organisation

• Multicellular organisms are made of cells, which are specialised to perform certain roles

  • cells form tissues
  • groups of tissues form organs
  • groups of organs create organ systems
  • many organ systems create a multicellular organism

  the organ system is designd to efficiently digest and absorb foods
• enzymes are known as biological catalysts - they increase the rate of reaction without being used up/changed

  enzymes are made up of long chains of amino acids, which are foded into specific shapes

  the active site of an enzyme is the region of an enzyme where substrate molecules bind and undergo a chemical reaction

  A) substrate

  B) products

  C) substrate

  D) product

  E) active site

  F) enzyme is unchanged, cycle is repeated

  
• rate of reaction for enzymes affected by two things:

  • temperature - at optimum temp, enzymes and substrate will have more kinetic energy, so more frequent successful collisions
  • after, or before, bonds will lose their specific shape (becomes denatured)
  • each type of enzyme will have a different pH
  • if pH is too high/low, bonds will lose their specific shape (becomes denatured)
• DIGESTIVE SYSTEM

  food enters through the mouth, teeth break food into small pieces

  • amylase is produced in saliva - breaks down starch from food into maltose

  the food is sent down to the stomach

  • churns up food and igests proteins with pepsin
  • produces hydrochloric acid - kills bacteria, makes the stomach approximately pH2

  food then sent to the small intestine, where bile and enzymes are released

  • bile is made in the liver, and stored in the gall bladder
  • the bile neutralises acid from stomach to create a suitable pH for enzymes
  • bile emulsifies fats to be easily digested by lipase enzymes
• DIGESTIVE ENZYMES

  • amylase breaks down starch and turns them into maltose (and other sugars). They are made in the salivary glands, pancreas, small intestine
  • protease breaks down proteins into amino acids. They are made in the stomach (pepsin), pancreas, small intestine
  • lipase breaks doen lipinds into fatty acids and glycerol. They are made in the pancreas, small intestine
• LUNGS

  lungs are responsible for gas exchange

  • air enters through the body and travels down to the trachea, to the lungs
  • trachea split into two bronchi, which branches out into bronchioles
  • the air ends in little air sacs called alveoli - the exchange surface for gases in and out of the body
  • alveoli are highly adapted for efficient diffusion of O2 and CO2 in air and blood
• CIRCULATORY SYSTEM - the system of blood vessels that carry blood to the rest of the body

  • made up of the heart, blood vessels, blood

  DOUBLE CIRCULATORY SYSTEM

  • made up of two loops joined together
  • heart pumps deoxygenated blood to the lungs to become oxygenated, and returns to the heart
  • heart then pumpd oxygenated blood around the rest of the body to supply respiring cells, before returning when deoxygenated again
• THE HEART

  A) vena cava

  B) rigt atrium

  C) right ventricle

  D) pulmonary artery

  E) pulmonary vein

  F) left atrium

  G) left ventricle

  H) aorta

  
• what is a pacemaker?

  a group of cells in the right atrium wall controlling your resting heart rate
• coronary heart disease - when the coronary arteries get blocked by layers of fatty materials, restricting blood flow and oxygen reaching cells , causing a heart attack
• STENTS

  • tubes inserted into the arteries to hold tem open for blood to pass through
  • reduce risk of heart attacks, remain effective for a long time, recovery time from surgery is quite quick
  • risk of complications and infections during operation, and blood clots

  STATINS

  • a drug that reduces the amount of 'bad' cholersterol in blood
  • reduces risk of strokes, coronary heart disease, and headt attacks
  • thye must be taken regularly, risk of negative side effects e.g. headachs, joint pains etc., they don't take effect immediately
• FAULTY HEART VALVES

  • valves in the heart can be damaged
  • can be replaced by either biological valves (humans or animas), or mechanical valves (man-made)
  • major surgery which can cause blood clots

  ARTIFICIAL HEART

  • patients can have a heart transplant, which usually comes from deceased donors
  • high demand for transplants, very long waiting lists
  • parts of the artificial heart can wear out easily
  • blood clots - patients must take blood thinning drugs which can cause problems if they are accidently hurt
• communicable diseases - diseases that spread from human to human, or between animals and people

  • can be caused by things like bacteria, viruses, parasites, fungi

  non-communicable diseases - diseases that cannot be spread between people , or animals and people. there can be financial and human costs:

  • poor QoL, reduced lifespan
  • emotional impacts on family and friends
  • heathcare, treatments, research can be expensive
• STRUCTURE OF LEAF

  • upper epidermis - transparent and very thin to allow light to pass through palisade layer
  • lower epidermis - full of little holes called stomata. allows gases to diffuse in and out of cell
  • palisade tissue - near top of leaf and has lots of chloroplasts to absorb light
  • spongy mesophyll tissue - lots of air space so gases can diffuse in and out of cells
  • xylem and phloem tissues - supply leaf with water and nutrients, removes glucose
  • meristem tissue - found at tips of roots. contains plant stem cells, enables plants to create new cells for growth and repair
• guard cells control gas exchange and water loss from leaf by opening and closing stomata

  • when lots of water, guard cells become turgid (stomata opens)
  • when little water, guard cells become flaccid (stomata closes)

  guard cells are sensitive to light

  • in the day, they open to let CO2 enter leaf for photosynthesis
  • when dark, the close to prevent excess water loss
• blood vessels: arteries

  • carries blood away from the heart
  • blood is pumped at high pressure to transprt blood around the body
  • thick walls - thick layer of elastic fibres and smooth muscle
  • narrow lumen
• blood vessels: capillaries

  • involved in the exchange of materials at the tissues
  • tiny vessels
  • suppy cells with O2 and glucose for respiration, removes waste products
  • permeable walls and only one cell thick - provides a short distance for diffusion
  • permeable walls increase the rate of diffusion
  • very small lumen
• blood vessels: veins

  • takes blood back to the heart (e.g. vena cava, pulmonary vein)
  • blood is under low pressure - walls of veins are not as thick as arteries
  • large lumen - allows blood to flow despite low pressure
  • has valves to keep blood flowing in right direction
• disease risk factors

  • smoking, poor diet, lack of excercise - risk of cardiovascular disease
  • obesity - risk of diabetes type 2
  • large amounts of alcahol - risk of liver disease
  • exposure to carcinogens e.g. x-rays - risk of cancer
• CANCER

  • tumours are formed when cells divide uncontrollably. can either be benign or malignant
• benign tumours

  • usually stays in one place within a membrane in the body
  • do not invade other tissues
  • most often harmless
• malignant tumors

  • spread to other parts of the body
  • causes secondary tumours to form in different places
  • can be fatal
  • cancerous
• risk factors causing cancer

  • obesity
  • smoking
  • UV exposure
  • viral infections - can trigger the formation of cancer
  • some faulty genes can be inherited
• how to reduce risk of cancer

  • eating balancd diet
  • no smoking
  • limiting time in direct sunlight
  • excersising regularly

  cancer survival rates have increased due to extensive research, increased screening and development of treatment
• most transpiration happens in leaves:

  • water diffuses and evapourates into the atmosphere which creates a shprtage in leaf
  • water is drawn up in xylem cell from soil, into roots and into leaves to replace water
  • root hair cells from roots are adapted for efficient uptake of water by osmosis, and mineral ions by active transport

  water exits the leaf through pores called stomata
• transpiration rate

  • temperature
  • humidity
  • air movement
  • light intensity - in light, guard cells become turgid and opens stomata, which increases water loss
• red blood cells

  • carry oxygen from the lungs to cells around the body for aerobic respiration
  • bi-concave shape - increases surface area
  • no nucleas to make room for haemoglobin
  • small
• white blood cells

  • responsible for identifying and destroying pathogens
  • has a nucleus
  • two types: phagocytes (engulfs and digests pathogens) lymphocytes (identify pathogens and produce antibodies that binds to antigens on pathogens)
• platelets

  • fragments of cells produced in bone marrow that cause blood to clots
  • no nucleus
  • important when organism has a wound to stop blood flowing out of body and stop pathogens
  • they form blood clots and scabs
• plasma

  • pale yellow liquid that transports everything in the blood
  • in all other blood cells and platelets
• transpiration

  • the process of water movement through a plant