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Science B1 Topic 3
GCSE edexcel core science biology: problems and solutions to a changing environm
| Question | Answer |
|---|---|
| What is a drug? | A CHEMICAL substance that changes the way the body works- affecting the central nervous system and psychological behavior. |
| Describe the general effects of painkillers (with examples) | Painkillers are drugs that block nerve impulses carrying information to the brain so that we feel less pain. e.g. paracetamol, morphine. |
| Describe the general effects of hallucinogens(with examples) | Hallucinogens are psychoactive drugs that distort sense perception of stimuli. e.g. LSD. |
| Describe the general effects of stimulants(with examples) | Stimulants are drugs that increase the speed of reactions and neurotransmission at the synapse. e.g. caffeine, ecstacy. |
| Describe the general effects of depressants(with examples) | Depressants are drugs that slow down activity of neurones in the brain and reduce neurotransmission at the synapse. e.g. alcohol |
| What are the ways that drugs can be categorized? | 1) recreational and medicinal 2) legal and illegal |
| What affect do most drugs have on the body? | They cause a person to become dependent on the drug so that they feel that they can't function properly without it- as most drugs are addictive. |
| What is tar in cigarettes and what effects does it have? | Tar is a brown, sticky substance found in tobacco, which contains carcinogens that cause cancers in the lungs and mouth. It also paralyses cilia in the lungs and stains teeth. |
| What is carbon monoxide in cigarette smoke and what effects does it have? | It is a poisonous gas which bind irreversibly with haemoglobin in red blood cells, reducing how much oxygen can be carried by the blood. |
| What is nicotine in cigarettes and what effects does it have? | It is the addictive component that; * makes it hard for smokers to quit as without it they get withdrawal symptoms e.g. depression * increases levels of neurotransmitter dopamine which causes enjoyment |
| What is it hard to prove that smoking causes death? | Because it takes many years for smoking to cause death/ large impacts on health, and in this time people are exposed to many other substances, so it is hard to prove the correlation between the two. |
| Which studies relating to smoking and impacts on health are the best to give reliable evidence? | Long-term studies that look at individuals for many years, or studies that look at a large range of people are best, as they average out natural variation |
| What are some short term effects of alcohol? | * blurred vision & bad coordination * slows down reactions * lowers inhibitions so people take greater risks * large amounts lead to unconsciousness * slows down brain activity * death by choking on vomit |
| What are some long term effects of alcohol? | * cirrhosis of the liver (tissue is destroyed so that the liver can't function properly, can cause death) * brain damage, as it effects memory and learning * blood clots in the brain |
| What is a transplant? | where a healthy organ is taken from a donor and put into a patient to replace an organ that no longer works properly |
| What are scientific criteria, and how are they used? | Scientific criteria are standards that scientists use to decide who deserves the transplant. They base it on the likelihood of success; *if the patient & donor have similar tissues * are similar ages *live geographically close *how ill the patient is |
| What are ethical criteria, and how are they used? | Doctors also use ethical criteria (standards) to reach a fair (yet often controversial) decision. |
| What happens to alcohol abusers in relation to transplants? What are the arguments about this? | They may get cirrhosis of the liver. Some hospitals only give them the transplant if they stay off alcohol for 6 months to make it worthwhile. - the disease isn't the person's fault, may die in that time - lifestyle is a choice, would waste money |
| What happens to obese people in relation to transplants? | The clinically obese may need a heart transplant. In some hospitals they only get the transplant if they stick to a weight loss diet |
| Why do scientists and doctors need criteria for transplants? | Because there is a small supply of organs and donors, but a large demand for them. |
| What are pathogens? | Microorganisms that cause infectious diseases e.g. bacteria, fungi, viruses, protozoan, protoctists |
| What are the 6 ways that pathogens are spread (and what are examples)? | *Water: cholera bacterium *Food: salmonella bacterium * Airborne: influenza virus *Contact: athletes foot fungus *Body fluids: HIV -> blood ->semen ->breast milk *animal vectors ->anopheles mosquito: malaria protozoan ->housefly: dysentry bacter |
| What are physical barriers and what are some examples in humans? | They stop pathogens entering the body *skin forms protective barrier *sweat glans make substances that kill pathogens *mucus traps microorganisms *cilia sweep mucus out of lungs |
| What are chemical defences and what are some examples in humans? | Chemicals that kill pathogens before they cause harm *tear glands produce tears contains lysozymes which kills microorganisms * hydrochloric acid in stomach kills harmful microorganisms |
| What are antiseptics? | Chemicals that kill microorganisms outside the body and prevent pathogens spreading and getting into open wounds (they are used around raw meat, toilets) |
| What are antibacterials? | Chemical substances produced by plants that prevent pathogens from causing damage |
| How do humans use antibacterials? | They use them for their antibacterial effect e.g. witch hazel in aftershaves prevents infection through cuts in the skin |
| What are antibiotics and what are the different types? | Chemical substances that prevent growth of bacteria and some fungi (not viruses)- they kill the pathogens but no the patient: -> antibacterials only affect bacteria (e.g. penicillin) -> antifungals only affect fungal infections (e.g nystatin) |
| How can bacteria become resistant to antibiotics (stopping)? | Bacteria show variation, so some are more resistant to certain antibiotics and it takes longer to kill them. If a patient stops taking antibiotics during their course, the resistant bacteria are left to reproduce and spread-that antibiotic cant be used |
| How can overusing antibiotics develop resistant bacteria? | Antibiotics kill many types of bacteria, not just the ones they are being used against. When the treatment stops, the resistant bacteria of all the different types of bacteria the antibiotic has affected are left |
| What is an example of a resistant bacterium? | MRSA |
| What is interdependence? | The dynamic (changing) relationship between living things |
| What are producers? | Organisms that make their own food e..g green plants use light energy for phorosynthesis |
| What are primary consumers? | Herbivores that eat the producers |
| What are the secondary consumers? | Omnivores or carnivores that eat the primary consumers |
| What are food chains? | Chains that show what eats what |
| What are food webs? | Lots of food chains joined together to show the interdependence and feeding relationships |
| At each trophic level, what happens to the energy? | Some is lost to surroundings, used in respiration, lost in faeces, turned into biomass. Biomass is an organism's dry mass and is passed on to the next organism in the food chain |
| What limits the length of a food chain? | The fact that energy is lost at each level, so by the end there isn't enough energy to support another animal |
| WHat does a pyramid of biomass show? | The total mass of all the individuals in a population, put into a pyramid to show feeding relationships |
| What is parasitism? | Feeding relationships between two organisms where the parasite feeds off the host and benefits from it, but the host is damaged/ dies. |
| What are some parasitic relationships? | *flea:ectoparasite, sucks blood of host *headlice:ectoparasite, lives on scalps & bites host for blood *mistletoe:plant parasite, leaves photosynthesise but roots grow into the veins of host tree &absorb nutrients *tapeworm:absorbs nutrients from host |
| How are headlice and fleas adapted? | They have flattened bodies and claws to grip into host |
| How are tapeworms adapted? | They can self fertilise eggs, have large surface areas for absorbtion of food, can't be digested, hooks and suckers attach it to intestine |
| What is mutualism? | A relationship between two organisms where both benefit |
| What are some examples of mutualistic relationships? | *oxpeckers eat parasitic insects off skin of herbivores, so they are fed and the herbivore isn't so itchy *cleaner fish eat dead skin and parasites of skin of larger fish *nitrogen fixing bacteria *chemosynthetic bacteria |
| What is the relationship that nitrogen-fixing bacteria are involved in? | They are in mutualistic relationships with leguminous plants (plants with pods)- they live inside root legumes where they are protected from environment and given food, & they convert nitrogen in the air into nitrogen compounds for the plant to grow well |
| What is the relationship that chemosynthetic bacteria are involved in? | They are producers that are involved in a mutualistic relationship with giant tubeworms- who give them chemical substances for chemosynthesis, and the tubeworms feed of the substances made by the bacteria |
| Why is population growth happening? | Because of improved medicine, living conditions and food production |
| What issues does population growth cause? | * uses up lots of raw materials * burns more fossil fuels which produce pollutants (e.g. CO2 and SO2) * more food is needed, so more fertiliser is added which can cause eutrophication |
| What is eutrophication? | Farmers use lots of fertiliser, nitrates and phosphates dissolve in soil water, and if not used they are washed into streams. They cause rapid growth of algae, which block sunlight so plants in water die (less O2). Bacteria increase, less oxygen, fish die |
| What are indicator species? | Species that are particularly sensitive or tolerant to pollution, so their presence- absence can be used as a measure of pollution |
| What are some air quality indicators? | * black spot fungus- infection of roses killed by sulphur dioxide * lichens- mutualistic relationships between fungus and alga. Different lichens can tolerate different amounts of pollutants |
| What are some polluted water indicators? | Sludgeworms and bloodworms, both are adapted to living in oxygen-deprives water |
| What are some clean water indicators? | Freshwater shrimps and stonefly larvae- both need water with lots of oxygen |
| Why is recycling important? | AS we waste lots of raw materials and landfill sites take up land and cause pollution |
| What is recycling? | The process of taking materials out of waster and converting them into new materials |
| What are some examples of recycling? | Metal drink cans -> new cans/ car aprts Paper -> paper/ cardboard Plastic bottles->fleec clothing |
| What is the carbon cycle? | The movement of carbon through organisms |
| What are the processes involved in the carbon cycle? | Photosynthesis, respiration, eating, death, excretion, egestion, fossilisation, combustion |
| Name three ways tha nitrate concentrations can be increased in the soil. | * nitrogen fixing bacteria in roots nodules of leguminous plants turn nitrogen into ammonia for plants * nitrogen fixing bacteria in soil turn nitrogen into ammonia * lightning |
| What do denitrifying bacteria do? | They convert nitrates in the soil into nitrogen gas if the soil is waterlogged and is lacking in oxygen. |
| What are nitrifying bacteria? | They turn ammonia into nitrates in the soil. |
| Why is nitrogen important for organisms? | It is used to make proteins, but organisms can't use nitrogen from the air directly. |
| What is the word equation for photosynthesis? | carbon dioxide + water -> oxygen + glucose |
| What is the word equation for combustion? | hydrocarbon fuel + oxygen -> carbon dioxide + water |
| What is the word equation for respiration? | glucose + oxygen -> carbon dioxide + water |
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