Organisation

• Cell organisation

  Organelle = specialised unit in a cell w specific function

  cell = basic building block of all living organisms

  tissue = group of cells working together to perform a shared function

  organ =structure made up of tissues to perform a specific function

  organ system = group of organs w related functions working to perform a certain function in the body
• Enzymes

  -biological catalysts (speed up reactions)

  -required for most chemical reactions in organisms

  -also involved in building up of chemical molecules

  -they are proteins

  -bind with substrates active sites and are complementary so only bind with certain types (lock and key)
• enzymes (temperature)

  -temperature, low temp = fewer collisions between substrate and enzyme, high temp = Active site changes shape enzyme becomes denatured, optimum temp = enzyme works best in body enzymes work best at 37 degrees
• Enzymes (pH)

  -Changing pH can change shape of the active site

  -changing it will affect the charges of the amino acids that make up the enzyme so they no longer attract = change in shape

  -extreme pH can denature enzymes

  -different enzymes have different optimum pHs e.g in stomach HCl is optimum 1.5 to 2.0 pH
• Carbohydrates

  -source of energy, glucose is main respiratory substrate

  -sources: starch in potatoes, rice, wheat, bread etc, sugars in fruit, chocolate, fizzy drinks etc

  -glucose small enough to be absorbed

  -starch is a polymer of glucose so must be broken down by amylase

  -used for respiration, cellulose, cell wall of plants
• Proteins

  -for growth and repair

  -sources: eggs, meat, cheese, nuts + seeds and beans

  -made up of amino acids and are too big do be absorbed 50 - 2000 amino acids long

  -must be broken down by protease in liver
• Lipids

  -For energy, growth, make up parts of cell membranes

  -sources: butter, meats + processed meat, plant oils, fish, nuts + seeds

  -are esters of fatty acids and glycerol

  -to large to be absorbed so are broken down by lipase
• Carbohydrase/amylase

  -brakes down carbohydrates into simple sugars

  -starch (carbohydrate) broken down by amylase into glucose

  -produced in salivary glands, pancreas, small intestine
• Protease

  -breaks down proteins into amino acids

  -produced in gastric glands in stomach, pancreas, small intestine
• lipase

  -breaks down lipids into fatty acids and glycerol

  -produced in pancreas
• bile

  -emulsifies lipids into tiny droplets with larger surface areas for lipase to work on

  -contains hydrogencarbonate, an alkali, to neutralise stomach acid + makes optimum pH for pancreatic enzymes

  -produced in liver
• Digestive system

  Mouth - begins to digest carbohydrates

  oesophagus - muscles contact to move food to stomach

  stomach - begins to digest proteins + small molecules e.g alcohol absorbed

  small intestine - completes digestion of carbs and proteins + begins lipids digestion

  Large intestine - absorbs water and sends undigested foods to rectum
• Benedict’s test

  -test for sugars

  -10 drops of benedicts (irritant) into solution

  -put in water bath

  -blue/green = no sugar

  -orange/red = sugars present
• Iodine test

  -tests for starch

  -add 3 drops of iodine (irritant) to sample

  -blue/black = starch present

  -brown/orange = no starch
• Biuret test

  -tests for proteins

  -add 2cm cubed of biuret to sample and mix

  -lilac = proteins present

  -blue = no proteins

  -can get blurted A and B, A is corrosive and B is an irritant
• emulsion test

  -tests for fats

  -add 2cm cubed of ethanol (flammable)

  -add 2cm cubed of water

  -shake in test tube

  -cloudy = fats present

  -clear = no fats
• pH on amylase RP

  aim - determine rate of amylase in different pHs

  method - In test tubes mix starch and amylase at different phs (and a control one with no amylase), remove a sample every 10 secs, place on spotting tile and do iodine test

  results -record every 10 seconds the colour if blue/black there is still starch present, go until iodine stays orange,

  • 1/t = rate of starch break down by amylase

  graph - plot results and work out the optimum pH
• gas exchange (lungs)

  -absorb oxygen + transfer carbon dioxide (diffusion)

  -Occurs in (lots 350 mil per lung) alveoli and capillaries (cover 70% of alveoli)

  -small but large surface area, one cell thick and good blood supply for gas exchange
• Heart

  -made of cardiac muscle + double circulation system

  -vena cava = deoxygenated blood into (R) ventricle

  -(R) ventricle = pacemaker cells + blood passes to (R) atrium

  -(R) atrium = blood pumped to lungs via pulmonary artery

  -lungs = oxygenate the blood, back to heart via pulmonary vein

  -(L) ventricle = receives oxygenated blood, passes to (L) atrium

  -(L) atrium =pumps oxygenated blood to body via aorta
• Blood vessels

  -capillaries = smallest and very thin for diffusing molecules e.g oxygen, carbon dioxide, glucose + urea

  -artery = oxygenated blood away heart, high pressure, thick + elastic walls, narrow lumen

  -vein = deoxygenated blood to heart, low pressure, thinner walls, wide lumen, valves
• Blood

  -contains plasma, red + white blood cells and platelets

  -plasma = transports CO2, digests food urea and hormones

  -red = transport oxygen

  -white = ingest pathogens + produce antibodies

  -platelets = blood clotting if wounds
• White blood cells

  Phagocytes= 70%, engulf and destroy pathogens (phagocytosis)

  lymphoctyes = 25%, produce antibodies
• CVD (coronary heart disease)

  -coronary arteries supply heart muscle with blood and oxygen

  -caused by build up of cholesterol due to poor diet + lack of excersise

  -if blocked by build up of cholesterol (fatty material) = less oxygen heart receives = heart muscles dies

  -develop chest pains and result in heart attack if untreated
• Statins

  -drug to lower cholesterol in blood by lowering production in liver

  -often give to ppl with CVD or risk if developing, can’t have if pregnant, breast feeding or liver disease

  -long-term, levels will rise again if not taken
• Stents

  -Metal alloy mesh inserted into coronary arteries to hold open allowing blood flow

  -risks depend on age, general health and if patient has had a heart attack wether to get the operation

  -risk of bleeding, heart attack or stroke
• Heart transplants

  -in cases of heart failure, coronary heart disease can lead to this

  -risk that the transplant organ is rejected, increase risk of infection due to immunosuppressant drugs

  -artificial ones used while waiting for transplant
• Communicable

  -transfer from one organism to another

  e.g measles, malaria and food poisoning
• non-communicable

  -not transferred between organisms

  e.g cancer, diabetes, genetic conditions/diseases
• Factors effecting health

  -diet + exercise

  -alcohol and drugs

  -stress

  -life situations
• Cancer

  -Uncontrollable cell division/growth via mitosis

  -groups of cancer cells is a tumour

  -benign = slow growth, don’t spread to other parts of body

  -malignant = fast growth, spreads via bloodstream to other tissue invading them making a secondary tumour (metastasis)
• Causes of cancer

  -genetic factors

  -carcinogens damage DNA causing mutations

  -risk factors : smoking, alcohol, UV radiation (sunbathing), diet (fats and salt), chemical carcinogens
• Xylem

  -transpiration

  -transports water and minerals from roots to leaves

  -made of vessels (dead cells), form a hollow tube strengthened by lignin

  -doesn’t require energy
• Phloem

  -translocation (up and down)

  -transports sugars and amino acids in water needed for growth, seeds and storage

  -sieve tubes = no nucleus and cytoplasm connects to next cell

  -companion cells = provide energy for translocation
• plant structure

  Waxy cuticle= waterproof so water isn’t lost via evaporation

  upper epidermis= transparent allow sunlight through

  palisade mesophyll= many chloroplast for photosynthesis

  spongy mesophyll= lots of air pockets for gas exchange to help photosynthesis

  Lower epidermis

  guard cells + stomata = control water loss via transpiration
• Transpiration factors

  Temp = increase, water evaporates faster so more water movement increases

  humidity = decrease, decrease in concentration of water outside increases diffusion

  air movement = increase, it removes water vapour more so diffusion increases

  light intensity = increase, rate of photosynthesis increases so more water leaves stomata