Exam Questions Flashcards
Describe how an enzyme, such as pepsin, breaks down a substrate (5 marks)
- The substrate is complementary to the active site of the enzyme
- The substrate fits into the active site of the enzyme (induced fit hypothesis)
- Forms an enzyme-substrate complex where the bonds of the substrate are weakened (destabilised)
- Enzyme product complex is formed
- Products leave the active site (amino acids)
How do you increase the validity of the results?
- improve measurement techniques (more precise)
- make the experiment equal avoid bias
How does repeating and investigation improve it?
- Improves the reliability
- Allows for the calculation of means
- asses the spread of the results
Explain the process of how the heart pumps blood
- Both atria fill with blood
- Both atria contract simultaneously
- Atrioventricular valves of both sides open
- Both ventricles fill with blood from the atria
- Both Ventricles contract simultaneously
- Atrioventricular valves close
- Semilunar valves open
- Right ventricle pumps the deoxygenated blood to the lungs through the pulmonary artery
- Left ventricle pumps oxygenated blood through the aorta to the rest of the body
- Both ventricles relax (refractory period)
- Semilunar valves close
- Both atria begin to fill with blood
How is an impulse generated and propagated through the heart?
- SAN generates an electrical impulse
- the wave of contraction spreads to both atria
- causing them to contract
- the layer of non conducting tissue prevents the wave of contraction from reaching the ventricles
- The electrical impulse reaches the AVN and is delayed
- The electrical impulse is relayed to the bundle of His
- The impulse is then conveyed through the two bundle branches to the Purkinje fibres
- This causes both ventricles to contract starting at the apex for more efficient pumping of the blood
Explain the process of how RBCs carry CO2
- 10-20% binds to haemoglobin to form CARBAMINOHAEMAGLOBIN
- carbonic anhydrase catalyses the reaction between CO2 and H2O to form carbonic acid (H2CO3)
- hydrogen ion dissociates from the carbonic acid and forms H+ and HCO3-
- H+ ions are removed by buffers
- HCO3- move out of the erythrocyte into the plasma down a concentration gradient
- Chloride shift occurs to maintain the electrical balance of the cell
How is tissue fluid (interstitial fluid) drained lymphatically and reabsorbed back into the capillaries? refer to oncotic and blood pressure.
- as the blood moves along the capillaries the HYDROSTATIC PRESSURE falls and the ONCOTIC pressure is now stronger than the hydrostatic pressure
- so water moves back into the capillaries by OSMOSIS
- 90% of tissue fluid is drained back into the veins
- 10% is drained into the lymphatic system
How is tissue fluid (interstitial fluid) formed? refer to oncotic and blood pressure.
- as blood flows into the capillaries from the arterioles it is under high HYDROSTATIC PRESSURE
- This is greater than the oncotic pressure (due to the plasma proteins still in the capillaries) (-3.3kpa) so the blood plasma is forced out into the interstitial spaces of the surrounding tissue
- at this point, it becomes tissue fluid (interstitial fluid)
- It is blood plasma without erythrocytes and plasma proteins
- diffusion takes place here
Evaluate
Pros and Cons
-Evaluate the techniques used to measure and comment on how that can affect the results
Advantage and disadvantage of keeping habituated animals (2 marks)
+Natural behaviour
+Less likely to catch a disease from humans
-Poaching more likely
-difficult to count
Sources of natural medicine (2 marks)
- Plants
- microorganisms
the function of a disulfide bond in antibodies (2)
-to hold the heavy and light polypeptide chain together
What supports hydrophytes stem? (2 marks)
- Water surface
- Air spaces (parenchyma)
Limitations to methods (2 marks)
- Size
- Shape
- Volume
- Time
- Technique
Why does facilitated diffusion require no ATP energy?
- Particles have their own kinetic energy
- Moves down a CONCENTRATION GRADIENT
