They take food from the host and give nothing back which often harms the host. A parasite may be a plant or an animal.
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Fleas:
Insects that live on the fur and bedding of animals & humans. They feed by sucking blood of their hosts and reproduce quickly. The hosts gain nothing.
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Head lice:
Insects that live on human scalps, they feed by sucking blood and make the persons head itch.
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Tapeworms:
Attach to the intestinal wall of their hosts & absorb nutrients from the host which causes them to suffer malnutrition.
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Mistletoe:
A parasitic plant that grows on trees and shrubs. It absorbs water and nutrients from its host which can reduce the host's growth.
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What is mutualism?
A relationship where both organisms living closely benefit.
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Oxpeckers:
Birds that live on the back of buffalos. They eat pests on the buffalo like ticks and maggots which gives them food & gets rid of parasites from the buffalo, they also alert the animal of predators nearby.
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Cleaner fish:
Cleaner fish eat dead skin and parasites off larger fish. In return they get a source of food and avoid being eaten by the bigger fish.
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Nitrogen-fixing bacteria in legumes:
Most plants rely on nitrogen-fixing bacteria in the soil to get nitrates. Leguminous plants (beans, peas) carry the bacteria in nodules in their roots. The bacteria get a supply of sugar from the plant and the plant gets nitrates from the bacteria.
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Chemosynthetic bacteria in deep-sea vents:
Some chemosynthetic bacteria live in giant tube worms or the gills of molluscs in deep-sea vents. The tub worms supply the bacteria with chemicals from seawater which the bacteria turn into food for themselves and the host worms.
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Why is the human population increasing?
Modern medicines stopped widespread death from disease. Modern farming methods also now provide food for more people. More humans=greater impact.
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What are the potential issues of an increase in population?
Raw materials including non-renewable energy resources are being used up. Loads of waste and pollutants are being produced including phosphates (e.g. detergents), nitrates (e.g. fertilisers) and sulfur dioxide (e .g.from coal-burning power stations).
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How do fertilisers help crops?
They contain nitrates which are essential to modern farming and without them crops wouldn't grow as well and food yields would be down. This is because crops take nitrates from the soil which need to be replaced.
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How do fertilisers harm water life?
Some of the rich fertiliser gets into rivers, lakes and seas which happens when too much fertiliser is applied and rain washes it away. Eutrophication is the result where too many nitrates cause a sequence of mega-growth, mega-death and mega-decay.
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What is eutrophication?
Excess nitrates from fertilisers cause a bloom in algae in the waters surface. This blocks out sunlight so deeper plants can't photosynthesise and die. Increase in microbes as they feed on the dead plants and take oxygen so fish die from lack of it.
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What practical shows the effect of pollutants on plant growth?
Put cotton wool soaked with water in a jar and put 20 cress seeds on top (control variable). Do the same with another jar but soak the wool in pollutants and seal the jars with lids. After 5-7 days record the length of the shoots.
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What happens if we don't recycle?
Waste is produced in landfill sites and some of this waste is toxic which means the land is polluted. More materials have to be produced or extracted to make new products which uses up more resources and energy.
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Recycling metals:
Metals are extracted from ores (e.g. aluminium from bauxite) but metal ores are limited. Mining and extracting takes lots of energy mostly from fossil fuels which releases CO₂. Recycling uses less resources and produces less CO₂.
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Recycling paper and plastics:
Paper comes from wood which means cutting down trees, recycling prevents deforestation and uses much less energy than making new paper. Plastics come from crude oil so recycling conserves oil resources. They decompose slowly so fill up landfill sites
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What are problems with recycling?
Recycling uses energy for collecting, sorting etc. & some waste materials are time-consuming to sort e.g different plastics. Equipment for recycling is expensive. Sometimes quality of recycled materials isn't as good as new ones.
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What waste is produced by the UK?
England and Wales produce over 100 million tonnes of waste a year. Amount of waste recycled in UK is increasing. New laws introduced in UK and EU to increase recycling e.g. in 2015 EU law required cars were made of 95% recyclable materials.
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Indicator species for water pollution:
Stonefly larvae and freshwater shrimp indicate water pollution as they're sensitive to concentration of dissolved oxygen, they indicate water is clean. Blood worms and sludgeworms indicate a high level of pollution.
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Indicator species for air pollution:
Monitored by looking at lichen as they're sensitive to levels of sulfur dioxide. The amount of lichen will indicate how clean air is, if there are a lot then it is clean. Blackspot fungus is found on rose leaves and indicates clean air.
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How do non-living indicators show pollution levels?
Dissolved oxygen metres & chemical tests measure concentration of oxygen in water to show changing levels of water pollution. Electronic metres & laboratory tests measure the concentration of sulfur dioxide in air to show changing air pollution level
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The carbon cycle:
The only thing that removes CO₂ in the atmosphere is photosynthesis. Eating passes carbon compounds in plants to animals in food chains. Plant & animal respiration put CO₂ back in the atmosphere.
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More on the carbon cycle:
Plants and animals die and decay and are broken down by bacteria and fungi which releases CO₂ back in the air by respiration. Fossil fuels are burned which again releases CO₂.
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How are nutrients recycled?
Plants take carbon, oxygen, hydrogen and nitrogen from soil or air and turn them into complex compounds. These elements are returned to the environment in waste products made by organisms & when they die. All important elements are recycled.
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Uses of nitrogen:
Atmosphere contains 78% Nitrogen and it is unreactive so can't be used by plants or animals. It is needed for making proteins for growth.
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The nitrogen cycle:
Nitrogen in air needs to be turned into nitrogen compounds e.g. nitrates for plants to use it so they can make proteins. Animals can only get proteins by eating plants. Decomposers in soil break down dead plants and animals.
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More on the nitrogen cycle:
Decomposer bacteria turn proteins and urea into ammonia. Other soil bacteria called nitrifying bacteria convert ammonia into nitrates which can be taken up by plants so is recycled.
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What is nitrogen fixation?
The process of turning N₂ from air into nitrogen compounds in soil which plants can use.
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What two ways can nitrogen fixation occur?
Lightning-there's enough energy in a bolt of lightning to make nitrogen react with oxygen to make nitrates. Nitrogen-fixing bacteria in roots and soil.
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What are the four type of bacteria involved in the nitrogen cycle?
Decomposer bacteria-decompose proteins & urea into ammonia. Nitrifying bacteria-turn ammonia in decaying matter into nitrates. Nitrogen-fixing bacteria-turn atmospheric N₂ into nitrogen compounds . Denitrifying bacteria-turn nitrates into N₂ gas.
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Where does nitrogen-fixing bacteria live?
The soil or nodules on roots of legume plants (e.g. peas and beans). This is why legume plants are good at putting nitrogen back into the soil. The plants have a mutualistic relationship with the bacteria.
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Card 2

Front

What are prescription drugs?

Back

Drugs that can only be obtained when prescribed by a doctor, but some medical drugs can be bought over the counter.

Card 3

Front

What is drug addiction?

Back

Preview of the front of card 3

Card 4

Front

What is tolerance to drugs?

Back

Preview of the front of card 4

Card 5

Front

Effect of depressants:

Back

Preview of the front of card 5
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