Biology

Revision cards for B1, OCR gateway 

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Fitness

Fitness= The ability to perform everyday tasks

Health= Complete state of mental, social and physical health not just the absence of disease

Fitness profiles measure:

  • strength
  • Speed
  • Stamina
  • Flexibility

Stamina is a good indication of Cardiovascular efficiency

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Blood Pressure

Blood Pressure

  • Blood is pumped around the body because of contractions of the heart which increase pressure
  • Blood leaves heart through arteries, it then flows back to heart through veins, pressure gets lower as it runs through the system
  • Systolic pressure= heart at highest pressure- contracts
  • Diastolic pressure= pressure at its lowest-  relaxes
  • Measured in mmHg
  • healty person systolic shouldn't be higher than 135 and diastolic about 85
  • factors that contribute the blood pressure; Diet with too much salt, being overweight, too much alcohol, not enough exercise, age
  • If too low= poor circulation, tissues don't get all food and oxygen that they need= dizziness and fainting
  • If too high= blood vessels burst, strokes, brain damage, kidney damage
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Respiration

Respiration is the process of releasing energy from glucose which happens constantly in every cell

Aerobic= needs plenty of oxygen

  • most efficient way to release energy from glucose
  • Glucose+Oxygen-------> Carbon Dioxide+Water (need to know chemical)

Anaerobic= No oxygen

  • Happens when do hard exercise and can't make enough respire aerobically
  • Glucose------> Lactic Acid+Energy
  • Lactic acid build up leads to an oxygen debt
    • muscles are still short of oxygen and need extra oxygen to break down lactic acid, so have to breath hard after doing exercise to repay the debt
    • Lactic acid must be taken to the liver to be broken down so heart rate remains high
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Healthy Eating

Carbohydrates- Provide energy (e.g. Glucose) made of simple sugars

Fats- Provide energy and act as an energy store and provide insulation, made up of fatty acids and Glycerol

Proteins- Growth and repair of tissue, made of animo acids

Vitamins- Various functions, e.g Vitamin C to prevent Scurvy

Minerals- Various functions e.g. Iron is needed to make Haemoglobin

Water- Need constant supply to replace water lost through urinating, breathing, sweating

Energy and Nutrient needs vary between people- Age (young people need more protien to grow, old people need more calcium to keep bones strong) Females need more Iron, Active people need more energy and protien

Some people choose a different diet- Religion, Personal, Medical

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Diet Problems

Too Much Food= Obesity

  • too much sugary of fatty foods and too little exercise
  • increases risk of diabetes, arthritis, high blood pressure, coronary heart disease and some forms of cancer

Under eating can also cause problems

  • too little protein= Kwashiorkor
    • symptom= swollen stomach, common in parts of world where protein rich foods are too expensive to buy
  • psychological disorders cause under-nutrition= Anorexia and Bulimia
    • Can lead to other illnesses like kidney and liver failure, muscle wastage, heart attacks, low blood pressure, mineral deficiencies

Body Mass Index indicates if your under or over weight BMI= Body mass

            (Height)2

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Digestion

Big molecules are broken down into smaller ones and go into blood

First food is physically digested by chewing it and churning in the stomach, then chemical digestion breaks down the molecules which are too big, uses enzymes

  • Carbohydrases break down carbohydrates (e.g. Starch) Into simple sugars in the mouth and small intestine
  • Proteases convert proteins into animo acids in the stomach and small intestine
  • Lipases convert fats into fatty acids and glycerol in the small intestine

Stomach acid lowers pH to help enzymes wok

Bile in the stomach neutralises acid from stomach and emulsifies fat

Small Molecules can diffuse into the blood- Glucose and animo acids diffuse into blood plasma, fat digested products have to diffuse out the gut into a fluid called lymph from the lymphatic system and emptied into blood.

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Infectious Disease

Fungi- athletes foot, Bacteria- Cholera, Viruses- Flu, Protozoa- Dysentery

Malaria is caused by a protozoan, mosquitoes are vectors (carry disease without getting it themselves) When they feed on another animal they infect it

  • Can reduce their infection by: Areas where they lay their eggs can be sprayed with insecticides, Fish can be introduced to eat the Larvae, People can be protected using nets

Immune system deals with Pathogens- White blood cells are most important

  • Consume them- Engulf cells and digest them
  • Producing Antitoxins- counter effect any poisons produced by bacteria
  • Producing Antibodies- Every pathogen has unique molecules on the surface of its cells- Antigens, when white blood cells come across foreign antigens they make antibodies which attack the antigens the person is naturally immune
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Immunisation

Immunisation stops you getting infections- involves injecting dead or inactive micro organisms into the body, they carry antigens even though they are harmless so the body makes antibodies to attack them.

Active immunity= when the immune system makes its own antibodies after being stimulated by a pathogen, naturally immune and artificially ammune (immunisation) its permanent

Passive immunity= where you use antibodies made by another organism e.g. mother to baby in breast milk- temporary

Benefits- stops you from getting ill, disease won't spread easily

Risks- short term side effects (e.g. swelling) can't be vaccinated if already ill, could cause disorders

Antibiotics= drugs that kill bacteria and fungi but not viruses. Some bacteria can become resistant to antibiotics e.g. MRSA (hospital 'superbug')

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Other Health Conditions

Vitamin deficiency- e.g. scurvy if don't get enough Vitamin C

Mineral deficiency- lack of iron leads to anaemia

Genetic inheritance of disorders e.g. red-green colour blindness, haemophilia

Body disorders are caused by body cells not working properly e.g. diabetes

Cancer is caused by body cells growing out of control

  • Forms a tumour=mass of cells can either be benign or malignant
  • Benign-tumour grows until there's no more room, isn't normally dangerous
  • Malignant-tumour grows and can spread to other sites in the body, dangerous and can be fatal
  • Leading a healthy lifestyle can reduce some risks of some cancers
    • Not smoking reduces risk of lung cancer
    • wearing sun cream protects from skin cancer
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Development of drugs

  • Computer models are made to stimulate humans response
  • Tested on human tissue but can't use human tissue to test drugs that affect the whole body 
  • last step= test the drug on animals, 2 live mammals in the UK
  • After tested on animals its tested on humans
    • clinical trial
    • two groups of patient- one is given the new drug and one is given the placebo (a sugar pill which looks like the new drug but doesn't do anything
    • clinical trials are blind so the patient doesn't know what they are getting
    • they are often double blind so the scientist doesn't know either
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Drugs: Use and Harm

  • Alter the way in which the body works, some are medically useful (penicillin) and some are dangerous if misused
  • Some people get addicted to drugs and have withdrawal symptoms
  • Tolerance= when the body gets used to have a certain drug so you need a higher dose to get the same affect
  • Depressants- alcohol and tamazepam, decrease the activity of the brain slows down responses of the nervous system
  • Stimulants- nicotine, ecstasy and caffeine, increase activity of the brain by increasing amount of transmitter substance at some neurone synapses making you more alert and awake
  • Painkillers e.g. Aspirin- reduces the number of painful stimuli at the nerve endings near and injury
  • performance enhancers- anabolic steroids, are taken by athletes to build up muscle
  • Hallucinogens- cannabis and LSD distort what is seen and heard by altering the pathways the nerve impulses normally travel along
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Some drugs are illegal

  • Class A are most dangerous- heroin, LSD, Ecstasy and cocaine, Lengthy prison sentence
  • Class B- cannabis and amphetamines
  • Class C- anabolic steroids and tranquillisers
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Alcohol

Alcohol is a depressant drug- reduces activity of the nervous system

  • makes people feel less inhibited (many people think it helps them socialise and relax)
  • Alcohol is poisonous
    • normally the liver breaks down the toxic alcohol into harmless products but drinking to much kills the liver cells forming scar tissue preventing the blood reaching the liver- Cirrhosis, the liver can't do its normal job at cleaning the blood
    • Causes dehydration which can damage other cells in the body
    • being drunk leads to impaired judgement, slurred speech, poor balance, poor coordination, blurred vision, sleepiness
  • 21 units of alcohol for a man a week
  • 14 units of alcohol for a woman a week
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Smoking

  • CARBON MONOXIDE- stops the haemoglobin carrying as much oxygen
  • NICOTINE- stimulant drug which makes smoking addictive
  • TAR- covers the cilia preventing them from moving mucus and bacteria out of the lungs
  • PARTICULATES- accumulate in lung tissue causing irritation

Smoking leads to lots of illnesses

  • disease of the heart and blood vessels resulting in heart attacks and strokes
  • causes lung, throat, mouth and oesophageal cancer
    • Tar collects in the lungs its full of carcinogens which cause cancer and make cell mutations in DNA more likely
  • causes servere loss of lung function leading to emphysema and bronchitis
    • destroys cilia and epithelial tissue lining the trachea
    • irritates the bronchi and bronchioles which causes mucus to be produced
  • lungs lose elasticity causing emphysema
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The Eye

  • The CORNEA refracts light into the eye
  • The IRIS controls how much light enters the pupil
  • The LENS focuses the light onto the retina
  • The RETINA is the light sensitive part which is covered in receptors called rods and cones which detect light
  • RODS are more sensitive to dim light but can't see colour
  • CONES are sensitive to the colours but are not good in some light
  • OPTIC NERVE carries impulses to receptors in the brain

Focussing on near and distant objects

  • Distant objects- Ciliary muscles relax which allows suspensory ligaments to pull tight making the lens go thin
  • Near objects- ciliary muscles contract which slackens the suspensory ligaments making the lens fat
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Long or Short Sighted

Long sighted people are unable to focus on near objects

  • occurs when the cornea or lens doesn't bend the light enough or the eyeball is too short
  • images are brought into focus behind the retina
  • can use glasses with a convex lens to correct it

Short sighted people are unable to focus on distant objects

  • occurs when the cornea or lens bends too much light or the eyeball is too long
  • the images of distant objects are brought into focus in front of the retina
  • can use glasses with concave lens to correct it
  • Binocular= 2 eyes working together- (like humans) handy when catching prey, allows to judge depth
  • Some animals have monocular vision- wider field of vision as have totally seperate views but can't easily judge depth or speed
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Neurones

Neurones transmit information as electrical impulses around the body

  • electrical impulse is passed along the axon
  • neurones have branched endings so they can connect to lots of other neurones
  • They have a sheath along the axon that acts as an electrical insulator which stops the impulse getting lost and speeds up the electrical impulse
  • They are long which speeds up the impulse
  • The connection between 2 neurones is called the synapse
    • The nerve signal is transferred by transmitter chemicals which diffuse across the gap
    • these chemicals set of a new electrical impulse
    • Stimulant drugs increase the amount of transmitter chemical at some synapses which increases frequency of impulses
    • depressants increase the amount of different transmitter chemical at some synapses which decreases the frequency of impulses which decreases brain activity
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Nervous system and Reflex Actions

The Central Nervous System coordinates information

  • consists of brain and spinal cord
  • when you detect a change in environment your sensory neurones carry information from receptors to the CNS
  • The CNS sends information to an effector along a motor neurone

Stimulus--Receptor--Sensory Neurone--CNS--Motor Neurone--Effector--Response

Reflex actions stop yourself injuring yourself

  • uses electrical impulses for a very quick response, they are automatic so are very quick
  • Have a protective role
  • the concious brain isn't involved in the reflex arc, sensory neurone joins to the relay neurone in the spinal cord which directly links to the motor neurone
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Homeostasis

=containing a constant internal environment

Need to be kept steady so the body can function properly:

  • Levels of CO2- respiratopn constantly produces CO2 which needs to be gotten rid of
  • Water content- you need to balance the water you gain (in food and drink) with the water you urinate out, sweat and breathe
  • Body temperature- need to be able to get rid of excess body tempurature

NEGATIVE FEEDBACK keeps all these things steady

  • changes in the environment trigger a response that counteracts the changes
  • means the internals environment must stay around a norm which cells work best
  • only works within certain limits
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Body Temperature

All enzymes work best at a certain temperature- 37'C

  • Thermoregulatory centre in brain (own personal thermostat)
  • Contains receptors that are sensitive to the bloof temperature

When too hot: Hairs lie flat, lots of sweat is produced (when it evapourates it transfers heat to the environment), blood vessels close too the surface widen allowing more blood to flow near the ssurface and radiate more heat to the surroundings- vasodilation

  • very high temperatures can lead to dehydration and heat stroke

When too cold; hairs stand on end to trap an insulating layer of air to keep you warm, little sweat its produced, blood vessels near the surface constrict- vasoconstriction- so less heat it given to the surroundings, you shiver to generate movement and energy in muscles

  • very low temperatures can lead to hypothermia
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Controlling blood sugar

Insulin controls blood sugar levels

  • eating foods containing carbohydrate puts glucose into the blood from the gut
  • normal  respiration in cells removes glucose from the blood
  • vigorous exercise removes a lot of glucose from the blood
  • levels of glucose in the blood much be kept steady, the changes in blood glucose are monitored and controlled by the pancreas

Blood glucose levels TOO HIGH- insulin is added from the pancreas

Blood glucose level TOO LOW insulin is not added

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Diabetes

=a condition where the pancreas doesn't produce enough insulin

persons blood glucose level can rise to a level that can kill them

can be controlled in two ways

  • avoiding foods rich in simple carbohydrates, and do exerise after eating yo use up extra glucose
  • Injecting insulin into the blood at mealtimes makes the liver remove the glucose as soon as it enters the blood

 The amount of insulin that needs to be injected depends on the person’s diet and how active they are

 Diabetics can check their blood sugar using a glucose monitoring device

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Hormones

Promote sexual characteristics at puberty

  • In men- extra hair, muscles develop, penis and testicles enlarge, sperm production, deepening of voice
  • In women- extra hair, hips widen, development of breasts, egg release and periods start

Hormones control the menstrual cycle

  • Oestrogen- causes the lining of the uterus to thicken ready for egg to implant, Stimulates the release of an egg on day 14
  • Progesterone- maintains the lining of the uterus,
    • when the level of progesterone falls the lining breaks down
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Hormones and contraception

Oestrogen and Progesterone are used in contraception- in the pill

  • If its taken every day the oestrogen levels are permanently high to stop egg release because it inhibits the production of FSH and mimics pregnancy

There is a progesterone only pill which works by stimulating the production of thick cervical mucus which prevents any sperm getting through and reaching an egg

FSH is used to stimulate egg production in fertility treatment

  • Can be taken by women who aren’t producing eggs to stimulate egg development
  • FSH stimulates the ovaries to produce oestrogen
  • Have to be careful with the dose you take as can result in multiple births
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Genes and chromosomes

  • Chromosomes are divided into different regions called genes and each gene codes for a different protein
  • Chromosomes are long lengths of DNA coiled up and a gene is a short section of this DNA
  • Each human cell has 46 chromosomes arranged in 23 pairs
  • Genes are chemical instructions on how to put an organism together
  • Each separate gene is a chemical instruction on how to put a protein together, proteins are important as they control most processes in the body
  • Cells can make proteins by stringing amino acids together in a particular order, 4 kinds of bases A, T, C, G
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Genetic Variation

Gamete formation- making sperm and egg cells in the ovaries or testes

  • Reproductive cells have 23 pairs of chromosomes
  • When reproductive cells split in two some of the fathers chromosomes are grouped with the ones from the mother this shuffling of chromosomes results in a new generation
  • Fertilisation is when the sperm and egg with 23 chromosomes each join up to make a full set of 46 chromosomes
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Another way of genetic variation- mutation

Mutations are changes in the genetic code of the DNA bases which could stop the production of a protein or a new protein may be produced

  • Mutations happen spontaneously when a chromosome doesn’t copy itself properly can have an increased risk if you are:
    •  exposed to nuclear radiation, x-rays or ultra violet light and chemicals called mutagens
  • Mutations are usually harmful- if happen in reproductive cell baby may be abnormal or die
  • If a mutation occurs in body cells it may mutate are multiply in an uncontrolled way (cancer)
  • Very occasionally mutations are beneficial and give an organism a survival advantage
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Characteristics

Most features are determined by both your genes and your environment

  • Health- some people more likely to get some diseases due to genes but lifestyle also affects the risk
  • Intelligence- one theory is you are born with genes determining your maximum possible IQ but whether you get that depends on your upbringing and school life
  • Sporting ability- genes probably determine your potential but training is important;
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Genetic Diagrams

They show the possible genes of an offspring

  • Most of the time you have two of each gene one from each parent
  • If the alleles are different you have instructions for two different versions the characteristic which appears is dominant and the other allele is said to be recessive

Homozygous= two alleles the same

Heterozygous=two different alleles

Dominant uses capital letters, recessive uses small letters

Monohybrid cross= when you breed 2 organisms together to look at one characteristic

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Genetic Diagrams and Disorders

All men= XY

All women= XX

Cystic fibrosis is caused by a recessive allele

  • It is a genetic order of the cell membranes and results in the body producing a lot of sticky mucus in the air passages and pancreas,
  • both parents must be carriers of sufferers to have a child with Cystic fibrosis
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Comments

Kimmy

Full of info, but maybe too much for revision cards. The less info on the page, the more your brain can take in. Still, very useful thank you :)

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