B1 OCR gateway science

Fitness and blood pressure 1

Being healthy=being free from disease

Being fit=how well you fufil physical tasks 

Different ways you can measure fitness:






Stamina=Good indication of cardiovascular efficency !!!!The ability of the heart to supply the muscles with oxygen

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Fitness and blood pressure 2

Blood is pumped around the body under pressure:

-Pumped around by contractions of heart muscles

-Contractions increase pressure so they reach every part of the body

-Blood flows through arteries then back through veins to the heart

-Blood pressure at its highest when it contracts (systolic pressure)

-Lowest when the heart relaxes(diastolic pressure)

Blood pressure mmhg

Increase in blood pressure as a result of:





Can be decreased by:exercise/diet

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High blood pressure and heart disease

Smoking can increase blood pressure and consequently lead to hear disease 

1)Contains lots of nasty chemicals such as Nicotene which increases heart rate heart contractions more often lead to increased blood pressure

2)Heart disease any disease that affects the heart and lead to things such as heart attacks 

Poor diet

-If diet high in saturated fat or salt at risk of developing heart disease

Saturated fats:

Cholesterol a fatty substance

saturated fat=high levels of choleterol

to much saturated fat builds up arteries

Forms plaque and narrows arteries 

Reduces the flow of blood leading to a heart attack

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Blood pressure and heart disease continued

High salt levels can increase blood pressure

Some salt as a balanced diet however too much can cause high blood pressure

Increases the risk of damaged arteries 

Build up of plaque can lead to a heart attack

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A balanced diet keeps you healthy!!!!!!

contains all nutrients you need



Proteins-growth and repair of tissues

Vitamins-many functions eg vitamin c prevents scurvy

Minerals- many functions eg iron needed to make haemoglobin for healthy blood

Water-prevents dehydration

Also need fibre to prevent constapation 

Carbohydrates simple sugars like glucose

Fats fatty acids glycerol

Proteins amino acids 

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Balanced diet is according to different people 

Age = children/teenagers=proteinf for growth and repair

Gender= females =iron for loss of blood during periods 

Physical activity=Active people craboyhdrates=energy 

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Diet problems

Eating to little can cause problems:

little protein=kwashikor(swollen stomach)

Developing countries to low in protein

overpopulation protein=rich food

not a lot of money for agriculture therefore difficult to produce foods high in protein

Amount of protein you consume each day=Estimated average daily allowance Ear(g)=0.6xbm(kg)

Eating disorders =poor diet

Caused by low self esteem and desire to be perfect

poor diet can lead to ilnesses such as liver failiure death heart attacks 

Eating to much can lead to obesity 

20%more over your recomended body weight

eating to much=not enough exercise

Risk of Diabeties heart disease and breast cancer

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Infectious diseases

Infectious diseases are caused by pathogens 

Infectious diseases are caused by micro organisms called pathogens four main types:

-Fungi-athletes foot




Symptoms include=

Cell damage by toxins produced by pathogens 

Ginetic disorders faulty genes (non infectious)

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Infectious diseases continued

Malaria for example is caused by a protozoa carried by mosquitoes 

Protozoa is a parasite that lives of ,another organism called a host

Vectors carry without getting it themselves

Mosquitos pick up when they feed on infected animals it passes paraites on every time it feeds of another animal

These diseases often occur in hotter places such as africa as pathogens reproduce faster

poorer countries they dont have the money to treat diseases or educate people

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Four main ways of keeping pathogens out

Skin-stops entering 

The blood-blood clots seal cuts

The stomach-hydrochloric acid kills pathogens in food and drink

The airways-sticky mucus traps bacteria

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Preventing and treating infectious diseases

Immune system:

if pathogens enter body the immune system kills them (white blood cells)

White blood cells constantly travel around the body looking for pathogens

Two lines of attack:

Consuming them white blood cells engulf and digest pathogens

Producing antibodies molecules on the surface of pathogens called antigens

when comes into contact with white blood cell lock onto and kill it 

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New pathogens can take white blood cells a longer time to produce antibodies for and in time can make you very ill

To avoid this you can be immunised(vacinated)against some diseases such as polio and measels

Active immunity  immune sytem makes own antibodies 

Passive immunity antibodies made by other organisms 

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Antibiotics and Antivirals

Antibiotics kill bacteria

They can get rid of bacterial infections

Antibiotics dont kill viruses 

Antivirals stop viruses from reproducing 

They can treat viral imfections no effect against bacteria

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Drugs are substances which change the way the body works

Some are useful eg antibiotics however can be harmful if misused 

Some are addictive drugs where you have a physical need for them if not then will have withdrawal symptoms

Tolerance develops with some drugs = get used to it 

Depressants=alcahol solvents and temazepam slow down brains activitys 

Stimulants eg nicotene ecstasy and caffine increase brains activity

Painkillers such as aspirin and paracetamol block nerve impulses 

Perfomance enhancers anabolic steriods build muscles and help speed 

Hallucanogenics eg LSD distrort whats seen/heard

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Alcohol-depressant drug

Depressant that decreases the activity of the brain

slows down the nervous system

when youre drunk it can have impacts such as:

Impaired judgement

Slurred speech Blured vision


Reaction time is slower therefor you cant drive after drinking

Longterm effects include - Brain and liver damage 

Doctors reccomend no more than 21 units of alcahol 

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Smoking cigarettes:

Carbon minoxide reduces oxygen in blood

Nicotene-addictive chemical

Tar-covers the cillia irritation can cause cancer

Particulates-Small particles build up and cause irritation 

Smoking can cause many illnesses such as heart disease cancer as well as a smokers cough and bronchitus/emphyesema

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The eye


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Eyes jobs

Cornea = refracts light

Iris=contols how much light enters the pupil 

Lens=refracts light focusing it into the retina

Retina=light sensitive part covered in receptors sensitive to light of colours

Optic nerve=carries impulses from receptors to the brain

Blind spot=no recepters cant detect light 

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Eye details

Light travelling into the eye:

Light from object is refracted into the eye by the cornea

The lens then refracts light a bit more to focus it on your retina 

Long sighted=cant focus on nearby objects lens maybe the wrong shape

eyeball maybe to short

Short sighted=cant focus on distant objects lens maybe wrong shape eyeball to long

Binocular vision=see with both eyes eg humans

They have narrow field of vision 

Monocular vision=See with one eye wide field of vision but cant judge distances easily 

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Neurones and reflexes

Neurones are nerve cells that send information around the body as nerve impulses

Nerve impulse is an electrical signal passed among the axon of the neurone

Three types of neurone=sensory/relay/motor

Central nervous system consists of the brain and spinal chord which ultimately organises information

All neurones outside cns make up peripheral nervous system

A change in envrionment is called a stimulus 

Detecting of a stimulus recpetors generate a nerve impulse which travels along sensory neurones

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Reflex actions stop you injuring yourself and are sutomatic so very fast

Conscious brain isnt involved in a reflex arc the sensory neurone connects the relay neurone in the spinal chord

Relay neurone links to correct motor neurone 

Reflex actions have a protective role like pulling your hand back when you tough a burning hot plate

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Maintains a constant internal envrionment 

keeps conditions steady by automatic control systems

Cells can function at their optimum

Involves balancing imputs  with outputs

Water content and body tempretures are all maintained by homeostasis 

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Controlling blood sugar

Insulin controls blood sugar levels

Insulin is a hormone that controls the sugar quantity in the blood

Respiration causes the amount of sugar in the blood to decrease 

insulin is produced by an organ called the pancreas

Insulin is carried in the blood to ther parts of the body

But only affect particular organs called target organs

Travelling by blood is slow and so hormones react more slowly

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Type 1)prancreas cant produce enough insulin 

if blood sugar rises could kill them

controlled carefully by diet

They also need insulin therapy involving an injection of insulin several times a day

Type 2)Cant respond to insulin

limiting sugary foods 

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Plant hormones and growth

Auxins are plant growth hormones

plant growth is controlled by hormones

They control the groth of the shoot and roots and are called Auxins

Auxins are involved in the responses of plants to light and gravity

Auxins why they are needed????

-Plants need light to make food through photsythesis otherwise they die

Plant shoots grow towards and light increasing their survival rate

Also plants require water which is why roots grow downwards 

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Commercial use of plant hormones

selective weedkillers:

plant growth hormones only affects weeds (kills them)

Growing from cuttings with rooting powder

They wont grow but add rooting powder they will produce roots and new plants 

lets growers produce lots of clones 

Controlling the ripening of fruit

Delays the ripening (plant hormones)

Ripening hormones can be added which will ripen fruit for supermarket purposes

Controlling dormacy:

Seeds wont germinate through certain conditions called dormacy so plant hormones will break dormacy 

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Genes and chromosomes

Most cells in the body have a neucleus this contains ginetic info in the form of chromosomes 

Most animal chromosomes come in pairs depending on species as to the pairs human body cell has 23 chromosomes

Chromosomes carry genes different genes control the development of different characteristics eg eye colour 

A gene is a short length of a chromosome

Quite a long length of DNA

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Genes and the environment

Characteristics such as eye colour depend on your genes

There can be different versions of the same gene called alleles

Everybody has different combinations called ginetic variations

Characteristics can be dominant or recessive 

Some inherited from parents eg eye colour

Dominant are eg brown eyes over blue eyes

Blue eyes are a reccesive characteristic 

recesive are only seen where no dominant characteristics to inherit

Is your environment responsible for some characteristics????

environment controls some such as scars 

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