Organisation

• 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:

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

• 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:

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.

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)

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

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

• 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

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