• Cells - basic building blocks of all living organisms (e.g. muscle cells)
  • Tissues - a group of cells with a similar structure and function (e.g. muscle tissue)
  • Organs - tissues working together to perform a specific function (e.g. the heart)
  • Organ systems - organs working together to form an organism (e.g. circulatory system)

Enzymes = biological catalysts (increases speed of reaction without being used up.

Enzymes have an optimum temperature and an optimum PH. If it temperature is too high/PH is too high or low, the enzyme changes shape (denatures) and the substrate no longer fits the active site.

The 'lock and key' model shows how an enzyme works:

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Digestive enzymes:

  • Carbohydrases (amylase) convert carbohydrates into simple sugars - made in salivary glands, pancreas & small intestine
  • Proteases convert proteins into amino acids - made in stomach, pancreas & small intestine
  • Lipases convert lipids into glycerol and fatty acids - made in pancreas & small intestine
  • Bile (not an enzyme)  neutralises stomach acid and emulsifies (breaks down) fats.

Digestive system:

  • salivary glands - produce amylase + saliva
  • oesophagus 
  • stomach - pummels food, produces protease, produces acid to kill bactera + give right PH
  • liver - produces bile
  • gall bladder - stores bile + released into small intestine
  • pancreas - produces protease, amylase + lipase to release into small intestine
  • small intestine - digetstion is completed + food is absorbed into blood
  • large intestine - where excess water is absorbed
  • rectum - where faeces (mainly indigestable food) is stored
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  • Trachea - rings of cartilage protecting the airway, carrying air to/from lungs
  • Bronchioles - splits into multiple pathways to carry air to/from all the alveoli
  • Alveoli - maximise surface area for efficient gas exchange
  • Capillaries - blood vessels next to alveoli where oxygen diffuses into the blood and carbon diffuses out
  • Diaphram - moves down for inhalation and up for exhalation

Gaseous exchange:

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The pathway of the blood: Right atrium - Vena cava - Right ventricle -  Pulmonary artery - Lungs - Pulmonary vein - Left atrium - Left ventricle - Aorta - Body.

Blood consists of:

  • Plasma - transports CO2, hormones & waste
  • Red blood cells - carries oxygen
  • White blood cells - part of the immune system
  • Platelets - clump together to form blood clots/scabs

Blood vessels:

  • Artery - carries blood away from the heart, high pressure
  • Vein - carries blood to the heart, low pressure, hve valves to stop backflow
  • Capillary - involved in exchange of materils at tissues, very low pressure, one cell thick

Coronary arteries = carry oxygenated blood to the cardiac muscles.

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Cardiovascular disease = disease of the heart or blood vessels

Faulty heart valves:

  • cause - valves dont open or close properly
  • effect - blood can leak or flow the wrong way
  • treatment - biological valve transplant or mechanical valve

Coronary heart disease:

  • cause - build up of fatty substances in coronary arteries
  • effect - oxygenated blood can't get to cardiac muscle
  • treatment - stents (inserted into blocked artery to open it up) or statins (drugs that lower harmful cholesterol)


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Communicable = it can spread. Non-communicable = cannot spread

Different types of disease can interact:

  • problems with immune system - increased chance of catching communicable diseases
  • cancer can be triggered by a virus
  • mental health issues can be triggered from severe physical health problems

Risk factors (linked things to increase the likelihood of a person developing a disease):

  • smoking
  • obesity
  • excesive drinking of alcohol
  • smoking whilst pregnant
  • exposure to radiation
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Caused by uncontrollable cell growth and division.

Benign tumour = Contained in one area of the body - not cancer

Malignant tumour = Invades tissues and spreads to different parts of the body through the bloodstream.

Risk factors:

  • smoking - lung cancer
  • obesity - bowl, liver, kidney cancer
  • UV exposure - skin cancer
  • viral infection - hepatitis B&C can lead to liver cancer
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  • Epidermal tissue - covers whole plant 
  • Waxy cuticle - reduces water loss by evapouration.
  • Guard cells & stomata - open and close to control water loss & allow for gas exchange
  • Palisade mesophyll - packed with chloroplasts containing chlorophyll, where most photosynthesis happens
  • Spongy mesophyll - contains air spaces to allow gases to diffuse in and out
  • Xylem - transport water + mineral ions from roots to stem and leaves
  • Phloem - transports dissolved sugars from leaves to rest of plant for use or storage
  • Meristem tissue - where new cells and roots are made
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Phloem tubes: 

  • columbs of elongated cells, small pores at end walls allow cell sap to flow
  • transport food substances in both directions
  • process called translocation

Xylem tubes:

  • made of dead cells joined end to end, no end walls
  • carry water and mineral ions from roots to stem and leaves
  • process called transpiration

Transpiration = The rate at which water is lost from the leaves of a plant. It is affected by 4 main things:

  • Light intensity - brighter:faster rate
  • Temperature - warmer:faster rate
  • Air flow - better air flow:faster rate
  • Humidity - drier air:faster rate
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