B1 topics Natural selection Diet and health Immunity Control and co- ordination Competition for resources Adaptation Drugs and clinical trials Energy in food chains Cloning and genetic engineering

B1.2 Coordination and Control Responding to change Reflex actions Hormones and menstrual cycle Fertility Homeostasis Hormones and plant growth

Responding to change The nervous system carries electrical impulses along neurones Stimulus Receptor Sensory neurone CNS Motor neurone Effector Change in the environment E.g. Eyes, skins, found in sense organs Brain and spinal cord- coordinates response 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 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 HormoneProduced byTarget organEffect FSHPituitary gland Ovary- developing follicle Stimulates the egg to develop OestrogenOvary1)Uterus 2)Pituitary gland 1)Increase the uterus lining 2)Stop FSH production LHPituitary gland Ovary- eggOvulation- egg released from ovary ProgesteroneOvary- yellow body (empty egg follicle) 1)Uterus 2)Pituitary gland 1)Maintain the uterus lining 2)Stop FSH production

Hormones and fertility Hormones Chemical messengers Produced in glands Travel in glands Act on target organs or cells

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 HormoneProduced byTarget organEffect FSHPituitary gland Ovary- developing follicle Stimulates the egg to develop OestrogenOvary1)Uterus 2)Pituitary gland 1)Increase the uterus lining 2)Stop FSH production LHPituitary gland Ovary- eggOvulation- egg released from ovary ProgesteroneOvary- yellow body (empty egg follicle) 1)Uterus 2)Pituitary gland 1)Maintain the uterus lining 2)Stop FSH production

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.. 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 The opposite occurs in the roots Controlled by the plant hormone Auxin

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 The opposite occurs in the roots Using plant hormones – used as rooting powder or high doses as weed killers due to rapid uncontrolled growth

Exam Questions

B1.3 Medicine and Drugs Drugs Developing new medicines How effective are medicines Legal and illegal drugs Drugs in sport Cannabis and hard drugs

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

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Adaptation for survival Adapt and survive Adaptation in animals Adaptation in plants Competition in animals and plants Environmental change

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?

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B1.5 Energy in biomass Pyramids of biomass Energy transfers Decay processes Carbon cycle Recycling organic waste

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 3060 KJ in food 1110 KJ in heat loss 1797 KJ in urine and faeces 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)

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 – CO 2, 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

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B1.6 Variation Inheritance Cloning plants Types of reproduction Genetic and environmental differences Genetic engineering 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 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 Asexual reproduction 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 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 Tissue culture 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 cloningAdult cell cloning

Genetic engineering

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B1.7 Evolution Theories of Evolution Accepting Darwin’s ideas Natural Selection Classification and evolution

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 genes- passing 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

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