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Bacteria Weight problems Antibiotics B1.1 Keeping Healthy Diet and exercise Pathogens and disease Immunity Defence mechanisms Diet and exercise •Carbohydrates •Proteins •Fats •Vitamins •Minerals •Water •Fibre Metabolic rate: Rate of chemical reactions in your cells Affected by... Gender, proportion of muscle to fat, exercise /activity, genetics How much energy do you need? Key words: •Males need more energy than females Deficiency diseases •Growing teenagers need more energy than the elderly Malnourished •If you exercise you need to eat more •Temperature has an effect – hotter then less energy spent warming up Weight problems Obesity • Excess energy is stored as fat • Some body fat is needed for cushioning and as an energy store • Can lead to arthritis, diabetes, high blood pressure, heart disease Inheritance: Affect metabolic rate, risk of heart disease, muscle:fat, cholesterol Cholesterol: Needed for cell membranes and hormones eating high fat food means a higher level of harmful cholesterol and heart disease. This can also be inherited so levels will be high regardless of diet Losing weight (mass) Take in less energy than you use • Reduce amount of food • Increase exercise Slimming groups provide support Pathogens and disease Pathogens: Microorganisms that cause disease Infectious: the microorganism can be passed on Semmelweis Many women used to die after childbirth ‘childbed fever’. He noticed doctors would go from dead body to baby delivery without washing hands. A doctor had a cut and died from the same symptoms. He told doctors to wash their hands but they were angry he was blaming them for deaths – they didn’t know about viruses /bacteria and thought it was God’s punishment to women Bacteria: Single-celled living organisms. Used in yogurts, medicine Reproduce asexually inside the body, produce toxins and damage cells Symptoms are your body responding to this viruses: Very small, cause diseases in every type of living organisms They take over body cells, damage and destroy them Defence mechanisms • • • • Droplet infection – mucus Direct contact – skin barrier Contaminated food and drink – stomach acid Break in the skin – scabs White blood cells of the immune system Ingest microorganisms Produce specific antibodies Produce antitoxins Antibiotics Painkillers relieve symptoms but do not affect the microorganism Antibiotics work inside the body to kill bacteria that cause diseases by damaging the bacterial cells – they don’t work on viruses as they live inside body cells Some bacteria may mutate by natural selection They are antibiotic resistant The flu virus mutates very easily so the immune system wont recognise it To reduce this we should... Only use antibiotics when necessary, treat with specific antibiotics, medical staff wash hands, isolate some patients, clean hospitals MRSA: a result of natural selection in hospitals where many bacteria and antibiotics used to treat Growing bacteria • Microorganisms can be cultured in the lab • A culture medium (agar) is given containing an energy source (carbohydrate) and minerals. They are kept warm and allowed oxygen to grow Safety: Bacteria may mutate so contamination must be avoided – e.g. From skin, air, water.. Petri dishes and agar must be strilised from an autoclave or using gamma radiation / UV Inoculate the plates – sterilise the loop, dip in suspension, zigzag then incubate Immunity • Antigens – unique proteins on a cell surface • White blood cells produce antibodies to join up with antigens on a pathogen • White blood memory cells – immunity Vaccination – dead or weakened version of the pathogen introduced to body so white blood cells can develop antibodies – immune e.g. MMR, tetanus, smallpox wiped out Vaccination debate: no medicine is risk free and some have rare side effects but it is important to vaccinate to protect the population from disease e.g. MMR, Whooping cough – parents told could be dangerous but the disease itself poses more risk – brain damage etc Exam Questions [6 marks] Reflex actions Responding to change Homeostasis B1.2 Coordination and Control Fertility Hormones and plant growth Hormones and menstrual cycle Responding to change • The nervous system carries impulses along neurons enabling you to react to your surroundings and coordinate your behaviour. Stimulus Change in the environment Receptor E.g. Eyes, skins, found in sense organs Sensory neuron CNS Brain and spinal cordcoordinates response Motor neuron Effector Muscles (contract) or glands (secrete) Reflex actions • Automatic responses important for survival • Similar response to a normal conscious action but involves a relay neuron in the spinal cord or unconscious area of the brain • It then travels to the conscious area so you know about the reflex - after it has happened Synapses Junctions between nerves Impulses cross the synapses Chemicals released into the gap between neurons Chemicals attach to the surface of the next neuron and set up a new electrical impulse • Sensory receptor --> sensory neuron --> CNS --> relay neuron (spinal cord) --> motor neuron -> effector 27 Hormones and fertility • Glands secrete hormones which are then carried around in the blood Menstrual cycle Brought about by hormones made and released by pituitary gland and ovaries Hormones: FSH -causes eggs to mature -Stimulates the ovary to produce oestrogen Oestrogen -Causes the lining of the uterus to develop -Inhibits FSH production -Stimulates the release of the mature egg Others: progesterone and LH 28 days: womb lining thickens, Eggs released from ovary after 14 days ovulation, If not fertilised, the womb lining and egg come out as a period Contraception Inhibits production of FSH so eggs don't mature in the ovaries Fertility treatments FSH used to stimulate eggs to mature and trigger oestrogen production IVF - eggs collected and fertilised in the lab then implanted Advantages - fewer children (cost), women freedom Disadvantages - expensive, multiple births, embryo use Homeostasis • Internal environment is maintained by homeostasis Controlling water and ions -Water moves in an out of body cells -taken in from food and drink -lost from breathing out, sweat and urine (salt lost here too) -Kidneys control this Controlling temperature -Core temperature 37C, enzymes work best -Sweat to cool down, shiver to warm up -Below 35C hypothermia risk - too high leads to heat stroke / heat exhaustion enzymes and cells don’t work properly Controlling blood glucose -Kept constant by hormones from pancreas Hormones and plant growth • Plants are sensitive, they need to grow the right way.. • Plant roots grow towards moisture and in the direction of force of gravity • Plant shoots grow towards light and against the force of gravity Phototropism – response of a plant to light Gravitropism/geotropism – response of a plant to gravity Auxin – hormone that controls responses of roots and shoots Using plant hormones – used as rooting powder or high doses as weed killers due to rapid uncontrolled growth The opposite occurs in the roots Exam Questions Legal and illegal drugs Drugs in sport Drugs B1.3 Medicine and Drugs Cannabis and hard drugs How effective are medicines Developing new medicines Developing new medicines A good medicine is: • Effective – prevent / cure a disease / ease symptoms • Safe – not toxic or unacceptable side effects • Stable – use the medicine in normal conditions and able to be stored • Successfully taken into and removed from body Developing drugs can take 12 years and cost around £350million They are tested on cells, tissues and organs before animal testing and human trials Placebo – pill that does not contain the drug Double blind trial – neither doctor or patient knows who has the real drug Thalidomide Used in 1950s as treatment for morning sickness Tests on pregnant animals not carried out until 1968 Affected fetuses – born with severe limb deformities How effective are medicines? Statins: drugs that lower cholesterol in the blood and stop the liver producing too much cholesterol. Patients should also have a healthy diet. This reduces the risk of heart disease Prescribed and non-prescribed drugs Prescribed drugs have been tested in double blind trials and many of the most effective ones come from living organisms. Non-prescribed drugs may not have been evaluated the same way due to expense. St John’s Wort is a non-prescribed herbal remedy for depression – it has been found to be an effective medicine and more effective than placebo Drugs Drug: alters the way the body works Legal: coffee, cigarettes, alcohol • Millions of people take these so health impact is much bigger than for illegal drugs Illegal: cocaine, ecstasy, heroin • Affect nervous system Cannabis: Trigger mental illness Higher risk of depression Gateway drug? Almost all heroin users were originally using cannabis – people in touch with drug dealers Withdrawal symptoms – cravings, aches, sweating etc Addiction: dependent – cant function without the drug. More and more is needed for same effects Addicts may turn to crime to fund drug habits, more likely to get STDs, mental / physical health problems Drugs in sport Random drugs tests. Athletes that are caught are banned. Some medicines contain banned substances so they need to be careful. Some drugs are found naturally in the body as levels vary it can be difficult to find cheaters Sport Drug type Why use them? Problems Bodybuilding Painkillers Compete when injured Exacerbates injury Archery Beta blockers Steady hands Insomnia, depression Cycling Erythropoietin More RBC - oxygen to legs Kidney disease Sprinting Anabolic steroids Muscle growth Sexual characteristic change Ethics: People should be able to do what they want with their body regardless of risk Only the richest / most sponsored people can cheat Desire to win and be the best Other athletes are using them Claim they didn’t know they were cheating, coaches gave them ‘supplements’ Exam questions [6 marks] [4 marks] Environmental change Competition in animals and plants Adaptation for survival Adapt and survive Adaptation in plants Adaptation in animals Adapt and survive Living organisms need to survive and reproduce • Plants need: light, carbon dioxide, water, oxygen, nutrients • Animals need: food, water, oxygen • Microorganisms needs depend - some are light plants, some like animals and some need no oxygen or light Extremophiles – organisms adapted to extreme environments. e.g. Bacteria can live at temperatures as low as -15 or up to 80C as their enzymes are adapted not to denature. How do you survive? • Each fig tree has its own type of pollinating wasp – the fig flowers are adapted to attract the specific wasp type. The wasps are adapted with specially shaped heads, ovipositors • Star nose mole reacts and eats prey within 230milliseconds - they are blind and need to eat their prey as soon as they touch it or it might escape • Venus fly traps have grow in bogs with little nutrients. Insects are attracted to their smell and colour, enzymes are digested and nutrients used Adaptation in animals Surface area: volume ratio • Mammals in a cool climate grow to a large size (e.g. Whales) to keep their ratio as small as possible to maintain body heat Cold Climates: Small surface area e.g. Ears Insulation – blubber (thick layer of fat under skin), fur coat Fat layer also provides a food supply during winter Dry climates Deserts may be hot in day and freezing at night. Lack of water Often active at night rather than day Can’t sweat or will lose water small – large surface area:volume to lose heat through skin Big ears- lose heat Thin fur, little body fat Camouflage : Important in predators and prey Dependent on environment (arctic hares brown in summer and white in winter) Adaptation in plants Water taken in through roots Stoma in leaves allow gases in and out for photosynthesis and respiration In dry climates: – very wide root systems – store water in leaves, stems or roots Surface area:volume ratio Curled leaves – traps layer of moist air, reduces surface area Thick cuticle – stops evaporation Or.. Broad leaves – large surface area to collect dew Epiphytes – in rainforests live high above ground and collect water and nutrients from the air Competition in animals and plants Animals • Food – more likely to be successful if eat a wide range. Competition between own species too, better adapted will survive • Territory – compete for best space/ area • Mate – males fight or display Success depends on adaptations ... Avoiding competition can also lead to success Plants • Light (photosynthesis) smaller plants may flower earlier in the year before the bigger plants to get more light • Water (photosynthesis) different types of roots – spread along surface or deep underground • Nutrients • Space (roots and light) Spreading seeds – sycamore, dandelion, Fruits, sticky Environmental change • Average temperature, wind, rainfall, light, pH, oxygen levels, other species, climate will affect where an organism lives • If any of these change the biodiversity can be affected • Bioindicators can be used to monitor change – lichen are sensitive to air pollution Changing birds of Britain Bird habitats and migration affected Dartford warblers are more common due to increased temperatures, but less common in Spain where it is now too warm Bees Disease (CCD) affecting honey bees Bees are important for pollination of plants – apples, raspberries, cucumbers etc Cause unknown – pesticides? Climate? Exam questions: [6 marks] Decay processes Carbon cycle B1.5 Energy in biomass Recycling organic waste Pyramids of biomass Energy transfers Pyramids of biomass • Biomass is the amount of living thing available to the next level in a food chain – the mass of material in living organisms • It is the total mass without the mass of water (dry mass in grams) • Pyramids of biomass show how much energy is available at levels in a food chain Energy transfers Much of the energy lost in: • Movement (muscles contracting) • Heat • Keeping a constant body temperature (energy needed to keep warm or cool down) • Waste (herbivores can’t digest all they eat, excess protein passed out as urea) 1110 KJ in heat loss 3060 KJ in food 1797 KJ in urine and faeces Decay processes Detritus feeders (e.g. Maggots, worms) start the process by eating dead animals and producing waste material Decomposers (microorganisms) digest everything, using some of the nutrients to grow and reproduce They produce waste products – CO2, water and nutrients This recycling means the soil contains mineral ions plants need to grow and cleans up dead organisms Conditions for decay: • Warm – Chemical reactions in microorganisms work faster when warm – Reactions slow down and stop if too cold, enzymes denatured if too hot • Moist – Easier to dissolve food, prevents drying out • Plenty of oxygen – Decomposers respire, need oxygen to release energy Uses: sewage treatment works, compost Carbon cycle The amount of carbon is fixed • Photosynthesis: green plants and algae remove CO2 from the atmosphere – passed on when plants are eaten Carbon dioxide + water glucose + oxygen • Respiration: living organisms use oxygen to break down glucose CO2 is a waste product. Decomposers respire too Glucose + oxygen carbon dioxide + water • Combustion: fossil fuels contain carbon , when we burn then CO2 is produced Fuel + oxygen carbon dioxide + water Recycling organic waste • Organic waste – (e.g. Vegetable peelings) doesn’t rot easily in landfill, it forms a liquid that can pollute waterways and methane gas which contributes to global warming Making compost: To speed up the process: • Mixing regularly helps oxygen get in • Warmer conditions (up to about 70C) • Moist conditions Methods: compost heap, black bag, compost bin, council composting Exam questions [2 marks] Genetic engineering Genetic and environmental differences B1.6 Variation Inheritance Types of reproduction Cloning plants Cloning animals Inheritance • Genetic information is in the nucleus of cells • Inside the nucleus are chromosomes made up of DNA – humans have 46 chromosomes (23 pairs) • Genes are a section of DNA and control enzymes and proteins made in your body • Genes are passed on to you in the sex cells (gametes) from your parents – they come in pairs Types of reproduction Sexual reproduction Asexual reproduction • Male sex cell and female sex cell • Risky as the two have to meet • BUT provides genetic variation important for survival • E.g. Mammals, birds • One parent • No genetic variation – clones • Cells of body reproduce asexually – divide in two for growth and repair • E.g. Bacteria, strawberries Advantages – allows evolution, variation, increases chances of species survival Disadvantages – need to find a partner, waste energy. Waste in producing gametes, slower Genetic and environmental differences Nature – genetic variety • E.g. Eye colour, gender, shape of nose Nurture – environmental variety • E.g. Scars, accents, drinking when pregnant Combined causes of variety • E.g. Height, weight Investigating variety: scientists study twins adopted by different families compared to identical twins brought up together and non-identical twins Plant cloning Cuttings Tissue culture • • • • • • • Remove a small section of the plant New roots and shoot will form to give you a new plant Rooting powders and moisture will help the process Quick and cheap Genetically identical plants Used commercially for orchids and fruit trees • • • Expensive but allows thousands of new pants from tiny piece of plant Use plant hormones to make a small group of cells produce a big mass of identical plant cells Using hormones these can then forma new plant This guarantees all plants will have the desired characteristics Animal cloning Embryo cloning • Best cow given fertility hormones to produce lots of eggs and fertilise from best bull • Divide each embryo into individual cells - Each cell grows into an identical embryo in the lab • Transfer embryos into surrogate mothers - Identical cloned calves born Advantages: high quality embryos taken to poor places and produce lots of milk / meat. Can make lots of identical copies of genetically modified embryos that produce genetically useful compounds Adult cell cloning • • Advantages: Save animals from extinction, Bring back prized animals, Clone genetically engineered, medically useful animals (e.g. Those with useful proteins in their milk) Disadvantages: Could lead to cloning humans – ethics? Abuse of science – cloning for organs, Reduces variety – species less able to adapt if there is a change (usually some of the species will survive and reproduce but not if we are all clones) Genetic engineering • Changing the genetic material of an organism • A gene is taken from one organism and transferred into the genetic material of a different organism Genetic engineering – insulin Human engineering: Genetic diseases can be very serious It might become possible to insert ‘healthy’ genes into the affected cells using genetic engineering Exam questions [6 marks] Theories of Evolution Classification and evolution B1.7 Evolution Accepting Darwin’s ideas Natural Selection Theories of Evolution All species of living things alive today have evolved from the first simple life forms Jean-Baptiste Lamarck was a French biologist His idea was that every animal evolved from primitive worms - The change was caused by the inheritance of acquired characteristics Problems: No evidence - People didn’t like to think they descended from worms People could see clearly that changes were not passed onto their children (e.g. Big muscles) Accepting Darwin’s Ideas Darwin travelled the Galapagos Islands and noticed animals were adapted to their surroundings – his theory is that all living organisms have evolved from simpler life forms. This process has come about by natural selection Building up the evidence: • Animal and plant specimens • Breeding experiments with pigeons • Studied barnacles • Network of friends also interested (scientists, pigeon breeders) Why did people object? Religious – god made the world Not enough evidence No way to explain inheritance – genetics not known about Natural Selection 1. 2. 3. 4. Variation Competition Survival of the fittest Reproduction Darwin’s finches Examples of evolution: Peppered moth, Antibiotic resistance in bacteria, Warfarin resistance in rats Mutations: New forms of genes resulting from changes to existing genes – random – mistakes made when DNA is copied in cell division. Mutations introduce more variety. May have no effect or harmful but if better suited to the environment and more likely to survive and reproduce Classification and Evolution Species: A group of similar organisms that are capable of interbreeding to produce fertile offspring Evolutionary tree DNA evidence used to decide which species an animal belongs to and work out evolutionary relationships Exam questions: