B1

Benefits:

• Stops you from getting ill
• The disease won't be able to spread as easily
• Creates memeory cells for the pathogen 

Risks

• Swelling,redness and feeling ill are short term effects
• Immune system can be weakened if you have some vaccines when already ill

some think immunisation can cause other disorders:

• Measles, mumps and rubella (MMR) has been said to cause autism 

• Drugs that kill bacteria without killing your body cells
• Can kill bacterial infections but not viruses
• Antivirals can be used to treat viral infections they stop viruses rerproducing
• Some bactieria can be nautrally resistant to antibiotics 
• Not finishing a course or taking too many antibiotics can develop resistant strains 
• Resistant strains cannot be killed by antibiotics
• MRSA is an example of an antibiotic strain 

• Caused by cells dividing out of control
• This forms a tumour (a mass of cells)

Benign tumour- Tumour grows till theres no more room ,cells stay where they are, ususlly harmless.

Malignant tumour- Tumour can spread to other sites in the body, are dangerous and can be fatal 

A healthy lifestyle and diet reduces risk of some cancers

• Not smoking reduces chances of lung cancer
• Less processed meat and more fibre reduces colon cancer

• Computers stimulate a humans response to a drug and identify promising drugs.
• drugs are developed , tested on human tissue.
• Develop and test the drugs on animals. The law is to test on two different live mammals. 
• Then they are tested on humans

Testing on humans

• This is called a clinical trial 
• Two groups of patients- one with the drug and one with a placebo 
• A placebo is a fake sugar pill that looks like the drug (placebo affect when people expects the treatment to work so feels better even though the drug wasn't taken)
• Sometimes the drug is tested on the best exsting drug to see how it compares

Blind and double blind trials

• Blind trial is when the patients don't know but scientist  know whos got the drug and placebo
• Double is blind is when scientist and paitent don't know whos got which only those with the data know.

• Some drugs are dangerous if missused so they have to be prescripted
•  addiction is a physical need for a drug a sign of addiction is showing withdrawl symptons when the drug is not taken 
• Tolerance develops with some drugs- the body gets used to having it so a higher dosage is needed to have the same effect.
• Rehabilitation can help someone overcome an addiction (support and help)

Depressants-Alcohol,solvents 

• Decrease brain activity
• slows the responses of nervous system , slow reactions and poor judgement

Stimulants-nicotine,ecstasy,caffine

• increase brain activity and makes you alert, used to treat depression 

Painkillers-aspirin and paracetamol

• reduce painful stimuli in nerve endings

Performance enhancers-anabolic steroids 

• help build muscle and allow athletes to train harder

Hallucinogens-LSD

• Disort what's seen and heard by altering the pathways that the bains sends messages along

Class C - Anabolic steroids and tranquilisers

Class B- Cannabis and amphetamines

Class A- Heroin,LSD and cocaine

Class A is the most serious

• Depressant- reduces the activity of the nervous system 
• Makes people feel less inhibited
• Poisonous- broken down by the enzymes in liver and some products are toxic
• Can cause death of liver cells
• Cirrohosis- Caused by death of liver cells that then form scra tissue that stops blood reaching the liver
• Alcohol cuases dehydration which can damage cells in the body 
• Being drunk can lead to : Impaired judgement,poor balance,slurred pseech blurred vision and sleepiness

• Carbon monoxide reduces carrying capacity of red blood cells if heart doesnt recieve enough oxygen it can lead to heart attack or heart disease
• Tar from cigaretts collects in the lungs some of it is toxic and creates carcinogens (cause cancer) these make mutations in the DNA likely cell devision can go out of control and malignant tumours can form
• Smoking damages the cillia on the trachea, bronchi nd bronchioles it enoucrages mucas, excess mucus cant be cleares bc cillia is damaged so it sticks to air passages causing smokers cough
• Low oxygen caused by carbon monoxide can deprive foetus of oxygen leading to small babies at birth.

• Cornea -refracts light into the eye
• Iris-contorls how much light enters the pupil
• Lens- refracts light and focuses it on the retina
• Retina- is light sensitive and covered in receptors called rods and cones which detect light.
• Rods are sensitive in dim light but cant sense colour
• Cones are sensitive to different coulors but arent good in dim light (red -green colour blindness is due to lack of specialised cone cells)
• Optic nerve- carries impulses from receptors to the brain 

Lens accommodation - when the lens change shape to focus light

Distant objects

• Cillary muscles relaxes
• Suspensory ligaments pull tight
• This pulls the lens into a less rounded shape so light is refracted less

Close objects

• Cillary muscles contract 
• This slackens the suspensory ligaments
• lens become rounded so refract more 

Long sighted- unable to focus on near objects

• Occurs when lens is in the wrong shape and doesn't bend light or eyeball is too short
• The images of near objects are bought into focus behind the retina
• Glasses or lenses with a convex lens can correct it

Short sighted- unable to focus ondistant objects

• Eyeball is too long or lens in the wrong shape and bends the light too much 
• The images of distant objects are bought into focus in front of the retina
• Glases or contact lenses with concave lens can correct it 

The alternative to glasses or contacts is corneal laser surgery 

• In humans
• The brain compares the images of both eyes the more similarities the further away the object 
• This allows us to judge distances well 
• Narrow field of vision (eyes close together)

• CNS consists of the brain and spinal cord
• Made up of three types of neurone- sensory neurones,relay neurones and motor neurones
•  when a stimulus (a change in your environment) occurs your sensory neurones carry the information from the receptors to the CNS, the CNS sends a message to an effector (muscle or galnd) using a motor neurone.the effector then acts 
• Stimulus-sensory neurone-recpetors-CNS-motor neruone-effector
• The job of the CNS is to coordinate the information

• The brain isn't involed 
• The sensory neurone connects to a relay neurone in the spinal cord which links directly to the right motor neurone. 

Eg.

• A bee stings finger
• Pain receptor
• message travels along sensory neurone
• mesage is passed to a relay neurone
• travels along a motor neurone
• message reaches muscle
• arm moves away

• In a motor neurone
• Electrical impulse passed along an axon
• neurons have branched ending so they can connect with other neurones
• Sheath along the axon acts like a electrical insulator (speeds up impulse)
• They're long which speeds up impulse (one long neurone is quicker than lots of short ones)
• Synapse ( connection between tow neurones ) its a small gap 
• the electircal impulse triggers release of transmitter chemicals they diffuse across synapses
• Chemicals bind to receptor molecules in the membrane of the next neurone
• Sets off new electrical impulse

stimulants increase transmitter chemicals so more impulses +more brain activity, Depressants do the opposite.

 the following Inputs and outputs have to be kept steady 

• Carbon dioxide - that you breathe in and let out
• Water content- that you drink have to be balance with what you let out
• body temp.-getting rid of excess heat and gaining heat 

Negative feedback

• Change in environment triggers a response that counteracts (reverses) the changes . eg rise in body temp causes a response to lower it 
• internal environment has to stay at a constant level at which the cells work best
• If the environment changes too much it might not be possible to conteract 

• All enzymes have an optimum temp. (37 in the body )
• thermoregulatory centre in brain ats as a thermostat, contains receptors that are sensitie to blood temp.recieves impulses that give info on skin temp. 
• The brian can respond to this info by changing the body's temp :

when its too hot:

• hairs lie flat 
• Lots of sweat is produced- swear uses heat from skin when it evaporates which cools you down.
•  Vasodilation - Blood vessles on surface of skin widen - more flows near the surface so it can radiate heat to surroundings

When its too cold:

• Hairs stand up- Adds insualting layer to keep you warm 
• little sweat produced
• Vasoconstriction-Blood vessles near surface constrict so less heat can be transferred to surroundings 
• shiver- movement generates heat in muscles

• eating food with carbohydrates puts glucose into blood 
• respiration removes glucose
• level of glucose must be kept steady
• changes in blood glucose are controlled by pancreas using insulin

Blood with high glucose level (insulin is added)

• Insulin is released by pancreas
• Too much glucose and insulin
• Insuling makes liver turn glucose into glycogen
• Glucose removed by liver
• Blood glucose reduced

Blood with low glucose

• Liver turns glycogen into glucose
• glucose is added by liver
• glucsoe leves increase

Diabetes- affects your ability to control your blood sugar levels

Type 1

• Can partly control the conditon by having a controlled diet but need insulin therapy
• Insulin therapy- injecting isulin into the blood several times a day
• Makes sure that glucose is removed from blood quickly once food is digested 
• Stops level of glucose getting too high
• Amount of glucose depends on diet and how active they are.

Type 2

• Where a person becomes resistant to insulin (body cells dont repsond  to the hotmone)
• Can cause sugar level to rise to dangerous levels
• Controlled by limiting intake of foods rich in simple carbohydrates

• Plant growth hormones-control the growth at the tips and shoot and roots
• Move through the plant in solution (dissloved in water)
• Produced in the shoot and diffuses backwards to stimulate the cell elongation process which happens in cells behind the tips
• Promotes growth in the shoot but inhibts gwoth in the root
• Involved in phototropism and geotropism 

• Shoots are positively phototropic (grow towards light)
• when a shoot is exposed to light it accumulated mre auxin on the side thats in the shade
• this makes thec all elongate faster on shaded side to the shoots bend towards the light
• Shoots are negatively geotropic (gorw away from gravit)
• when its gowing sideways theres more auxin on the lower side
• the shoot grows upwards

• Roots are postively geotropic (grow towards gravity)
• a rood growing sideways will grow downwards becuase there will be more auxin on the lower side
• Roots are negatively Phototropic (grow away from light)
• when exposed to light the auxin accumulates on the shaded sides so it grows the opposite way to the light

Plant hormones can be extracted or made artifical copies and can be used for:

1.Selective weedkillers

• Most weeds have broad leaves
• Have been developed from plant growth hormones which only affect broad leaved plants
• disrupts their growth pattern and kills them leaving grass and crops untouched 

2.Cuttings with rooting powder

• Rooting power contains plant hormones
• adding rooting powder to cutting of a plant will make the cutting grow
• enables to make lots of plant copies (clones)

3.Ripening of fruit

• plant hormones can delya the ripening of fruit while on the plant or on transport
• allows ruit to be picked when unripe 
• adding a ripening hormone is added to the fruit so that it is perfect in the supermarket

4. Controlling Dormancy 

• Lots of seeds wont germinate (grow) unless in certain conditions
• This is called dormancy 
• A hormone called gibberellin breaks dormancy 
• They treated siwth gibberellin to make them germinate at times of the year when they wouldn't normally
• Makes sure they all germinate at the same time

• Most cells have a nucleus.
• nucleus contains genetic material in the form of chromosomes
• chromosomes come in pairs different spieces have different amounts of pairs
• humans:23 pairs of chromosomes
• Chromosomes carry genes
• Genes control the development of characteristics
• A gene is a short section of a chromosome 
• A chromosome is long lenth of DNA
• There can be different versions of the same genes which can different charateristics
• Different versions of the same genes are alleles

• Gametes are sperm cells and egg cells
• Body cells are made from 23 pairs of chromosomes fomr eahc pair one was from dad and another from mom 
• when body cells split to from gametes the chrmomsomes also split
• gametes only have 23 chromosomes not 46
• shuffling of chromosomes leads to variation in new generations

Fertilisation

• when the sperm and egg from to create a new cell with 46 chromosomes

Mutations

• Occasionally a gene may buatate- it changes
• this can create new charateristics, increasing variation

Health- lifestyle can affect the risk of disease not just genes

Intelligence- IQ can be based on genes but also upbringing and school life

Sporting ablility- genes can determind potential but training also does

• Alleles are different veriosns of the same gene
• most of the time you have two alleles from each parent
• the version of the characteristic that shows is caused be the dominant allele, the other one is recessive. the recessive alle is only exposed if they're both recessive.
• In diagrams dominant alleles are shown with a capital and recessive with a lower case. 

Homozygous- when you have two of the same alleles

Hetrozygous- when you have two different alleles

Genotype-your gentic makeup -your gene and alleles

Phenotype- characteristics eg blue eyes

• 23 matched pairs of chromosomes in every human body cells
• the 23rd pair are lablled XY
• they decide whether you're male or female

All men have an XY combination 

All women have an ** combination 

a genetic diagram shows that there is a 50/50 chance of having a boy or girl 

• Cystic fibrosis is an example . 
• A carrier and carry the faulty gene but not ahve the disease
• if two carrieers have an offspring they have a change of carrying both of the recessive allele and become a sufferer

Questions to consider

1, should family members be tested to see if they are carriers, is it fair on future partners or children?

2. It right to have children if you're a carrier

3. Is it possible to test a foetus for the condition? if the test is positive is it right to terminate the pregnancy?