B1: Topic 3 and 4

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  • B1: Topic 3 and 4
    • Effects of drugs
      • A drug is a chemical that effects the central nervous system. It can change your physical behaviour, which is why you thing or feel. For example, narcotics make you feel sleepy. Some drugs cause addiction. therefore, the person becomes dependant on taking the drug and feels they cannot function properly without it.
        • Smoking releases carbon monoxide which reduces how much oxygen the blood can carry. The nicotine in it is addictive. Chemicals in tar are carcinogens that cause cancers, particularly of mouth and lung.
        • Different tpes of drug: A painkiller blocks nerve impulses from pain receptors so you don't feel as much pain, e.g. morphine. A stimulant increases neurotransmission at synapses, so increase speed of reaction, which reduces reaction time, e.g. caffeine. A depressant slows the activity of the brain, so increases reaction time, e.g. alcohol. A hallucinogen changes perception for example colours seem brighter: can make it difficult to distinguish between real or not real, e.g. LSD.
    • Effects of alchol
      • Short term effects: Blurred vision. Slow reactions. Lowered inhibitions so you take more risks.
      • Long term effects: Brain damage. Liver ciirrhosis.
    • Ethics and Transplants
      • Some diseases can be cured by transplanting a healthy organ from one person to another. there are never enough healthy organs available for all who need transplants, and many paitents will die while waiting for an organ.
      • Ethics is about what you think is right or wrong. Different people have different opinions. For example... Argument 1: if two patients need a heart transplant, a patient who is not obese should have priority as they have a higher chance of survival. Argument 2: everyone should be treated equally because an obese patient may not be able to control their weight.
    • Pathogens and Infection
      • An infectious disease is one that can be passed from one person to another. A pathogen is an organism that causes an infectious disease.
      • Pathogens are spread in different ways. fore example eating food containing pathogens e.g. Salmonella. Breathing in air from coughs and sneezes. Drinking water containing pathogen, e.g. cholera. Exchange in body fluids containing pathogens, by infected needles or during sexual intercourse. Direct contact with infected surfaces,e.g. athlete's foot.
      • Physical barriers against pathogens: Skin. Mucus in breathing passages and lungs trap pathogens. Cilia move mucus and trapped pathogens out of lungs.
        • Chemical Defences against pathogens: Hydrochloric acid in stomach kills pathogens in food and drink. Lysozyme enzymes in tears kills pathogens and prevent them entering the eye.
    • Antiseptics and Antibodies
      • Many plants make chemicals that help to protect them from attack by bacterial pathogens. these chemicals are called antibacterials. We use some of these antibacterials to help protect us from infection.
        • The different treatments are antibiotics which is a chemical taken as a medicine that ills some ids of microorganisms, or stops they growing, after they have infected they body. Antibacterial is a general name for chemical that kills bacteria or sops them growing. Antifungal is a chemical that kills fungi or stops them growing. Antiseptics is a chemical used to prevent infection by killing pathogens on surface before they can get into the body.
      • Antiboitic resistance: Antiboitics kill all but the most resistant bacteric. If these bacteria get intothe environment, thay cancause antibiotic-resistance infections. Those is because if the antibiotics are not used only when essential they wont work. or if someone is given antibiotics but doesn't use them for the whole course subscribed them the pathogens are not all killed therefore the person will feel better but when they stop taking them they will just get worse.
        • Misuse of antibiotics has led to the development of bacteria resistant to many antibiotics, such as MRSA.
    • Interdependence and Food Webs
      • Chemical energy is transferred from one organism to another along a food chain or food web. All living organisms are interdependent due to their feeding relationships. These relationships are always changing, as a change in numbers or organisms I one trophic level will affect other trophic levels.
        • Producer ----> Primary Consumer ----> Secondary Consumer
      • Energy Flow. Light energy taken in during photosynthesis used to make new plant tissue. Chemical energy stored as new plant tissue which can be transferred to herbivores in their food. Heat energy from respiration transferred to surroundings.
      • A pyramid of biomass is a diagram that hsows the amount of biomass at each trophic level of a food chain. The producer level is the bottom bar, and the other bars show the trophic levels in order. The amount of biomass at each trophic level along the food chain gets smaller. Due to the energy at each level is transferred as heat energy to the environment. Food chains are usually 4 trophic levels long as there is not enough biomass in the top level to provide the energy needed by another trophic level.
    • Parasites and Mutualists
      • A parasite feeds on another organism while they are living together. Taking food from the host usually harms it but doesn't kill it. A parasite may be a plant or an animal.
        • Mutualism is when two organisms live closely together in a way that benefits them both.
          • The oxpecker bird benefits by getting food and the herbivore benefits from loss of skin parasites. Cleaner fish benefit by getting food and the larger fish benefits from loss of dead skin and parasites.
      • Fleas feed by sucking on the animals blood after piercing its skin- they feed on other animals including humans. A head louse feeds by sucking blood after piercing the skin on the head- feed on humans. Tapeworms live in the intestines and absorb nutrients from the digested  food in the intestine- they feed off other animals including humans. Mistletoe grows roots into the tree to absorb water and nutrients from the host- they feed off of trees.
    • Pollution
      • The global human population is increasing. This is because each year the number of babies born is larger than the amount of people who die. As human population increase, population will increase unless we find ways to reduce the amount of population we produce.
      • Some human activities cause pollution. A pollutant is a substance that can damage the environment and the organisms that live in in. Pollutants include: sulphur dioxide gas released from factories and power stations. Phosphates and nitrates from sewage and fertiliser, which pollutes water.
        • Eutrophication: Farmers uses too much fertiliser on their crops. When it rains the excess fertiliser runs into the river when it rains. The fertiliser causes the algae to grow quicker. the algae uses all the oxygen up I the water. Therefore, the fish and plants die due to lack of oxygen.
    • Pollution Indicators
      • Some species are well adapted toliving in polluted conditions. Other species can only live where there is no pollution. The presence or absence of these indicator species can show us whether of not there is pollution.
        • Indicators if air pollutions: Some species of lichen can only grow where there is not pollution. Other species can grow where there is air pollution. So the species of lichen growing on trees can tell you if the air is polluted. Blachspot is a fungus that infects roses. The fungus is damaged by sulphur dioxide in the air. So where there is air pollutions, the roses are clear to the fungus.
          • Indicators of water pollution: Blood worms can live in water that contains little oxygen. So they are found in polluted water. Stonefly larvae and freshwater shrimps can only live in water that contains a lot of oxygen. So they are indicators of unpolluted water.
      • Recycling means to re-use materials. Materials that are commonly recycled include metals, paper and plastics.


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