AQA GCSE B1 notes

Diet and Exercise Proteins: Found in meat Build new tissue Growing, repairing cells Made up of amino acids Carbohydrates: Found in foods such as rice, pasta, potatoes, bread Provides energy that releases slowly Fats: Found in foods such as butter, lard and oils Fats provide stored energy Water:Needed for all chemical reactions in your bodyFibre: Found in vegetables and fruit Not a nutrient Helps the digestive system Helps prevent constipation (Can't excrete) Vitamins and Minerals: Required for general health Lack of leads to deficiency diseases --Malnutrition: Can lead to obesity Can lead to being underweight --If energy is not used, it is stored as fat and can lead to obesity.If the body doesn't have enough energy to function, the body loses weight.--Metabolism: The total chemical reactions that are happening in your body Affected by the amount of exercise you do Affected by genetics Affected by the amount of muscle to fat ratio in your body A higher muscle to fat ratio means a higher metabolism Females, generally, have a lower metabolism because they usually have a lower muscle to fat ratio. Affected by biological sex --Cholesterol: A type of fat required to build cell membranes Too much of it can lead to blocked arteries, restricting the amount of blood flowing Can lead to a heart attack Type II Diabetes: Linked to being overweight Body cannot control blood sugar Insulin not working with the cells

Infectious Disease 1Micro-organisms: Bacteria Viruses Fungi Not all are harmful, but those which are are called pathogens --Bacteria: Produce toxins (Poisons) Damages cells Viruses: Much, much smaller than bacteria Invade a body cell and use the cell's functions to reproduce more of themselves Cell bursts and all the viruses escape --Body's defenses:White blood cells ingest pathogens, produce antibodies or produce antitoxinsIngesting pathogens: White Blood cell surrounds a bacterium and engulfs it White Blood cell then digests the bacterium by releasing enzymes Antibodies: Antibodies produced to 'match' with a pathogen's antigen in order to kill it White Blood cell sometimes take a while to find the right antibody to produce Antitoxins:Antitoxins make a bacterium's toxins harmless--Vaccination: Contains an inactive/harmless/dead form of a usually very harmful pathogen White Blood cells are then able to recognise the shape of the pathogen's antigens and produce matching antibodies In the future, matching antibodies are then able to be produced very quickly if the body comes in contact with a more dangerous form of the disease. The more of a population that is vaccinated, the harder it is for a disease to spread. MMR Vaccine: Against measles, mumps and rubella Some scientists think it's linked to autism

Infectious Disease 2MMR Vaccine: Some people believe it caused cases of autism (A condition that affects people's communication and social interaction) Most data shows there is no correlation between use of the MMR vaccine and the cases of autism over time --Ignaz Semmelweis (1850s): Noticed that any time a midwife helped a pregnant woman deliver a baby there was a low number of cases of childbed fever and that when a medical student helped a pregnant woman deliver a baby there was a high number of cases of childbed fever Concluded that high cases of childbed fever were linked to the lack of hygiene (Medical students used to go from working on dead people to delivering babies without washing their hands) Helped with the later discovery of bacteria

Infectious Disease 3Medicines and Antibiotics: Painkillers relieve the symptoms of disease (E.g. headaches) Antibiotics destroy pathogens If antibiotics are prescribed too much, some bacteria develop antibiotic resistance (Developed by mutation (A random, spontaneous change in the DNA)) Antibiotic resistant bacteria then reproduce and are all immune to some antibiotics A bacterium has developed resistance to an antibiotic Bacterium can divide/reproduce Population of antibiotic resistant bacteria is made Scientists develop a new antibiotic to combat this new population Too many antibiotics prescribed = More antibiotic resistance because of mutation in a bacteria's DNA New antibiotic resistant bacteria are produced by natural selection

Infectious Disease 4 - Investigating Cultures of Micro-organismsKeywords: Culturing: Growing a culture of bacteria Petri-dish Inoculating loop Agar jelly/Agar/Nutrient agar/Culturing medium --Growing microbes: Sterilise agar and petri-dish to prevent contamination Inoculating loop is placed in the flame of a bunsen burner to sterilise it and it is then placed into the sample of Microbe X and transferred to the agar using streaking. Petri-dish lid is placed on the petri-dish and is then sealed with tape Petri-dish is incubated at 25°C (In school labs) or 37°C (In science labs) (So that dangerous pathogens aren't produced) Technique is called aseptic technique Disinfectant: Filter paper is soaked in different disinfectants placed in agar jelly with bacteria to find out which is most efficient at killing bacteria Most effective disinfectant will have a larger clear area around it because it killed the most bacteria

The Nervous SystemThe nervous system's job is to detect stimuli and coordinate behaviour appropriately.A stimuli is a change in the environment, e.g. a change in light, temperature, sound, etc.Receptors: Eyes are light receptors Tongue is a chemical receptor Nose is a chemical receptor Skin is sensitive to touch, pressure, temperature and pain Ear is a sound receptor and position receptor Light receptor (Eyes): Retina is a layer of cells at the back of the eye Retina contains light-sensitive cells - rods and cones --Central Nervous System (CNS): Brain and spinal cord Receptors send impulse message to the CNS via sensory neurone CNS uses a relay neurone to then sends an impulse message to an effector via a motor neurone Effectors are muscles (Moves) or glands (Produces hormones) Synapses: A joining of one neurone to another, a gap in between them A chemical message crosses from one neurone to another Reflexes: Responses designed to protect you Doesn't involve the brain because that would take too long Part of the CNS process

Control in HumansHomeostasis: Controlling conditions and substances in the body so some things are not too high and not too low, such as blood sugar or temperature.--Water homeostasis: All chemical reactions in the body happen in a watery environment Water enters the body through drinking or eating certain foods which contain water The body gets rid of water through breathing (Which emits water vapour), sweating and urinating (Via the kidneys) Mineral ions homeostasis: Used for hardening teeth and bones, muscles functioning and improving nerve functionality Gained through eating food Lost through sweating and urination Blood sugar homeostasis: Gained through food and drink Lost through exercise and producing insulin that is a hormone helps to reduce blood sugar Temperature homeostasis: Body must be kept at 37 degrees celcius so enzymes can function effectively, if the temperature is too high or low enzymes become denatured. Gained through exercise or warm conditions Lost through sweating and dilating arteries

Hormones and the Menstrual CycleHormones can control blood sugar (Insulin), control water levels, control the release of eggs in females, control growth, etc.FSH: Produced in the pituitary gland; Function is the mature an egg; Stimulates oestrogen.Oestrogen: Produced in the ovaries; Function is to thicken the lining of the womb/uterus; Inhibits FSH; Stimulates LH.LH: Produced in the pituitary gland; Function is to to release an egg.--Menstrual Cycle: Days 1 to 5: Old egg removed (Period) Days 1 to 12: New egg maturing (FSH) Days 12-16: Egg released (LH) Days 15-23: Egg travels, lining thickens (Oestrogen) Days 20-28: Egg in womb

Hormones in Controlling FertilityStopping pregnancy: Oral contraceptive, e.g. the pill.Encouraging/causing pregnancy: IVF (In vitro fertilisation)First oral contraceptives available had high levels of oestrogen which would inhibit FSH, but side affects included headaches and high blood pressure.Eventually, a progesterone and oestrogen pill was produced and a progesterone only pill. These had much less side effects, if any. Progesterone thickens the lining of mucus in the womb, which means high levels of it will not allow sperm to get into the womb.IVF: In-vitro fertilisation First stage is to give a fertility drug which will contain FSH and LH, which causes the release of mature eggs. Mature eggs are removed and placed in a small petri-dish. Father's sperm is then used to fertilise the eggs Eggs grow into embryos (Small ball of cells) Fertilised eggs are placed into the womb of the mother

Control in Plants/Hormones in PlantsPlants response to stimuli: Phototropism: Plants growing towards light (Negative) Geotropism/Gravitotropism: Shoots growing against the force of gravity (Positive) Geotropism/Gravitotropism: Root growing towards the force of gravity A plant's response to stimuli is done by hormones.Auxin encourages growth in shoots and inhibits growth in roots.Phototropism: When auxin flows downwards evenly, the shoot grows straight When there is light coming from one direction, auxin moves away from the direction of the light, making that side away from the light grows quicker This causes the plant to grow towards the light Auxin in roots: Auxin slows down growth in roots Auxin accumulates on the lower side of a root, meaning that part is growing slower. This means the root grows downwards towards the force of gravity. Use of hormones: Rooting compounds contain hormones Auxins can be used to encourage the rapid growth of weeds, which kills them

AdaptationsPlants compete for light, water, space and nutrients in order to survive and reproduce.Animals compete for food, territory and mates in order to survive and reproduce.Organisms can avoid competition by living in extreme conditions, such as salty conditions (Bacteria, trees (Mangroves)), hot conditions (Camels, bacteria, cacti, desert foxes), and pressured conditions (Bacteria, fish, sea mammals (Whales), dolphins). Adaptations in cold environments: Thick fur (Traps air) Small ears Thick layer of blubber in undersea animals Camouflage Minimised surface area compared to mass Adaptations in warm environments: Large surface area (E.g. large ears) Large supply of blood vessels on ears, increasing heat loss Cacti: Thick stem can store water Spikes are leaves - low surface area, less water loss. Large extensive root system to gather as much water as possible

Environmental ChangeNon-living and living factors have an affect on the population of living things in a particular area.Non-living factors: Temperature Amount of nutrients Rainfall Pollution Living factors: Competition Predators Disease You might be asked to analyse data involving the increase/decrease of a living thing's population depending on environmental change, e.g. global warming.Pollution indicators: Lichens (Air pollution) Invertebrates (Water pollution) Lichen: Sensitive to sulphur dioxide High levels of sulphur dioxide, low level of lichen You might be asked to analyse data involving the increase of pollution and corresponding decrease in pollution indicating lifeforms, in either a graph or table form.Invertebrates: When there is little pollution and high oxygen levels in water, lifeforms such as fresh water shrimp and flat worm thrive. When there is high pollution levels and low oxygen levels in water, lifeforms such as blood worms and rat-tailed maggots thrive

Energy and BiomassThe process of photosynthesis involves converting light energy from the sun into chemical energy in the form of a substance called glucose. Glucose can then be used to produce, proteins, fats and other carbohydrates - all these are used to then create new living tissue, known as biomass.A pyramid of biomass can be made by stacking the biomass of each level of the food chain.Not all the biomass eaten is used to create new tissue. Some biomass is also wasted as waste such as faeces and urine.You may be asked to construct an accurate pyramid of biomass using data given in a table.

DecayPlants require nutrients (Nitrates, mineral ions, etc.) from the soil for healthy growth.Animals also require nutrients for healthy growth, they usually get this through eating plants or other animals.The process in which nutrients from organic waste or dead bodies are returned to the environment is known as decay.Decay is the result of microorganisms eating the waste/bodies, they can break down the nutrients and release them back into the soil.Decay used by people: Compost can be made and put on to soil to encourage growth Dead plant material and waste food is put into a container to encourage enough decay as possible Right conditions is to have plenty of oxygen, a warm temperature and to have moisture in order to organic waste to decay. Holes in a box allow oxygen to enter (Which microbes use for respiration) Respiration produces heat Moisture is gained from rainwater

The Carbon CycleCarbon is used by lifeforms for three main things: Proteins, fats and carbohydrates. These all contribute to create the living tissue of plants and animals.Carbon dioxide in the atmosphere/water can be absorbed by plants either on land or in the sea through photosynthesis.Animals can then eat plants to absorb the carbon. Respiration then also contributes to the carbon dioxide in the atmosphere. The waste animals produce will decay (By microoorganisms, who also respire and contribute to CO2 in the atmosphere). Dead corpses will also decay, the microorganisms also respire and contribute, once again, CO2 to the atmosphere.Fossil fuels come from the remains of plants and animals. We can burn fossil fuels which also produces CO2, adding to the atmosphere. This creates an imbalance of CO2 in the atmosphere since it is no longer removed by lifeforms since fossil fuels take millions of years to happen.

Genetic VariationCharacteristics are the features of a living thing, such as nose shape, hair type, skin colour, petal type, etc.Characteristics are inherited. In both plants and animals, characteristics are passed on to their offspring with genes.Genes are found in the nucleus of every cell in the chromosomes. Chromosomes are made of DNA (Deoxyribonucleic acid). If you were to take on of the chromosomes out, you'd find that along its structure are genes. Genes produce molecules in the body which then go on to show characteristics.Genetic features: Eye colour Ear shape Dimples Tongue rolling Environmental features: Accent Intelligence Personality Religion Skills Both: Weight Height Hair colour Metabolism

Sexual vs Asexual ReproductionSexual reproduction requires male and female sex cells (Gametes). The fusion of gametes leads to creating offspring. Both sperm and eggs carry genetic information, meaning that new offspring are created with the combination of features from the mother and father (Variation).Asexual reproduction only has one parent - no gametes involved. No mixing of genes, no mixing of genetic information. All new offspring are clones (Barring mutation).Some plants grow a runner which grows from the main parent plant, a new plant will grow at the end of the runner eventually. The plant produced is a clone of the parent.Cuttings from plants can be taken, dipped in rooting powder and then grown into an identical clone as the original plant.

Modern Cloning TechniquesTissue culture: Cells are taken from the leaf, stem or root. The cells are then encouraged to grown in nutrient agar jelly which contains vitamins, sugars and hormones (Aseptic technique, must be done in sterile conditions). The cells then grow into plants which are all clones or the original plant. Expensive. Embryo transplants: An egg cell and a sperm cell are fused together to produce a fertilised egg cell (A ball of unspecialised stem cells) The embryo is then split into smaller balls of cells which grow independently. The embryos are then implanted into surrogate mother sheep which give birth to clones of the original embryo. Adult cell cloning: Sheep A has all the perfect characteristics. One of Sheep B's egg cells' nucleus is removed, leaving an egg cell shell. A skin cell is then taken from Sheep A, the nucleus is extracted and then fused into the empty egg cell using an electric shock to create a fertilised embryo. The fertilised embryo is implanted into a surrogate mother sheep where it grows into a foetus.

Genetic EngineeringGenetic Engineering is the transfer of genes from one living thing to another living thing.Process: Scientists find the gene responsible for the desired characteristic - E.g. producing a needed hormone (I.e. insulin) Scientists then remove the gene from a chromosome using a specific enzyme. The extracted gene can then be implemented into the chromosome of another living thing - e.g. a bacterium. The other living thing then reproduces and creates more of the modified living thing. GM crops are very controversial: Fears that they'll affect an ecosystem, damage humans or animals or have worse consequences far into the future. Many people are against GM crops.

EvolutionEvolution was first proposed by Charles Darwin. His theory was that different species of living things nowadays developed over millions of years from common, basic ancestors.When Darwin first published his idea, many people didn't agree with him. People believed that God created everything, there wasn't enough evidence to convince people and there was no way of understanding how variation occurred at that time.Evolution: Evolution occurs by natural selection. All living species show variation. Some features give an advantage. Creatures with this beneficial feature would live longer, breed more and therefore pass on their genes. The species then changes over time with the most beneficial features needed for survival. Different species can branch off from a common ancestor because some may live in a different environment and need different adaptations. Characteristics can happen from a result of mutation (A random and spontaneous change in the genes of a lifeform). Sometimes mutations can give an advantage.

Darwin and LamarckJohn Baptiste Lamarck lived around the time of Darwin and proposed a theory of evolution shortly before Darwin.Lamarck believed that organisms that use a feature more (Such as a trunk or long neck) will 'stretch' them and therefore pass them on to their offspring.Lamarck said that individuals in a species can change their features over their lifetime. These changes, made by the living thing itself, can be passed on to offspring.

Medical DrugsDrugs are substances that affect a body's chemistry.Medical drugs: Drugs you take when you're ill to make you feel better.Recreational drugs: Categorised into legal and illegal drugs. Legal drugs include nicotine, alcohol, tobacco. Illegal drugs include cocaine, cannabis, heroin. Performance enhancing: Associated with athletes that make them stronger and faster.--All new drugs must be first tested to make sure they're safe. This stage is called toxicity testing. It involves testing the drug on cells, tissues and animals in the lab.Clinical trials are then done with young and healthy volunteers. They are given small doses of the drug to then find out how it affects them.Further clinical trials are then done. An example of one form of further clinical trialling is a double blind trial which involves volunteers with the illness targeting and the doctor, both of which are blind to whoever gets placebo drugs (False versions of the drug to find out whether the affect is real of psychological) and real drugs. The doctor is also blind so that they are not biased in their recordings.If the drug passes all of these tests it is then approved.--Thalidomide: A drug that was initially developed to help people sleep. Went through appropriate testing as a sleeping pill and was approved. It was found it can also treat morning sickness for pregnant women. The drug wasn't tested on pregnant women, meaning that the pregnant women who took thalidomide to relieve morning sickness later ended up having deformed children affected by the drug. The drug was then banned after the side affects on pregnant women were discovered, but it was too late as many children were still born with deformed limbs. Since it was banned, the drug has been found to be useful in treating leprosy and a few other diseases.

Drugs in Recreation and SportWhy do people take recreational drugs? Improve mood/feel happier (Euphoria) More relaxed To socialise Nicotine and alcohol are addictive - The body becomes dependent on them and not having them leads to withdrawal symptoms.Cocaine and heroin are highly addictive, the withdrawal symptoms are very severe. Heroin, cannabis and ecstasy can also affect the heart and circulatory system.There is evidence to suggest that cannabis can lead to mental illness, it is also viewed as a 'gateway' drug into other, harder drugs.Overall, nicotine and alcohol have a bigger affect on society than cocaine, heroin, cannabis and ecstasy because many more people take the legal drugs.--Performance enhancing drugs include anabolic steroids, stimulants and others. Anabolic steroids build muscle and are popularly used by athletes, they are mostly banned by sport organisations, though. Stimulants can increase heart rate, improve stamina and improve general performance. Beta blockers help people to stay calm and steady, used in sport such as archery and snooker.Many people are against using drugs in sport because using artificial methods is unfair. All major competitions ban performance enhancing drugs.