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Natural selection Drugs and clinical trials Control and coordination B1 topics Diet and health Adaptation Cloning and genetic engineering Immunity Competition for resources Energy in food chains 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 electrical impulses along neurones Stimulus Change in the environment Receptor E.g. Eyes, skins, found in sense organs Sensory neurone CNS Brain and spinal cordcoordinates response Motor neurone Effector Muscles (contract) or glands (secrete) Reflex actions- Fast, automatic, protective Synapses Gap between 2 neurones Electrical impulse changed into a chemical messenger Chemical diffuses across the gap to the next neurone Hormones and fertility Produced by Target Effect •Hormone Glands secrete hormones whichorgan are then carried around in the blood Menstrual cycle FSH Pituitary Ovary- developing Stimulates the egg to Contraception Brought about by hormones made and released gland follicle develop Inhibits production by pituitary gland and ovaries of FSH so eggs Hormones: don't mature in the FSH Oestrogen Ovary 1) Uterus 1) Increase the uterus ovaries -causes eggs to mature lining -Stimulates the ovary to produce oestrogen 2) Pituitary gland 2) Stop FSH production Fertility treatments Oestrogen LH Pituitary egg Ovulationeggeggs released FSH used to stimulate to mature -Causes the lining of the uterus toOvarydevelop gland fromoestrogen ovary production and trigger -Inhibits FSH production IVF - eggs collected and fertilised in the -Stimulates the release of the mature egg lab then implanted Others: progesterone and LH Progesterone Ovary1) Uterus 1) Maintain the uterus 28 days: womb liningyellow thickens, Eggs body lining Advantages fewer children released from ovary after 14 days (empty egg - 2) Pituitary gland 2) Stop -FSH production (cost), women freedom ovulation, If not fertilised, the womb follicle) lining and egg come out as a period Disadvantages - expensive, multiple births, embryo use Hormones and fertility • Hormones • Chemical messengers • Produced in glands • Travel in glands • Act on target organs or cells Hormones and fertility Produced by Target Effect •Hormone Glands secrete hormones whichorgan are then carried around in the blood Menstrual cycle FSH Pituitary Ovary- developing Stimulates the egg to Contraception Brought about by hormones made and released gland follicle develop Inhibits production by pituitary gland and ovaries of FSH so eggs Hormones: don't mature in the FSH Oestrogen Ovary 1) Uterus 1) Increase the uterus ovaries -causes eggs to mature lining -Stimulates the ovary to produce oestrogen 2) Pituitary gland 2) Stop FSH production Fertility treatments Oestrogen LH Pituitary egg Ovulationeggeggs released FSH used to stimulate to mature -Causes the lining of the uterus toOvarydevelop gland fromoestrogen ovary production and trigger -Inhibits FSH production IVF - eggs collected and fertilised in the -Stimulates the release of the mature egg lab then implanted Others: progesterone and LH Progesterone Ovary1) Uterus 1) Maintain the uterus 28 days: womb liningyellow thickens, Eggs body lining Advantages fewer children released from ovary after 14 days (empty egg - 2) Pituitary gland 2) Stop -FSH production (cost), women freedom ovulation, If not fertilised, the womb follicle) lining and egg come out as a period Disadvantages - expensive, multiple births, embryo use Hormones and plant growth • Plants are sensitive, they need to grow the right way.. • Phototropism- Plant roots grow away from light and in the direction of gravity • Geotropism- Plant shoots grow towards light and against the force of gravity Controlled by the plant hormone Auxin The opposite occurs in the roots Hormones and plant growth Auxin – hormone that controls the growth of roots and shoot tips 1) Auxin moves to the shaded side of the shoot tip 2) Auxin is unevenly distributed 3) This causes growth on the shaded side 4) Plant bends towards the light 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 New drugs are tested on cells, animal testing (e.g. Mice, rats) and human trials Placebo – pill that does not contain the drug e.g. sugar pill Double blind trial – neither doctor or patient knows who has the real drug Medicines • Thalidomide– – – – Developed as a sleeping drug Found to also cure morning sickness Found to cause limb abnormalities Now used to treat leprosy • Statins– Used to lower blood cholesterol • Painkillers– Only used to treat pain DO NOT KILL PATHOGENS • Antibiotics– Medicines to kill bacteria DO NOT KILL VIRUSES 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 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 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. REMEMBER S->E->A STATE- Camels humps contain a fat store EXPLAIN- Insulates the camel ADVANTAGE- To keep warm during the cold nights 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. 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 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 (water) Environmental change • Organisms can indicate climate change • Lichens are sensitive to Sulfur dioxide • Rat tailed maggots are found in polluted water 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 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 Adult cell cloning 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) Darwin’s Ideas • Variation • Mutation • Adaptation leads to survival • Pass on genes Darwin’s Ideas • Variation- In any species there is variation • Mutation- Caused by mutations in DNA • Adaptation leads to survival- Those with better adaptations will survive • Pass on genespassing on their genes to the next generation Accepting Darwin’s Ideas Why did people object? Religious – god made the world Not enough evidence No way to explain inheritance – genetics not known about 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: