Topic 3- Problems of and solutions to a changing environment

Question 1

Drug

Answer 1

A chemical substance that affects the central nervous system, causing changes in psychological behaviour and possible addiction, despite their usefulness.

Question 2

Painkillers

Answer 2

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.

Question 3

Hallucinogens

Answer 3

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.

Question 4

Stimulants

Answer 4

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.

Question 5

Depressants

Answer 5

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.

Question 6

Nicotine

Answer 6

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.

Question 7

Tar

Answer 7

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.

Question 8

Carbon monoxide

Answer 8

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.

Question 9

Blurred vision

Answer 9

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.

Question 10

Lowering of inhibitions

Answer 10

Antisocial behaviour, from amusing to offensive actions you wouldn’t normally do!

Question 11

Liver cirrhosis

Answer 11

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.

Question 12

Brain damage

Answer 12

Alcohol abuse is associated with widespread and significant brain lesions - permanent brain damage with potentially fatal consequences.

Question 13

Infectious disease

Answer 13

An infectious disease is one that spreads from one person to another.

Question 14

Pathogens

Answer 14

Microorganisms that cause infectious disease are called pathogens.

Question 15

Bacteria

Answer 15

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).

Question 16

Virus

Answer 16

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.

Question 17

Fungi

Answer 17

Fungi are also pathogens and includes microorganisms like yeasts and moulds.

Question 18

Physical barriers

Answer 18

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.

Question 19

Chemical barriers

Answer 19

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!

Question 20

Antiseptic

Answer 20

Antiseptics are chemicals that are applied to the outside of your body to kill pathogens like bacteria or prevent their growth.

Question 21

Antibiotic

Answer 21

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).

Question 22

Antibacterial

Answer 22

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.

Question 23

Antifungal

Answer 23

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.

Question 24

Photosynthesis

Answer 24

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.

Question 25

Producers

Answer 25

Green plants at the start of a food chain.

Question 26

Biomass

Answer 26

The mass of living material (the biomass) at each stage in a food chain is less than it was at the previous stage.

Question 27

Food chain

Answer 27

producer ==> primary consumer ==> secondary consumer ==> tertiary consumer etc.

Question 28

Respiration

Answer 28

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.

Question 29

Parasitism

Answer 29

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!

Question 30

Mutualism

Answer 30

Where two organisms mutually benefit from a relationship- 'give and take'.

Question 31

Eutrophication

Answer 31

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!

Question 32

Polluted water indicator

Answer 32

Bloodworm and sludgeworm.

Question 33

Clean water indicator

Answer 33

Stonefly and freshwater shrimps.

Question 34

Air quality indicator

Answer 34

Lichen species and blackspot fungus on roses.

Question 35

Decomposers

Answer 35

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.

Question 36

Combustion of fossil fuels

Answer 36

Combustion of fossil fuels releases carbon dioxide into the atmosphere.

Question 37

Nitrogen-fixing bacteria (Higher)

Answer 37

Nitrogen-fixing bacteria living in root nodules of plants or in the soil can fix nitrogen gas.

Question 38

Nitrifying bacteria (Higher)

Answer 38

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.

Question 39

Nitrates

Answer 39

Nitrates are needed by plants to make proteins for growth. Nitrates are an essential nutrient for plants to synthesis amino acids and hence proteins.

Question 40

Denitrifying bacteria

Answer 40

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.