Exam questions Flashcards
describe how the atrioventricular ventricular valves work during one cardiac cycle
(2)
- valves are open to allow blood to flow from the atria to the ventricles/open during atrial systole/when atria contract
- valves close when ventricles contract/ventricular systole
- valves prevent backflow of blood into the atria during ventricular systole
explain why the semilunar valves close (2)
- the pressure in the aorta is higher than the pressure in the left ventricle during diastole
- therefore forcing blood around the body rather than flowing back into the ventricle
explain why the mammalian heart is divided into a right and left side (2)
- keeps deoxygenated and oxygenated blood separate
- separation results in as much oxygen as possible being carried to the {tissues/cells}
- blood needs to be pumped at different pressure (lower pressure to the lung + higher pressure to the body)
describe the structure of the mammalian heart (5)
- four chambers
- 2 atria on top 2 ventricles below
- left and right separated by a septum
- reference to cardiac muscle
- thickness of the ventricles walls
- position of atrioventricular valves
- position of semilunar valves
- position of the aorta/pulmonary artery
- position of vena cava/pulmonary vein
- reference of coronary arteries
explain the difference in thickness of the wall of the right atrium and the wall of the right ventricle (3)
- right atrium has less muscle
- reference to the thickness of the walls being related to pressure
- right atrium pumps blood to right ventricle
- right ventricle pumps blood to the lungs
in mammals, blood passes through the heart twice for each circulation of the body.
suggest how this type of circulation enables mammals to carry out effective gas exchange (3)
- right side of the heart pumps blood to the lungs and the left side of the heart pumps blood to the body
- separation of oxygenated and deoxygenated blood
- idea of maintaining gas {concentration/diffusion} gradient
- lower pressure in right side of the heart protects delicate structures e.g. capillary or alveoli
- high pressure allows for {rapid} {mass flow/supply of oxygen} to body cells
describe the role of the heart valves in the cardiac cycle (6)
- atria contact/atrial systole
- av valves open so blood flows from atria to ventricles
- ventricles contract/ventricular systole
- av valves close to prevent backflow of blood into the atria
- sl valves open so blood {leaves the ventricles/enters pulmonary artery/aorta}
- ventricles relax/ventricular diastole
- sl valves close
- to prevent the backflow of blood into the ventricles from aorta/pulmonary arteries
explain the function of the elastic fibres in the aorta (2)
- allow stretch and recoil
- in order to maintain blood pressure
explain how the structure of an artery wall is adapted both to withstand and to maintain high blood pressure (3)
- more collagen provides strength to withstand pressure
- contraction of muscles allow narrowing of the {artery/lumen}
- elastic fibres allow stretch and {recoil/lumen returning to original size}
explain why blood clot formation in capillaries could cause tissues to die (2)
- lumen of capillaries is blocked
- preventing the supply of {oxygen/glucose} to tissues/cells
- stopping respiration/anaerobic respiration causes a build up of lactic acid
explain how the structure of a vein relates to its function (4)
- valves prevent backflow of blood
- smooth endothelium to reduce resistance to blood flow
- large lumen to reduce resistance of blood flow back to the heart
- thin walls to maintain lower blood pressure
compare and contrast the structure of the aorta with the structure of the pulmonary artery (2)
similarities:
- both have walls containing {elastic fibres/muscle cells/collagen layer}
- both have a valve
differences:
- aorta has a {wider lumen/thicker walls/more collagen/ more muscle tissue}
-aorta has branches to more organs
explain how arteries are adapted to accommodate sudden increases in blood flow (2)
- elastic fibres can {stretch/expand}
- therefore {widening the lumen} of the artery
- walls contain collagen to increase the strength
explain how arteries are adapted to reduce resistance to blood flow (2)
- inside of artery is lined with the smooth endothelium
- to reduce friction
explain why the total surface area of the capillaries needs to be so high (2)
- more plasma is able to leave the capillaries
- results in faster diffusion
- more capillaries are in contact with the cells (short diffusion distance)
describe how tissue fluid is formed (2)
- hydrostatic pressure generated by the heart
- water and low molecular mass solutes forced out of capillaries
describe how the structure of the aorta is related to its function (4)
- wall of the aorta is {thick/contains collagen}
- to withstand pressure
- wall of the aorta contains {elastic fibres}
- allowing the wall of the aorta to stretch and recoil
- valves present at the start of the aorta
- prevents backflow of blood during diastole
explain why many animals need a heart and a circulatory system (4)
- heart is needed to pump blood around the body
- reference to mass flow
- animals have a small surface area to volume ratio
- circulatory system is needed to overcome the limitations of diffusion
- transport of a named molecule in the blood
- idea that mammals have a high metabolic rate
explain how the properties of water molecules result in surface tension (3)
- water molecules are polar
- therefore form hydrogen bonds
- therefore are cohesive
- which result in an inward force at its surface
explain how the dipolar nature of water is essential for living organisms (2)
- water can form hydrogen bonds
- water is a solvent so polar molecule can {dissolve/be transported} in water
- hydrogen bonds holds water molecules together as a liquid so it can move in a mass flow system
describe how very high blood pressure could result in atherosclerosis (3)
- high blood pressure damages the endothelium of the artery
- cases an inflammatory response
- {white blood cells/cholesterol} accumulates/atheroma forms
- calcium salts/fibrous tissue builds up/formation of plaque
explain how atherosclerosis in one part of an artery could increase the likelihood of it developing in another part of the same artery (2)
- {plaque/atherosclerosis} narrows the lumen of the artery
- increasing blood pressure more
explain why a stent is used in the treatment of atherosclerosis in a coronary artery (3)
- to widen the lumen of the coronary artery
- so that more blood can flow to the heart {cells/muscle}
- for respiration in the heart muscle
explain how atherosclerosis can result in damage to the heart muscle (4)
- formation of blood clot/thickening of the artery walls
- therefore {blocks/narrows} the coronary arteries
- reduces blood flow
- depriving the heart muscle of {oxygen/nutrients}
explain how an increase in dietary salt can lead to the development of atherosclerosis (5)
- high salt causes an increase in blood volume
- causing high blood pressure which damages the endothelium in arteries
- this causes an inflammatory response
- cholesterol deposits lead to atheroma/calcium deposits lead to formation of plaque
- therefore arteries {narrow/loose elasticity/ harden}
describe how atherosclerosis develops (4)
- damage to endothelium of the artery
- inflammatory response
- white blood cells gather in the area
- build up of cholesterol
- formation of atheroma/plaque
- reference to calcium salts/fibrous tissues
- loss of elasticity/ narrowing of lumen of artery
- self perpetuating process
explain why raised lipid levels in the blood may increase the risk of developing CVD
(4)
- increased risk of {cholesterol deposits/higher blood cholesterol}
- leads to formation of {atheroma/plaque/atherosclerosis}
- increased risk of blood clot forming
- loss of elasticity to artery/lumen narrowing
- increasing blood pressure
explain the role of blood clots in heart disease (3)
- blood clots can block coronary arteries
- reducing the {flow of blood/supply of oxygen} to the heart tissues
- resulting in heart attack
describe the role of thrombin in blood clotting (3)
- thrombin is an enzyme
- catalyses the conversion of fibrinogen into fibrin
- fibrin mesh traps {platelets/red blood cells} to form a clot
describe the role of prothrombin in the blood clotting process (3)
- to be present in the blood at all times
- needed to make thrombin
- which is an {enzyme/catalyst}
- so fibrinogen can be converted into fibrin
explain why a blood clot in an artery leading to the brain could cause a stroke (3)
- reduced blood flow
- less {oxygen/glucose} reaches the brain
- less/no aerobic respiration
- less/no ATP produced
- brain needs lots of ATP/energy to function
- lactic acid produced from anaerobic respiration
- lactic acid inhibits enzymes/is toxic
describe the blood clotting process (4)
- idea of cascade of events leading to clot
- thromboplastin starting the cascade
- conversion of prothrombin into thrombin
- thromboplastin/thrombin is an enzyme/catalyst
- conversion of fibrinogen to fibrin by thrombin
- requirement of calcium ions/vitamin K
- platelets getting trapped in mesh
devise a procedure to compare the effects of caffeine concentration of the heartbeat of daphnia (4)
- daphnia immobilised on a cavity slide
- range of different caffeine concentrations (0, 0.1, 0.5)
- acclimatisation/using a microscope/method of counting
- record heartbeat before (in water) then after (in caffeine solution)
- controlled variable for the caffeine (concentration/volume)
- controlled variables (temperature/length of count time/same species/age)
- repeats carried out and calculate mean
explain how the structure of glycogen allows it to be an energy store (3)
- polymer of glucose
- to provide glucose for respiration
- {branched/contains 1,6 glycosidic bonds/has many terminal ends} for rapid hydrolysis
- compact to allow large amounts of glucose/energy to be stored in a small space
describe the structure of starch (3)
- polysaccharide made of alpha glucose units
- units in the chain are joined by 1,4 glycosidic bonds
- contains unbranched molecule/amylose and branched chain/amylopectin
- branches are joined to chains by 1,6 glycosidic bonds
compare and contrast the structure of amylose with the structure of amylopectin (3)
similarities:
- both polymers of alpha glucose
- both contain 1,4 glycosidic bonds
differences:
- amylose has 1,4 glycosidic bonds only whereas amylopectin has 1,4 and 1,6 glycosidic bonds
- amylose is an unbranched molecule and amylopectin is a branched molecule
compare and contrast the structure of glucose with the structure of glycogen (3)
similarities:
- both contain alpha glucose
- both contain C,O and H only
differences:
- glucose is a monosaccharide whereas glycogen is a polysaccharide
- glycogen has 1,4 and 1,6 glycosidic bonds whereas glucose does not have glycosidic bonds
describe the structure of a triglyceride (2)
- one glycerol and three fatty acids
- joined by ester bonds/esterification
state two differences between the structure of a saturated lipid and an unsaturated lipid (2)
- saturated lipids have no carbon to carbon double bonds whereas unsaturated lipids have carbon to carbon double bonds
- saturated carbons have straight chains and unsaturated have kinks in their chains
describe an experiment that could be carried out to make a valid comparison of the vitamin C content of three fruits (6)
- obtain the juice from the three fruits
- controlled variable - age of fruit, volume of DCPIP, ripeness
- reference of DCPIP
- description of titration
- colour change from blue - colourless (when juice is added to DCPIP)
- record volume needed for colour change
- ref to standard deviation/calibration curve to determine vitamin C concentration
- repeat experiment and calculate mean
explain the role of antihypertensive drugs in reducing the risk of atherosclerosis (4)
- antihypertensive drugs lower blood pressure
- lower bp reduces the risk of damage to the endothelium of an artery
- reduced risk of inflammatory response
- reduced risk of {atheroma/plaque} formation
state three possible side effects of taking drugs to reduce blood pressure (3)
- nausea
- dizziness
- muscle cramps
- kidney failure
explain why antioxidants in the diet reduce the risk of CVD (3)
- antioxidants reduce free radicals
- therefore {cell damage/damage to lining of blood vessels} is reduced
- reducing {plaque/atheroma} formation
explain the benefits of warfarin in the treatment of CVD (3)
- prevents formation of a blood clot/thrombus
- reduces effectiveness of platelets (reduces stickiness)
- less chance of artery blockage
- maintains oxygen supply to tissues
- less risk of a heart attack/stroke
explain why patients with CVD would take each of the following drugs
platelet inhibitory drugs such as aspirin (2)
Antihypertensives such as beta-blockers (2)
platelet inhibitory drugs - aspirin
- prevents platelets becoming sticky/activated
- prevents formation of blood clot/thrombus
-reducing risk of stroke
antihypertensives - beta-blockers
- reduces blood pressure
- reduces heart rate
- prevents muscles in vessel walls contracting
explain how anticoagulants can help reduce the effects of CVD (2)
- prevents the formation of a blood clot/thrombus
- reduces stickiness of platelets
- clotting factor is not synthesised/inhibited (fibrinogen/thromboplastin/prothrombin)
- risk of blood vessels becoming blocked is reduced
explain why statins reduce the risk of CVD (2)
- inhibit the synthesis/production of cholesterol of cholesterol in the liver
- reducing blood cholesterol levels
- raises HDL levels/increases HDL:LDL levels/lowers LDL levels
