outline the vitamin c practical
- obtain at least 5 different vitamin c solutions with a known concentration
- use a PIPETTE to get the set volume of the DCPIP, then titrate it into each vitamin c solution recording when the solution turns from BLUE to COLOURLESS,
- then record the volume of DCPIP that was needed
- then repeat the experiment 3 times to then get an average volume for each solution
- plot a graph and then get the line of best fit.
outline the process of blood clotting
Blood clotting is described as a cascade of events. Platelets and damaged tissue release the enzyme thromboplastin. Thromboplastin converts prothrombin to thrombin. In addition to other clotting factors, calcium ions and vitamin K are also required. The thrombin converts soluble fibrinogen into insoluble fibrin. The fibrin forms a mesh of fibres which traps, platelets and red blood cells resulting in the formation of a blood clot.
Explain how blood clots can result in myocardial infarction (6 marks)
If a blood clot forms in the coronary artery this can prevent blood containing oxygen and glucose from reaching the cells below the blockage. This prevents aerobic respiration from occurring and anaerobic respiration occurs. Anaerobic respiration results in a build-up of lactic acid in the cells and therefore results in a reduced pH. The low pH denatures the enzymes in the heart cells and the heart cells begin to die. In addition, insufficient ATP is generated and the heart cells do not have sufficient energy to contract.
Explain how blood clots can result in a stroke (6 marks)
If a blood clot forms in an artery leading to the brain this can result in a stroke. The blood clot reduces the flow of oxygenated blood to the brain cells. This results in the brain cells receiving less oxygen and glucose. The brain cells are no longer able to carry out aerobic respiration and so they start respiring anaerobically. This results in less ATP being produced but also the build-up of lactic acid. The lactic acid decreases the pH and the enzymes start to denature and the cells begin to die, resulting in a stroke.
Describe the structure of glycogen (4 marks)
Glycogen is a polysaccharide. It is made up of many monosaccharides of α glucose joined by α1-4 glycosidic bonds formed through condensation reactions. Glycogen also contains α1-6 glycosidic bonds which makes it a highly branched structure.
Describe the structure of starch (6 marks)
Starch is composed of two polysaccharides; amylose and amylopectin. Both of which are made up of α glucose joined by glycosidic bonds formed through condensation reactions. Amylose contains α1-4 glycosidic bonds and is unbranched and coiled. However amylopectin contains both α1-4 glycosidic bonds and α1-6 glycosidic bonds making it a branched molecule.
Explain how the structure of glycogen is related to its function (5 marks)
Glycogen is a polysaccharide of α glucose joined by α1-4 glycosidic bonds, which means that it stores lots of glucose which is the respiratory substrate. Glycogen also contains α1-6 glycosidic bonds which means it is a branched molecule. The side branches can easily be hydrolysed by enzymes should glucose be required for respiration. Glycogen is also a coiled, compact molecule which means that large quantities can be stored in small spaces such as muscle cells. It is also insoluble so it therefore does not affect the osmotic balance of the cell.
Compare and contrast amylose and amylopectin (5 marks)
Both amylose and amylopectin contain α glucose joined by α1-4 glycosidic bonds formed through condensation reactions. They are therefore both polysaccharides of glucose. Amylopectin however also contains α1-6 glycosidic bonds resulting in side branches. Amylose does not contain α1-6 glycosidic bonds and is therefore unbranched.
explain the structure of starch in relation to the function
plants store their excess glucose as starch, so that when it is broken down it releases glucose. starch is a mixture of two polysaccharides, amylose and amylopectin. amylose has a 1,4 glycosidic bond, and is unbranched, and is coiled, this allows it to be easily compact. amylopectin has both 1,4 and 1,6 glycosidic bond, making it branched and therefore can be easily hydrolysed and release glucose for the plant. and it is insoluble so does not affect the osmotic potential.
daphnia practical
- get a range of caffeine solution at least 5 with a control (the pond water of the daphnia)
- get cotton fibres and place on the slide (to prevent movement because this can affect the heart rate)
then get a daphnia ( making sure that all the daphnia used for each test come from the same pond and roughly the same size) - then place the daphnia on the cotton and then using a PIPETTE but a few drops of the daphnia solution, then set a time of 3 minutes so the daphnia can become accustomed to the new environment.
-then from looking at the microscope locate the heart and then count each heart beat of the daphnia for 15 seconds, then multiple the value by 4 to get the BPM - the repeat this 3 times with different daphnia to get an average
- then repeat for each different concentration and then compare the results
Outline the process of atherosclerosis (6 marks)
Atherosclerosis is a self-perpetuating process. High blood pressure results in damage to the endothelium of the artery. This results in an inflammatory response and white blood cells called macrophages migrate to the damaged area. The macrophages engulf cholesterol and become foam cells. The foam cells burst, releasing the cholesterol. The cholesterol, calcium ions and fibrous tissue harden to form an atheroma/plaque. This results in the narrowing of the lumen and a loss of elasticity in the walls of the artery.
factors that can affect the risk of cardiovascular disease
- diet = a diet high in saturated fat will increase the blood cholesterol levels increasing the chance of an atheroma forming, which can lead to a blood clot which can also lead to stroke or heart attack.
- high blood pressure = increases the risk to the artery wall increasing the risk of an atheroma forming.
- smoking = carbon monoxide combines with the haemoglobin, reducing the amount of oxygen, which will reduce the oxygen for the tissues, which may lead to heart attack or stoke
=nicotine makes platelets more sticky so blood clots are more likely to form.
gender = men are more likely to suffer from cardiovascular diseases age = more likely to develop CVD at older ages
treatments for CVD
- antihypertensives (to reduce blood pressure) = BETA BLOCKERS (reduces the strength of the heart beat)and VASODILATORS (widens the blood vessels)
- STATINS ( to reduce cholesterol) = reduce the amount of LDL made in the liver.
- ANTICOAGULANTS- reduces the chances of clood clots forming
