topic 2 - organisation

• what is a group of organs working together to perform a particular function called?

  Organ system
• true or false, a tissue is a group of cells of only one type, which work together to perform a function?

  false, a tissue doesn't have to be made up of only one cell type, it can include more than 1 type of cell
• what is an organ?

  A group of different tissues that work together to perform a specific function in the body.
• what is the role of the digestive system?

  the digestive system breaks down and absorbs food
• how do enzymes affect the rate of reaction?

  enzymes increase the rate of a reaction (they act as a biological catalyst)
• what is an active site of an enzyme?

  the active site is the part of the enzyme that the substrate fits into
• give two variables that affect the rate of an enzyme controlled reaction?

  temperature and pH
• what is the "lock and key" model of enzyme action?

  the "lock and key" model is a simplified model of enzyme action. It states that a reaction will only be catalysed if the shape of the substrate exactly matches the shape of the enzymes active site, so that the substrate fits directly into the active site.
• which type of molecule is broke down into amino acids?

  proteins
• what are the products of lipid digestion?

  Fatty acids and glycerol.
• in which organs are proteases produced?

  Pancreas, stomach, small intestine
• which organ produces bile and where is it stored?

  the liver produces bile and it is stored in the gall bladder
• what does the body use the products of digestion for?

  the products of digestion can be used to build new carbohydrates, proteins and lipids and some of the glucose produced is used in respiration.
• give two functions of bile and explain how these aid digestion?

  1. Emulsification 2. Neutralization Bile emulsifies fats into smaller droplets, increasing the surface area for enzymes to work on. Bile also neutralizes stomach acid, creating a more optimal pH for enzyme activity in the small intestine.
• describe how to test a sample of food for protein, starch and sugar give the colour of a positive result?

  Protein -> Biuret test -> Purple Starch -> Iodine -> Blue Sugar -> Benedict's + Boil -> Red
• name the structures in the lungs where gas exchange takes place?

  Alveoli
• explain how gas is exchanged between the lungs and blood that has just returned from the rest of the body?

  the alveoli are surrounded by a network of blood capillaries. Blood that has just returned from the rest of the body has a low oxygen concentration and a high carbon dioxide concentration. In alveoli the oxygen concentration is high and the carbon dioxide concentration is low. This means oxygen diffuses out of the alveoli into the blood, and carbon dioxide diffuses out of the blood into the alveoli
• when blood reaches body cells, gases are exchanged between them. Explain how gases move between blood and body cells?

  Oxygen is released from the red blood cells, where the oxygen concentration is high, and diffuses into the body cells where the concentration is low. Carbon dioxide diffuses out of the body cells and into the blood, down the concentration gradient
• which side of the heart pumps deoxygenated blood into the lungs?

  Right
• name the blood vessel which carries blood into the right atrium of the heart?

  vena cava
• what is the function of valves in the heart?

  Prevent backflow.
• describe the route that the blood from the lungs takes to the heart?

  oxygenated blood from the lungs enters the left atrium through the pulmonary vein. It is then pushed into the left ventricle, and then leaves the heart via the aorta.
• what is the function of white blood cells?

  white blood cells defend the body against infection
• what is plasma?

  plasma is the liquid that carries everything in blood
• what are the three adaptations of exchange surfaces?

  1 cell thick -> short diffusion distance, good blood supply ->maintains a steep concentration gradient, many ...... -> large surface area
• describe the difference in thickness between an artery wall and a vein wall. why does this difference exist?

  arteries have thicker walls than veins. Arteries carry blood that has been pumped from the heart at high pressure, so the walls have thick layers of muscle and elastic fibres to make them strong and elastic. In veins blood is at low pressure, so the walls don't need to be as thick.
• how are red blood cells adapted to their function?

  Red blood cells have a biconcave shape, which gives them a large surface area for absorbing oxygen. They have no nucleus, which allows more room to carry oxygen. Oxygen binds to haemoglobin in the cells when the blood flows through the lungs.
• what is a stent? how do stents reduce the risk of heart attacks?

  a stent is a tube that is inserted inside an artery. Stents keep coronary arteries open, so oxygenated blood can flow into the heart muscle.
• what is one disadvantage of using stents?

  there is a risk of complications during the operation, a risk of infection from surgery, and a risk of patients developing thrombosis near the stent
• how might statins help to treat coronary heart disease?

  reduce cholesterol in the blood, slowing down the rate of fatty deposit formation
• true or false, communicable diseases can be spread between people, or between animals and people?

  True
• give three examples of non-communicable diseases?

  asthma, cancer and coronary heart disease
• HIV is a virus that causes damage to the immune system. How would having HIV affect the likelihood of a person contracting a communicable disease, such as tuberculosis?

  HIV would make a person more likely to contract communicable diseases because their body is less able to defend itself against pathogens.
• give two factors other than disease and life situation that can affect a persons health?

  diet and stress
• what is meant by the term carcinogen?

  Cancer-causing substance.
• name two organs that are affected by drinking too much alcohol?

  Liver, Brain
• suggest two unhealthy habits that a woman should avoid while she is pregnant to protect the health of her unborn baby?

  Smoking, alcohol consumption
• what is a tumour? what causes tumours to form?

  a tumour is a mass of cells. Tumours are formed as a result of cellular changes which lead to uncontrolled cell growth and division.
• true of false, benign tumours are not cancerous?

  True, only malignant tumours are cancerous.
• what are secondary tumours, and how do they form?

  secondary tumours are tumours that form when malignant tumour cells break off the original tumour and spread to other parts of the body via the blood to form a new tumour.