Topic 3- Problems of and solutions to a changing environment Flashcards
To revise the keywords from B1 Topic 3.
Drug
A chemical substance that affects the central nervous system, causing changes in psychological behaviour and possible addiction, despite their usefulness.
Painkillers
Painkillers that block pain nerve impulses, including morphine. If the nerve impulses to the brain are blocked, we do not experience a pain sensation and morphine molecules are very effective at doing this.
Hallucinogens
Hallucinogens that distort sense perception, including LSD. When taken, hallucinogens create hallucinations in your mind so you experience distorted sounds and images because the normal processing of nerve impulse is interfered with.
Stimulants
Stimulants that increase the speed of reactions and neurotransmission at the synapse, including caffeine.
Stimulants increase the activity of the brain by increasing the amount of neurotransmitters at certain neurone synapses in the central nervous system i.e. they speed up your brain functions. Stimulants increase your speed of reaction i.e. decrease your response time to a given physical or mental stimulus.
Depressants
Depressants that slow down the activity of the brain (opposite of stimulants), including alcohol.
Depressants slow down your responses and increasing your reaction times to a physical or mental situation i.e. they slow down your brain functions.
Nicotine
Nicotine as an addictive drug which smokers can become dependent on and the more you smoke, the more you may become dependent on it - like it or not, smoking can become a drug addiction.
Tar
Tar is a carcinogen - several molecules (known collectively as carcinogens) in tobacco tar can cause mutations in the cells of the throat and lungs.
Such mutations can eventually lead to throat cancer, and, in particular, lung cancer - whose incidence correlates very highly with smokers.
Carbon monoxide
Carbon monoxide reducing the oxygen-carrying ability of the blood - carbon monoxide combines more strongly with haemoglobin than does oxygen and is slower to be exhaled in the gaseous exchange in the lungs.
Consequently, smokers will have less oxygen in their circulatory system.
Blurred vision
At high intoxication levels you don’t see things clearly as normal and your sense of balance is affected - difficulty walking, impaired memory, slurred speech, in fact most mental and physical activity is interfered with.
Lowering of inhibitions
Antisocial behaviour, from amusing to offensive actions you wouldn’t normally do!
Liver cirrhosis
High ‘doses’ of alcohol can cause the death of liver cells and scarring the liver tissue, eventually restricting the blood flow to the liver. This inhibits the liver from doing its normal cleaning-filtering job of processing waste products from the body like urea. A build up of waste products like urea may harm the rest of your body.
Brain damage
Alcohol abuse is associated with widespread and significant brain lesions - permanent brain damage with potentially fatal consequences.
Infectious disease
An infectious disease is one that spreads from one person to another.
Pathogens
Microorganisms that cause infectious disease are called pathogens.
Bacteria
Very small cells which can rapidly reproduce by cell division in your body making you feel ill by damaging your body’s cells and producing toxins (poisons produced as a by-product of the bacteria’s cell chemistry).
Virus
Viruses are NOT cells and much smaller than bacteria and damage the cells in which they reproduce. Viruses replicate by invading a cell and using the cell’s genetic machinery to reproduce themselves i.e. copies of the original virus. The virus ‘invaded’ cell then bursts releasing lots of new viruses.
Fungi
Fungi are also pathogens and includes microorganisms like yeasts and moulds.
Physical barriers
Physical protection from pathogens. Your skin and hairs and mucous in the respiratory tract can stop a lot of the pathogen cells from entering your body. The whole of the respiratory tract from the nasal passage, down the trachea and into the lungs is covered with mucous and lined cilia (fine hairs that can move freely at their ends). The mucous traps dust and bacteria before they can get down into the lungs and the cilia move the mucous along from the lungs up to the nasal passage -and then you can blow your nose! Skin in good condition acts as a very effective barrier against pathogens. When a cut in the skin occurs, small sections of cells called platelets help the blood to clot quickly to seal the wound (seal = scab when dry) and prevent microorganisms entering the skin tissue or blood stream. The greater the concentration of platelets in the blood the faster the clotting process (‘sealing’) can occur.
Chemical barriers
Hydrochloric acid in the stomach, lysozymes in tears
Chemical protection by killing pathogens. In tears our eyes produce chemicals called lysozymes that kill bacterial microorganisms on the surface of the eye.
Your stomach contains quite concentrated hydrochloric acid which kills the majority of pathogenic bacteria - sadly not all of them at times!
Antiseptic
Antiseptics are chemicals that are applied to the outside of your body to kill pathogens like bacteria or prevent their growth.
Antibiotic
Antibiotics are taken internally e.g. intravenous syringe injection, or orally taken tablet or liquid suspension.
In other words they are treating you from the inside and treat an existing pathogen infection you have (bacterial or fungal microorganism).
Antibacterial
Antibacterials to treat bacterial infections. Probably the most well known antibacterial is the antibiotic penicillin which is effective against many bacterial infections BUT NOT viruses like the common cold or flue. An antibiotic can kill bacteria or prevent them growing and reproducing.
Antifungal
Antifungals to treat fungal infections. Antifungal chemicals kill or prevent the growth of fungi microorganisms e.g creams for the treatment of the fungal infection athlete’s foot.
Photosynthesis
Photosynthesis uses sunlight energy to convert water and carbon dioxide into sugars like glucose, the ‘waste product’ being oxygen - though plants need oxygen for their respiration at night! The simple equation to illustrate photosynthesis is:
water + carbon dioxide (+ sunlight) ==> glucose + oxygen
This energy is stored in the substances that make up the cells of the plants.
Producers
Green plants at the start of a food chain.
Biomass
The mass of living material (the biomass) at each stage in a food chain is less than it was at the previous stage.
Food chain
producer ==> primary consumer ==> secondary consumer ==> tertiary consumer etc.
Respiration
Respiration is the opposite of photosynthesis:
glucose + oxygen ==> water + carbon dioxide (+ energy)
This energy is needed for all life processes, energy to do things like movement of any organism, heat to keep mammals warm.
Parasitism
Where one organism, to survive, feeds off another that acts as the host - parasites ‘take with no give’, live in or on the host which they may harm in the process!
Mutualism
Where two organisms mutually benefit from a relationship- ‘give and take’.
Eutrophication
Eutrophication is a rather deadly situation for aquatic ecosystems in lakes and rivers. Fertilisers have improved agricultural crop yields enormously over the past hundred years, but overuse of nitrogen based artificial fertilisers (e.g. NPK varieties) has caused some major pollution problems. Rainwater will dissolve some of the fertilisers salts (e.g. nitrates and phosphates) and the resulting run-off will concentrate in streams, rivers and lakes. This increases the nutrient concentrations well above the normal background levels associated with a stable ecosystem. The richer source of nutrients, like nitrates, causes a rapid growth in algae, but, so much algae forms, that plants beneath the surface are starved of light and begin to die. The dead plant material is fed on by microorganisms and in doing so, use up the oxygen in the water. The lack of oxygen then begins to kill fish and other animals, which effectively suffocate due to the lack of oxygen for respiration. Sections of streams, rivers and lakes can be devoid of most organisms except the algae!
Polluted water indicator
Bloodworm and sludgeworm.
Clean water indicator
Stonefly and freshwater shrimps.
Air quality indicator
Lichen species and blackspot fungus on roses.
Decomposers
Decomposers release carbon dioxide into the atmosphere. Microorganisms like bacteria and fungi in the soil feed off decaying plant material and animal droppings or remains. Most dead plant matter consists of cellulose which most animals can’t digest, but bacteria and fungi, do have the enzymes to break it down and without their help there would be no carbon cycle. Most of these bacteria and fungi respire aerobically so they need a good supply of oxygen to produce the carbon dioxide essential to keeping the carbon cycle going.
Combustion of fossil fuels
Combustion of fossil fuels releases carbon dioxide into the atmosphere.
Nitrogen-fixing bacteria (Higher)
Nitrogen-fixing bacteria living in root nodules of plants or in the soil can fix nitrogen gas.
Nitrifying bacteria (Higher)
Nitrifying bacteria convert this ammonia to nitrates - the process of nitrification. Nitrifying bacteria oxidise ammonia/ammonium ions from the decayed material to form nitrates, the nitrate ion can be absorbed by plants through their root systems.
Nitrates
Nitrates are needed by plants to make proteins for growth. Nitrates are an essential nutrient for plants to synthesis amino acids and hence proteins.
Denitrifying bacteria
Denitrifying bacteria convert nitrates to nitrogen gas.
Particular bacterial organisms can remove the oxygen from nitrate compounds to form the element nitrogen gas.
These denitrifying bacteria live in anaerobic conditions like waterlogged soils and use the nitrate ion to respire.
This is the opposite function of the nitrogen-fixing bacteria.
