21/04/23Topic 3 – Problems of and solutions to a changing

environment

21/04/23

Introduction to DrugsDrugs are classed as “a substance that affects the central nervous system, causing changes in psychological behaviour and possibly addiction”. Some examples:

Type of drug Effects Examples

Painkiller Block nervous impulses

Morphine, aspirin

Hallucinogen Distort sense perception

LSD

Stimulant Increase reactions Caffeine

Depressant Slow down brain activity

Alcohol

21/04/23Investigating Reaction Times

Task: Design an experiment that investigates the affect of caffeine on reaction times.

Variables: What are the independent, dependant and control variables?

Results: Draw your own results table:

Conclusion: What do your results show you?

21/04/23

SmokingCigarettes contain 3 harmful things:

1. NICOTINE, which is an ___________ drug that raises the heart beat, narrows the arteries and so causes ____ _____ _____. This leads to heart _________.

2. TAR, which coats the lining of the _______ making them less able to take in oxygen. It also contains carcinogens which cause ______________.

3. CARBON MONOXIDE, which is a _______ ____ which joins up with ____ blood cells making them incapable of transporting _____________ around the body. In pregnant women it can cause oxygen deprivation, leading to low birth ______.

Words – high blood pressure, oxygen, red, addictive, disease, poisonous gas, lungs, cancer, mass

21/04/23

Tobacco and Lung Cancer

Sir Richard Doll, 1912-

2005

Over 50 years I proved the link between smoking and lung cancer. I published my first findings in 1950, based on patients in

London hospitals, and then studied 40,000 doctors and proved a link in a

paper published in 1954.

Smoking has existed in Western culture since the 16th Century. However, scientists only proved the link between it and various diseases shortly after the Second World War.

21/04/23Cancer Research UK statistics

What do these statistics imply?

21/04/23

The spread of infection

Ignaz Semmelweiss

1818-1865

Guten tag. In the mid-19th century I realised that many deaths in hospitals could be avoided by insisting on clean hands and equipment. As a result of my work deaths

in my wards fell from 12% to 1%.

More people die due to infections from hospitals than on the roads in Britain. Hospitals have been trying to improve hygiene standards:

Year Amount of hand wash solution used

(litres per 1000 patient days)

MRSA infections per 100 patients

1993 3.5 0.50

1995 6.9 0.48

1997 10.9 0.25

21/04/23

VaccinationsSome people argue that the MMR vaccine is a good idea, others think it is a bad idea. Briefly summarise each side of the argument:

MMR vaccine

For Against

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TuberculosisTuberculosis is a bacterial disease caused by “mycobacterium tuberculosis”. It usually affects the lungs and the bacteria are spread in coughs and sneezes.

National vaccinatio

n starts

1953

TB bacteria can cause cavities or lumps in the

lungs

No. of cases of TB in Britain

Year

140,000

21/04/23

Researching new medicinesBefore new drugs can be approved they have to go through three stages:

3. Does it work? People with the illness are tested on

1. Is it toxic? Tests are done on animals

2. Is it safe for humans? Human volunteers trial the drug

21/04/23

HIV and AIDS

Graph showing HIV and AIDS trends in the UK.

HIV stands for Human Immunodeficiency Virus, and can be undetected for years before developing into....

AIDS, which stands for Acquired Immune Deficiency Syndrome.

21/04/23

Vaccination Policies

Factors to consider about vaccinations

Is the infection a big risk?

Who is at risk?

Is the vaccine safe?

How much does it cost?

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Developing new drugsBefore a new drug can be approved it has to go through a strict testing process. Consider the example of thalidomide:Date Event

Mid 1950s

Late 1950s

Early 1960s

Mid 1960s

Animal testing using thalidomide was undertaken. Tests showed that it was safe but the tests were “inadequate” – no tests were done on pregnant animals

Thalidomide prescribed to pregnant mothers to help sleep and morning sickness problems

Babies are born with birth defects and the drug was banned worldwide. Around 12,000 deformed Thalidomide babies born, 4,000 die in first year.

Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose.

21/04/23

PlacebosClinical trials can be done in different ways:

1) Blind trials

Patients do not know which drugs they are taking – a real drug or a “placebo”

2) Double blind trial

Neither the doctors or the patients know if they are taking the real drug

Placebos offer anethical dilemma as a patient might be sick and still be given a “dummy” pill. Also, you might notice if you had a placebo as you wouldn’t get the side effects of normal drugs...

21/04/23

Malaria

21/04/23

Drugs Research ProjectExplain and give examples for the following:

1) Why do people use legal drugs?

2) What are the drawbacks of legal drugs?

3) Alchohol is a legal drug. What does it do to the

human body?

4) Why do people use illegal drugs?

5) What are the drawbacks of illegal drugs? What can

they cause?

6) Find out which drugs are in which classes

21/04/2321/04/23

The Effects of AlcoholThe Effects of Alcohol

Time Effects

Short term

Long term

Blurred vision, lowering of inhibitions, slowing of reactions

Liver cirrhosis, brain damage

21/04/23

Organ TransplantsIt is possible to perform transplants of major organs, including:

The lungs

The heart

The liver

I don’t think organ transplants should be

allowed because if people damage their

lungs by smoking then it’s their fault.

What do you think?

21/04/23

PathogensPathogens are microbes (micro organisms) that can cause diseases. They can enter the body in a number of ways:

…or other natural openings…

They can be breathed in through the mouth or nose

They can enter through cuts or bites in the skin

21/04/23

Spreading of PathogensDiseases and pathogens can be spread by a number of means, including:

Cholera bacteria, spread in water

Salmonella bacteria, found in food

Influenza virus, spread through the air

Athlete’s foot, a fungus spread through contact

Malaria, spread through “vectors”, e.g. mosquitoes

HIV, spread through body fluids

21/04/23Microbes: our defence against them

Our bodies have defence mechanisms against invading microbes:

If our skin is cut platelets seal the wound by clotting

The breathing organs have hairs and produce mucus to cover the lining of these organs and trap the microbes

The skin acts as a waterproof barrier

The stomach contains hydrochloric acid, which kills bacteria

Tears contain lysozyme, an enzyme that kills bacteria

21/04/23

Rainforest medicinesMany plants contain chemicals that have natural antibiotics effects in order to defend themselves. Many of these substances can be used by humans.

21/04/23

Using Antibiotics

1) Overuse of antibacterials can lead to bacteria becoming resistant (e.g. the MRSA “superbug”). This means that antibiotics must be used sparingly.

2) Antifungals can be used to treat fungal infections like Athlete’s foot

21/04/2321/04/23

Resistance to antibioticsResistance to antibioticsAlthough vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”:

1) Mutation – some strains of bacteria can develop _______ to the antibiotics.

2) The non-resistant bacteria are _____ by the _______.

3) The resistant bacteria _______ and pass on their mutations to their ______. Don’t use antibiotics unless you need to!!

Bacteria

Penicillin

No effect!!

Words – offspring, resistance, killed, antibiotics, reproduce

21/04/23

The rise of MRSANo. of MRSA cases

Year

21/04/23

Growing micro organismsMethod:

1) Sterilise the inoculating loop

2) Dip the loop in the bacteria and spread it across the agar

3) Secure (but don’t seal) the lid with tape

Questions:

1) Why are you sterilising the loop?

2) What does the agar do?

3) Why is the lid not sealed all the way around?

4) What can you now do to investigate the affect of antibiotics?

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Food chainsFood chainsA food chain shows where the biomass or energy goes in a food chain (in other words, “what gets eaten by what”):

Cabbage

Rabbit Stoat Fox

The arrows indicate where the energy is going

Plants convert the sun’s energy into food

through photosynthesis

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Pyramids of biomassPyramids of biomassIn this food chain we can see that the mass of organisms in each stage is less than in the previous stage:

Cabbage

Rabbit Stoat Fox

We can draw a “Pyramid of Biomass” to show this pattern:

Mass of cabbages

Mass of rabbits

Mass of stoats

Mass of foxes

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Energy flow in a food chainEnergy flow in a food chainConsider the energy flow in this food chain:

Cabbage

Rabbit Stoat Fox

100% 10% 1% 0.1%

Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain.

Energy is lost to the surroundings at each stage because of a number of reasons:

1) Each organism has to ____, keep warm etc

2) Energy is lost through faeces (______)

Words – 10%, move, sun, waste, cabbage

21/04/23Interdependent Relationships

1) Parasitic relationships

2) Mutualistic Relationships

Parasites take food from another living host _______. For example, if a human eats pork infected with bladderworm the worms attach themselves to the ___ wall and a young tapeworm grows, which _______ food from the gut.

Mutualistic relationships are when two organisms benefit from each other. For example, pea plants have nitrogen-fixing ______ which convert nitrogen into nitrates for plant _____. The bacteria benefit by taking sugars from the plant for ___________.

Words – growth, respiration, organism, gut, bacteria, absorbs

21/04/23Interdependent Relationships

Task: Find out about other examples of parasitism and mutualism. Find two further examples of each and explain how each of the organisms depends on the other.

21/04/23

Global Population Changes

10,000BC 8,000BC 6,000BC 4,000BC 2,000BC 0 2000AD

Glo

bal

Popu

lati

on

Q. What do you think the following graph would look like?

21/04/23

Global Population ChangesStatistics from Wikipedia:

The world’s population is currently growing by 1,000,000,000 people every 10-15 years

21/04/23

Population and Pollution

The human population is growing exponentially:

Population

Time

This has a number of effects on the environment:

Bigger population means…

Building – more

buildings needed

Farming –less land

available for crops

Waste –more waste needs to be disposed of

Pollution –More phosphates,

nitrates, CO2 and SO2

21/04/23EutrophicationYet another example of pollution, eutrophication is when lakes become stagnant due to careless use of fertiliser. There are six steps:

1) Inorganic fertilisers used on fields are washed into the lake

3) This growth causes overcrowding and many plants die due to lack of enough light or food

2) The fertiliser causes increased growth in water plants

21/04/23

Eutrophication4) Microorganisms and bacteria increase in number due to the extra dead material

5) These microorganisms use up the oxygen in the lake during respiration

6) The lack of oxygen causes the death of fish and other aquatic animals

Can’t…breathe…

21/04/23

Eutrophication4) Microorganisms and bacteria increase in number due to the extra dead material

5) These microorganisms use up the oxygen in the lake during respiration

6) The lack of oxygen causes the death of fish and other aquatic animals

21/04/2321/04/23

Pollution IndicatorsPollution Indicators

Lichens in very clean air

Lichens in clean air

Lichens in slightly dirty air

Lichens can be used as air pollution indicators:

21/04/2321/04/23

Pollution IndicatorsPollution Indicators

In dirty water leeches and midges will survive

In average water more species (like the dragonfly and cranefly) will survive

In clean water a lot more species (like the mayfly and caddisfly) will survive

The quality of water can be monitored by looking at the species of insect in the water:

21/04/23Reducing Pollution by Recycling

Recycling

Reasons why recycling is good Reasons why recycling is bad

Reduces demand for raw

materials

Reduces the amount of rubbish going to landfill

sites

Paper, metal and plastic can be recycled

Still requires energy

Requires money to sort and

recycle

21/04/2321/04/23

Recycling ourselvesRecycling ourselves

Microbes are the key to this – they break down waste and dead bodies so that the products can be used by plants for growth. Microbes work best in warm, moist conditions where there is plenty of oxygen.

Eating

Waste

Death

Broken

down

Absorption

21/04/2321/04/23The Carbon The Carbon CycleCycle

CO2 in air 1. CO2 is taken

in by plants and algae for photosynthesis and turned into carbohydrates, fats and proteins

2. Plants and algae release CO2 through respiration

3. The carbon taken in by plants is then eaten by animals and the animals that eat them

5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders

6. These microbes also release CO2 through respiration 4. Animals

release CO2 through respiration

Burning fossil fuels also releases CO2

21/04/23

The Nitrogen Cycle1. Nitrogen-fixing bacteria convert N2 in the air into nitrates

2. Plants are then eaten by animals – the nitrogen becomes PROTEIN

3. Decomposers break down waste products and dead animals and plants to form AMMONIUM COMPOUNDS

4. Denitrifying bacteria convert nitrates and ammonium compounds into atmospheric nitrogen

Nitrates in the soil

Waste and dead animals

6. Nitrates taken in by plants

N2 in air

5. Nitrifying bacteria convert ammonium compounds into nitrates

Lightn

ing

Denitrifyin

g

bacte

ria

1. Fe

rtilisers