03/02/15

Biology Unit 1Biology Unit 1

W Richards

The Weald School

(AQA)

03/02/15Balanced dietBalanced dietA balanced diet should contain fats, proteins and carbohydrates in roughly these amounts:

It should also contain water, vitamins, minerals and fibre.

03/02/15Poor dietsPoor dietsIf we don’t have a balanced diet we may suffer form a “deficiency symptom”. You don’t need to know all of these links but they show what can happen to your body…

Vitamin D

Protein

Vitamin C

Vitamin A

Iron

Calcium

Anaemia

Scurvy (bleeding gums and joints)

Weak bones and teeth

Wasting of body tissue

Rickets

Poor night vision

Lack of… Causes…

03/02/15Metabolic Rate and healthMetabolic Rate and healthThe rate at which our bodies carry out chemical reactions is called the “metabolic rate”. This rate varies with:

• The amount of work we do

• The amount of fat in our body

• Inherited factors

Condition How this affects our health

Lack of exerciseFatty dietsWarm weatherUsing cars instead of walkingPlaying XBox instead of football

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Modern diets and health problemsModern diets and health problems

% obesity in the UK

This happens when the body is taking in more energy then it is “burning”.

03/02/15Heart diseaseHeart disease

Cholesterol

The amount of cholesterol in the body can be lowered using drugs called “statins”.

03/02/15Conditions caused by increased weightConditions caused by increased weight

Obesity is a condition caused by excess weight. This can also lead to the following diseases:

AthiritisWhat is it?

What causes it?

Heart diseaseWhat is it?

What causes it?

High blood pressureWhat is it?

What causes it?

DiabetesWhat is it?

What causes it?

03/02/15MicrobesMicrobesMicrobes are 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

03/02/15DiseaseDiseaseA disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes) or it could be caused by a type of PATHOGEN (a microbe that causes disease):

VirusesBacteria

• 1/1000th mm big

• Living cells (some are harmless)

• Grow very quickly

• Affected by antibiotics

• Examples: food poisoning, tetanus, sore throats

• 1/1,000,000th mm big

• Genetic info inside a protein coat

• Not affected by antibiotics

• Release poisons

• Examples: colds, flu, polio, chicken pox

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Microbes: our defence against themMicrobes: our defence against themOur bodies have four major defence mechanisms against invading microbes:

If our skin is cut platelets seal the wound by clotting

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

The skin acts as a barrier

Our blood contains white blood cells

03/02/15Fighting diseaseFighting diseaseIf microbes enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS:

White blood cells do 3 things:

1) They eat the microbe

2) They produce antibodies to neutralise the microbe

3) The produce antitoxins to neutralise the poisons produced by microbes

03/02/15Producing antibodiesProducing antibodies

Step 1: The white blood cell “sees” the pathogen (microbe)

Step 2: The cell produces antibodies to “fit” the pathogen

Step 3: The antibodies fit onto the pathogens and cause them to “clump”

Step 4: The pathogens are “eaten” by the white blood cells

You’re going down

03/02/15Specific antibodiesSpecific antibodies

Antibodies are specific – they will neutralise the microbe they have been made for.

03/02/15Fighting diseaseFighting diseaseNATURAL IMMUNITY

This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy.

ARTIFICIAL IMMUNITY

Can be done in two ways:

1) A vaccine with dead microbes is injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION

2) The antibodies are injected directly into the body – this is called ACTIVE IMMUNISATION.

03/02/15Using AntibioticsUsing AntibioticsAntibiotics can be used to kill bacteria. However, there are

two problems:

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

2) Antibiotics have no effect on a virus, like the common cold. It is difficult to kill a virus without damaging body tissue. A virus is usually allowed to “run its course”.

03/02/15Resistance 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

03/02/15Using PainkillersUsing PainkillersPainkillers are drugs used to relieve the symptoms of disease but without killing the pathogens, for example:

ParacetamolAspirin

Ibuprofen

03/02/15The spread of infectionThe 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 0.501995 6.9 0.481997 10.9 0.25

03/02/15Growing micro organismsGrowing 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) Why would you not want to culture your bacteria at 37OC?

03/02/15The Nervous SystemThe Nervous SystemThe NERVOUS SYSTEM enables us to react to our surroundings. It consists mainly of the brain, the spinal chord, nerve cells (“neurones”) and receptors.

Types of receptor:

1) Light receptors in the eyes

2) Sound receptors in the ears

3) Taste receptors on the tongue

4) Smell receptors in the nose

5) Touch, pressure and temperature receptors in the skin

6) Changes of position receptors in the ears (balance)

03/02/15Nervous ReactionsNervous ReactionsWhen we react to a stimulus our bodies use the following pattern:

Stimulus Receptor Coordinator Effector Response

For example, consider a man and a camel: Oh

No!

What are the stimulus, receptor, coordinator, effector and response in this situation?

03/02/15Examples of reactionsExamples of reactionsStimulus Receptor

(i.e. the thing that detects the

stimulus)

Effector (i.e. the thing that will do the

reaction)

Response (i.e. action

taken)

Bright light

Sour taste

Losing balance

Sit on a drawing pin

03/02/15Conscious actionsConscious actionsA conscious action is one where the brain makes a considered response. Here’s what happens:

Stimulus Receptor Sensory Neurone Coordinator

Motor Neurone Effector Response

1) Receptors in your skin detect a stimulus

3) Here another sensory neurone carries the signal to the brain

4) The brain decides to move away the hand

5) This impulse is sent by MOTOR NEURONES to the hand muscles (the effectors) via the spinal chord…

2) The impulse is carried by SENSORY NEURONES to the spinal chord

6) Which then moves the hand away

03/02/15Reflex actionsReflex actionsSometimes conscious action is too slow to prevent harm, e.g…

In situations like this the body bypasses the brain to produce a quicker response. Here’s how it works…

03/02/15Reflex actionsReflex actions

1. Receptor

2. Sensory neurone

3. Relay neurone in the spinal chord

4. Motor neurone

5. Effector

03/02/15Types of nerve cellTypes of nerve cellNucleus Muscle strands

(effector)Cell body

1) Motor neurone 2) Sensory neurone 3) Relay neurone

Impulse Impulse

Nerve cells (neurones) are elongated with branched endings to connect to many muscles fibres.

03/02/15SynapsesSynapses

Neurones never ____ each other – there is a small gap between them called a _____. A signal is sent from one _______ to the next by a _______ transmitter across the synapse. These transmitters are then ________.

Words – chemical, synapse, neurone, touch, destroyed

03/02/15HomeostasisHomeostasisHomeostasis means “controlling internal conditions”:

Waste products that need to be removed + how

CO2

Urea

Internal conditions that need controlling + how

Temperature

Ion content

Water content

Blood glucose

Produced by respiration, removed via lungs

Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder

Increased by shivering, lost by sweating

Increased by eating, lost by sweating + urine

Increased by drinking, lost by sweating + urine

Increased and decreased by hormones

03/02/15FertilityFertility

In normal circumstances natural hormones are responsible for releasing the egg and for thickening the lining of the womb. These hormones are produced by the pituitary gland in the brain and in the ovaries.

1) …stimulate the release of eggs 2) …inhibit the release of eggs

The amount of glucose in our blood is an example of a process controlled by hormones. Hormones are “chemical messengers”, produced by glands and tranposrted by blood. Another example of a process controlled by hormones is the menstrual cycle, where hormones can...

03/02/15FertilityFertility3 hormones are involved in the menstrual cycle: oestrogen, LH and FSH. Here’s how:

Step 3: LH stimulates the release of the mature egg in the middle of the menstrual cycle. The oestrogen inhibits further production of FSH

Artificial fertility:

1) To INCREASE fertility FSH is given to stimulate maturation of eggs.2) To DECREASE fertility oestrogen is given (“The Pill”) to inhibit FSH

production stopping eggs from maturing.

Step 1: FSH produced by the pituitary gland causes both an egg to mature and the ovaries to start producing oestrogen

Step 2: The rising levels of oestrogen cause the pituitary gland to stop producing FSH and produce LH instead

03/02/15Birth Control pillsBirth Control pills“The pill” is one method of birth control. Originally, birth control pills contained large amounts of _________ to inhibit the ________ of an egg by stopping the pituitary gland from producing _____. These pills had many adverse ____ ______.

Progesterone-only pills are more common now and have fewer side effects.

Words – side effects, oestrogen, maturing, FSH

02/03/15IVFIVFSome couples cannot have children naturally. In-vitro fertilisation (IVF) can help. Here’s how it works:

1. FSH and LH are given to the mother to stimulate the release of mature eggs. They are removed from the womb and placed in a solution of oxygen and water to keep them alive

2. Sperm is added

3. The fertlised egg is allowed to grow into an embryo (a group of 4-8 cells)

4. Usually 3 of these embryos are transferred back into the uterus

02/03/15Plant Growth IntroductionPlant Growth IntroductionPlants produce hormones to control and coordinate growth:

02/03/15Plant HormonesPlant HormonesThe growth of roots and shoots is controlled by hormones:

In the roots hormones slow down growth of the cells in the lower region, which makes the root bend down.

In the shoots the hormone auxin is “destroyed” by light, so the shoot will bend towards the light as the cells on the shaded side grow quickest.

02/03/15Some DefinitionsSome Definitions

Shoots grow towards light (positive phototropism) and against gravity (negative geotropism).

Roots grow away from light (negative phototropism) and in the direction of gravity (positive geotropism).

02/03/15Artificial Plant HormonesArtificial Plant HormonesHormones can be used to help plant growth and the development of fruit:

1) Auxin

This hormone helps fruit to develop

2) Ethene

This hormone helps fruit to ripen

Other uses include rooting powders (to help root development), control of dormancy and weedkilling.

02/03/15Researching new drugs: An introduction to Researching new drugs: An introduction to thalidomidethalidomide

Mat Fraser, comedian and actor

Tony Melendez, guitarist

02/03/15Developing new drugsDeveloping 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.

02/03/15Researching new medicinesResearching new medicinesBefore new drugs can be approved they have to go through three stages. What are the advantages and disadvantages of each stage?

3. Is it safe for humans? Human volunteers are tested on.

1. Is it toxic? Tests are done on cells

2. Is it safe for animals? Animal tests are carried out

02/03/15PlacebosPlacebosClinical 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...

02/03/15DrugsDrugs

Why do people use illegal drugs?

02/03/15Cannabis: Pros and consCannabis: Pros and consIn January 2004 cannabis was changed from a class B drug to a class C drug. Some people think that Cannabis should be made legal. What are the pros and cons of cannabis?

Pros:

Cons:

02/03/15Drugs Research ProjectDrugs 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) Choose one drug and discuss how it affects the human body

02/03/15Other drugsOther drugsDrug Effect on

activitiesAbnormal behaviour

caused

Caffeine/ other stimulants

Alcohol

Paracetamol/ other painkillers

Reactions could become faster

Highly strung, leads to exhaustion

May make you drowsy, you shouldn’t drive

Leads to depressant effects on the nervous system

May make you drowsy, you shouldn’t drive

Side effects include dizziness or itchiness

Overall, the effect of these legal drugs can be greater than the effect of illegal drugs simply because more people use them.

02/03/15SteroidsSteroidsSteroids are drugs that are used to boost athletic performance. They’re banned and using them will lead to disqualification from competing.

This picture isn’t real…Ben Johnson, who ran the 100m in 9.79 seconds in 1988 but had his Olympic gold medal stripped away from him after testing positive for steroids.

02/03/15AdaptationAdaptation

Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:

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02/03/15Extreme environmentsExtreme environments

Deep sea volcanic vents

Mountains

The Arctic

02/03/15CompetitionCompetitionAny living species competes with each other. They may compete for:

- Living space

- Food

- Water

In addition to this competition, the population of a species can be affected by predators, disease, migration etc

Get off my land

Yum!

02/03/15Extinct SpeciesExtinct Species

Dodo

Sabre-toothed tigers and mammoths

What factors have caused these species to become extinct?

02/03/15Endangered SpeciesEndangered Species

What factors have caused these species to become endangered?

02/03/15Pollution IndicatorsPollution Indicators

Lichens in very clean air

Lichens in clean air

Lichens in slightly dirty air

Lichens can be used as air pollution indicators:

02/03/15Pollution 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:

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Measuring Environmental ChangesMeasuring Environmental Changes

Recording temperature changes

Measuring rainfall Recording oxygen levels

02/03/15BiomassBiomassPlants use glucose from photosynthesis to produce starch and cellulose. This plant material is called “biomass”:

02/03/15Food 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

02/03/15Pyramids 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

02/03/15Energy 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

02/03/15Recycling 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

downAbsorption

02/03/15The Carbon CycleThe Carbon Cycle

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

02/03/15VariationVariation“Variation” is the name given to differences between individuals of the SAME species.

Variation is due to GENETIC or ENVIRONMENTAL causes. For example, consider dogs:

1) Ways in which they are the same:

2) Ways in which they are different:

02/03/15Sexual ReproductionSexual Reproduction

The human egg and sperm cell contain 23 chromosomes each.

When fertilisation happens the egg and sperm fuse together to make a single cell. This cell has 46 chromosomes (23 pairs) and continues to grow.

02/03/15Genes, Chromosomes and DNAGenes, Chromosomes and DNA

02/03/15An example - Boy or Girl?An example - Boy or Girl?

X Y X

XX XYGirl Boy

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Father

Mother

Son

Daughter

Boy or Girl?Boy or Girl?

03/02/15Sexual vs. Asexual reproductionSexual vs. Asexual reproductionSexual reproduction:

•2 parents are needed

•Offspring will have “pairs” of chromosomes

•This will cause genetic variation

Asexual reproduction:•Only 1 parent needed

•Offspring are GENETICALLY IDENTICAL to parent (“clones”) “Snuppy” – the

first cloned dog (Aug 05)

03/02/15Cloning PlantsCloning PlantsPlants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples:

1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________.

2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop.

Words – clones, damp, independent, roots, identical

03/02/15Cloning Plants by tissue cultureCloning Plants by tissue culture1) Scrape off a few cells from the desired plant

2) Place the scrapings in hormones and nutrients

3) 2 weeks later you should have lots of genetically identical plants

03/02/15Cloning AnimalsCloning AnimalsMethod 1 – “Embryo transplants”

A developing embryo is “split” before the cells specialise and the identical embryos are implanted into host mothers.

03/02/15Cloning AnimalsCloning AnimalsMethod 2 - Fusion

Host mother Clone

03/02/15Uses of Genetic EngineeringUses of Genetic Engineering

With genetic engineering I can produce milk that contains:• Extra protein• Lower levels of cholesterol• Human antibodies

Genetic engineering can also be used to grow bigger crop yields and to develop plants that are resistant to pesticides and herbicides.

03/02/15Genetic engineering - InsulinGenetic engineering - InsulinStep 1: Using enzymes “cut out” the part of the human chromosome that is responsible for producing insulin.

Step 2: Using another enzyme cut open a ring of bacterial DNA. Other enzymes are then used to insert the piece of human DNA into it.

Step 3: Place it into a bacterium which will start to divide rapidly. As it divides it will replicate and make millions of them, each with the instruction to produce insulin. Commercial quantities of insulin can then be produced.

03/02/15Genetic EngineeringGenetic EngineeringYes No

Should genetic engineering

be allowed?

03/02/15EvolutionEvolution

Charles Darwin (1809-1882)

Evolution is the theory of slow, continual change of organisms

over a very long time. All living things on the Earth have

supposedly developed from the first simple life forms that

arrived 3,000,000,000 years ago.

03/02/15The The ““Evolution TreeEvolution Tree””

Family Hominidae (Great Apes)

Family Hylobatidae (Lesser Apes)

Subfamily Hominidae

Subfamily Ponginae

Tribe HominiTribe Panini

Tribe Gorillini

HumansChimpanzees GorillasOrangutansGibbons

03/02/15Evidence for EvolutionEvidence for Evolution

The Grand Canyon

Fossil records

“Missing links”

Humans with tails

03/02/15EvolutionEvolutionThe main evidence for my theory came

from fossil records. However, these records didn’t exist when I came up with my theory. Also, there was little evidence about how species evolved so few people believed my ideas.

These days scientists understand that the process that causes evolution is called “Natural selection” and it works like this:

03/02/15Natural SelectionNatural Selection1) Each species shows variation:

2) There is competition within each species for food, living space, water, mates etc

4) These survivors will pass on their better genes to their offspring who will also show this beneficial variation.

Get off my land

Gutted!

Yum

3) The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”

03/02/15An example – the peppered mothAn example – the peppered moth

03/02/15Darwin vs LamarckDarwin vs LamarckDarwin wasn’t the first to come up with evolution – he was simply the one credited with explaining how it worked (i.e. Natural Selection). An earlier scientist called Lamarck explained evolution by different means:

Jean Baptiste Lamarck

(1744 - 1829

The giraffe has a long neck because it “stretches” its neck to

reach the food, and these long necks are passed on to their

offspring. Organs which aren’t used will eventually disappear.