Biology

All the revision i need to know from Y7 to Y9 for Biology sats

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  • Created by: Zen91297
  • Created on: 01-06-12 15:46

Diet And Metabolic Rate

Protein - the body uses protein for growth, cell repair, and cell replacement

Metabolic Rate- the speed at which all the chemical reactions in the body cells are carried out

Why The Body Needs Fats- the body needs fats to keep warm and to store and release energy

Carbohydrates- if you excercise a lot you'll need a lot of energy, energy comes from eating carbohydrates

Important Food Groups - the body needs carbohydrates, fats, protein, and fibre, as well as minerals and vitamins

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Factors Affecting Health

In order to lose weight we need to eat less fats or carbohydrates, we also need to do more exercise

If someone is malnourished it means their diet is unbalanced

Inherited factors can affect our health, for example our metabolic rate can cause an underactive thyroid gland which can lower the metabolic rate and cause obesity. Also inherited factors can increase cholesterol level which can increase the risk of heart disease

People who exercise regularly are likely to be healthier than people who do little exercise because exercise increases the energy used and reduces the amount of fat, it boosts the metabolic rate and also builds muscle 

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Fighting Disease

Antibodies protect the body from pathogens by locking onto and killing the pathogens, the antibodies are produced by white blood cells

White blood cells attack pathogens by consuming them they can also attack pathogens by produucing antitoxins which counteract the toxins produced by the pathogens

The body protects itself from pathogens by skin, hairs and mucus in the respiratory tract stop pathogens from getting into the body, Platelets help the blood clot quickly and seal wounds , this stops pathogens from getting through cuts

Bacteria can make us feel ill by damaging our cells and producing toxins

Viruses can make us feel ill by replicating themselves inside body cells using the cells machinery, this makes the cell burst which releases all fo the new viruses, its the actual cell damage that makes us feel ill

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Fighting Disease- Vaccination

Vaccines contain small amounts of dead or inactive  microorganisms

The MMR vaccine protects people from Measle, Mumps and Rubella 

Disadvantages of vaccinating people against disease - Vaccines dont always work , Vaccines can sometimes cause bad reactions

Benefits of Vaccinating people against disease- Vaccines have helped to control diseases that were once really common, if we vaccinate a large percentage of the population epedemics can be prevented

vaccinations protect people from disease -the dead or inactive microorganisms  that the vaccine contains carry antigens. White blood cells then create antibodies in response to these antigens, so if the same type of microorganism ever appears again the white blood cells can quickly mass-produce teh smae antigens to kill the microorganisms

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Fighting Disease - Drugs

Antibiotic- resistant strains of bacteria develop when a bacterial ccell mutates and the mutation causes it to become resistant to an antibiotic. this trait is then passed on to future generations as the cell multiplies

it is a problem when bacteria become antibiotic resistant because resistant bacteria can survive and reproduce because people arent immune to them and theres no treatment. Because of this population will increase & it'll spread rapidly

It is difficult to develop drugs to kill viruses because viruses reproduce using our bodycells this means its difficult to produce drugs that just destroy the virus without killing the body cells too

we  could investigate the action of different antibiotics by soaking paper discs in different antibiotics and place them on the jelly or the petridish. anitbiotic resistant bacteria will continue to grow around the paper discs but non-resistant strains will die

Painkillers only help reduce symptoms rather than tackling the cause of the illness, anitbiotics actually kill the bacteria

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Fighting Disease - Past and future

Semmelweis cut death rates by making doctors wash their hands in an antiseptic solution , basic hygiene is important in the prevention of disease. workers and visitors in hospitals are encouraged to wash their hands often to help limit the spread of disease

its hard to vaccinate against diseases that are caused by viruses because mutations can cause changes to their DNA which can lead to them having different antigens

A new strain of Bacteria could cause an epidemic because it might be a strain we have not encountered before, meaning nobody would be immunee to it and so the bacteria could spread really rapidly through the population causing an epidemic

Semmelweis cut the death rate from puerperal fever in hospitals in the 1840's by making doctors wash their hands in an antiseptic solution

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The Nervous System

An Effector can be Muscles or Glands, they respond to signals fromm the central nervous system, that come via motor nuerones. muscles contract in response and glands secrete hormones

Our five sense are organs are 

        -Eyes - they have receptors sensitive to light

       - Ears - they have receptors sensitive to sound and changes in position

      - Nose - it has smell receptors sensitive to chemical stimuli

     - Tongue - it has taste receptors sensitive to chemical stimuli such as bitter, salt,sweet

the central nervous system is where all the information from sense organs are sent, reflexes and actions are also coordinated here the three types of nuerone are - sensory nuerones, they carry signals from sense organs to the central nervous systems relay neurones carry signlas from sensory nuerones to motor nuerones motor nuerones carry signals from the central nervous system to the effector muscles or gland

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Synapses and Reflexes

a synapse is the connection between two neurones

what is a reflex arc - a stimulus is detected by receptors and impulses are sent along a sensory nuerone to the central nervous system. the impulse is then sent along a relay neurone and then a motor neurone. from the motor neurone the impulse goes to an effector. the effector responds by contracting if its a muscle or by releasing hormones if its a gland

a nerve impulse passes along a synapse by the nerve impulse transferring the chemicals which diffuse across the gap. these chemicals then set off a new electrical signal in the next neurone

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Hormones

Hormones travel around the body by glands secreting hormones directly into the blood. the hormones are carried in the blood plasma to particular cells  ( called target cells) in particular places

a hormone is a chemical messenger which travels in the blood to act on target cells 

Compared to nervous responses, hormones have a slower action and act for a longer time. Nerves on the other hand produce fast responses which act for a very short time on a very precise area

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The Menstrual Cycle

Oestrogen causes the pituitary gland to produce LH , Oestrogen inhibits the further release of FSH- this is what oestrogen does in the menstrual cycle

the name of the hormones involved in promoting the release of an egg during the menstrual cycle is FSH ( follicle stimulating hormone), LH ( luteinising hormone) and oestrogen 

FSH causes an egg to mature in one of the ovaries

FSH stimulates the ovaries to produce oestrogen

in the menstrual cycle the uterus lining breaks down for ( 1-4 days) then on  days ( 4 to 14) the lining builds back up to recieve an egg which is released from the ovaries around day 14. the lining is maintained from day 14 . the lining is maintained from day 14 to 28. if no fertilised egg lands before about 18 dayys the lining start to break down and the cycle begins again

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Controlling Fertility

oral contraception can contain hormones such as oestrogen and progesterone

disadvantages of the pill are  - it isnt 100% effective, it can cause side effects,  doesnt protect you from STD's

Process of IVF- before eg collection the woman is given FSH and LH to stimulate egg production, eggs are then collected from the womans ovaries and fertilised in a lab using the mans sperm , the fertilised eggs are then grown into embryos once the embryos are tiny balls of cells one or two of them are transferred to the womans unterus

disadvantages of IVF- some women have strong reactions to the hormones and experience side effects. increased risk of cancer, increased change of multiple births . 

Taking oral contraceptives containing oestrogen keeps the oestregen levels high . this inhibits the production of FSH which stops eggs from maturing

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Plant Hormones

gravitropism is the growth of a plant in response to gravity. its controlled by the hormone auxin. when a shoot tip is exposed to light more auxin accumulates on the side thats in the shade that the side thats in the light this makes the cells elongate faster on the shaded side so the shoor bends towards the light

gravitropism causes plant roots to grow towards gravity and plant shoots to grow away from gracity

weed killers containing plant growth hormones disrupt the normal growth patterns of broad leavved plants( weeds) leaving grasses, and cereal crops untouched this is how weed killers containing growth hormones work 

The factors plants are most sensitive to are - gracity, light , and moisture

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Homeostasis

we will produce less urine on a hot day or if we do a lof of excerise because ; in both situations we will lose more water through sweat, so when we do urinate it will have a smaller volume and will be more concntrated than normal

Our body temperature must be maintained at a certain level to provide the best temperature for our enzymes to work at 

four internal conditions that our body needs to keep constant to survive

Ion content of the blood

Water content of the blood

Body Temperature

Blood Sugar level

homeostasis means maintaining internal conditions within the body

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Drugs

some athletes take performance enhancing drugs because they might be more concerned about their performance than about the tisks associated with taking performance ehancing drugs. they may also argue that as other athletes have access to different training facilities coaches and equipment which all enhance performance, drugs are no different 

people might be against athletes taking performance enhancing drugs because some people think its unfair, and athletes may not be fully aware of the health risks

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Testing Medicinal Drugs

The problem of using thalidomide to treat morning sickness, resulted in abnormal limb development causing some babies to be born with physiical deformities

a double blind trial is when neither the doctor not the patient knows whether they are getting the drug or the placebo until the results are gathered

the placebo effect is when a patient believes they are using an effective drug ( like in a clinical trial) they may start to feel better even if the drug doesnt actually do anything

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recreational drugs

excessive and long term alcohol consumption can cause liver disease, and brain damage

Tobacco can cause problems to UK society such as

The NHS has to spend a lot of money treating people with lung diseases caused by smoking

the economy is affected as people who are ill as a result of smoking cost businesses money by taking time off work

someone who has used a recreational drug may move onto harder drugs because the use of cannabis may create a desire to try harder drugs. Cannabis is a gateway drug. Genetically certain people are more likely to take drugs, so people who try cannabis may also be more likely to try harder drugs

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Olivia Mullan

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Zen91297

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