(Original post by The Assassin)
Hey everyone. Hope you did well on your tests.
As I haven't seen one being made, I've made a start to one and will add more answers when more people contribute to it. This is obviously unofficial, so the real mark scheme could be pretty different. a ; denotes a different point for each mark.
a) Golgi Appartus (1 mark)
b) Nucleus or Nuclear envelope or Nucleolus; lysomomes; Mitochondria;ER
(2 points for 2 marks)
c) What's the function of the mitochondria?
Produce ATP (for energy)
d) Resolution is highest/greatest; due to shorter wavelength of electrons; can see detailed structures; amoeba are thin so TEM works (2 marks)
Describe investigation A
a) 2 drinks decrease the risk of heart disease; then increase it (as you drink more) (2 marks)
b) Why does the 40-50 age group improve the investigation?
Increases reliability because alcohol affects different age groups in different ways (metabolism, etc). (1 mark)
c) Evaluate the claim 'Alcohol is good for you'
Yes - in low consumption;
No - correlation does not mean causation;
may be another factor involved;
drinking more than 2/3 increases the risk of heart disease;
didn't specify what alcohols were so can't be sure on the quantity;
a) Describe what causes the diaphragm to change shape
(lungs changed shape) diaphragm contracts and flattens;
b) During these two phases, air moves into the lungs. Describe how the diaphragm allows this.
Diaphagm causes inspiration by contracting;
reducing pressure in the lungs;
air pressure outside greater causing it to flow into the lungs;
c) Diffusion through concentration graident; (2 marks)
through thin endothelium of alveoli;
then through thin endothelium of capillary wall;
a) What is a pathogen?
A micro-organism that causes disease. (1 mark)
b) Phagocytes may destroy bacteria. Explain how.
Phagocytes attracted by chemicals/recognise the antigens;
Remain in vacuole/vesicles/phagosome;
Lyosomoes release (hydrolytic) enzymes/fused with vacuoles;
Pathogen digested/hydrolysed/broken down;
c) Why does the antibody only target the specific antigen?
Specific primary structure/amino acid sequence;
Specific tertiary structure;
Determines binding sites;
Complementary to specific antigens;
a) Describe what the graph shows.
Slows it down up to (a certain point); then, sodium uptake is halted completely; (2 marks)
b) 0.2. The y-axis said concentration remaining, so you had to do 10 - 4 which is 6. Then divide that by 30 to get 0.2
c) Cyanide affects respiration. How did the cyanide affect the sodium uptake?
(Controversial too - I looked it up on Wikipedia and apparently it binds to cytochrome c in the mitochondria) (2? marks)
Acts as a competitive inhibitor;
Prevents mitochondria producing ATP for energy;
Energy needed in active transport/sodium-potassium pump/co-transport;
To remove sodium and maintain low concentration;
Less respiration happening;
Therefore glucose not being used up as quickly;
Therefore rate of uptake of glucose slower;
Glucose moves into cell by co-transport with sodium ions;
Therefore slower rate of glucose absorption means a slower rate of sodium ion absorption.
a) Describe the test for reducing sugars
with Benedicts reagent/solution;
Brick red precipitate will form;
b) Why did solution B contain more than Solution A?
Quite controversial. (3 marks)
enzyme breaks down starch into amylose;
reducing water potential in tube;
water moves in via osmosis;
c) The student said that a pH of 8 was the optimum temperature. Is this right?
Didn't test intermediate values (2-8);
Didn't test values above 8;
a) Hydrolysis (1 mark)
b) Proteins too large; carrier proteins are specific; carrier proteins may be damaged;
The proteins in membrane are selective; The conc of amino acids in cell is greater than conc of amino acids outside cell; facilitated diffusion involves that involves movement of
large molecules DOWN a conc gradient. Hence why the dipeptide cannot diffuse through. (3 marks)
c) Villi become damaged; reduced surface area; less diffusion;
membrane bound enzymes; reduced breakdown of proteins; less absorption (Once only for less absorption) (3 marks)
d) Why does the gluten stimulate an immune response?
(Some lines from the text) + sees it as non-self (1 mark)
e) Factors to consider: Side effects; Cost; Injection/Oral; Overall effectiveness (2 marks)
a) How does the heart co-ordinate contraction of the atria and ventricles?
SAN sends out electrical activity/wave of impulses;
Stimulates contraction of atria/initiates heart beat/acts as pacemaker;
AVN delays (electrical impulses);
Allowing atria to fill before ventricles contract/ventricles to fill before
AVN sends of wave of electrical activity down Bundle of His/Purkyne fibres;
Causing ventricles to contract (from base up) / ventricular systole;
b) How does a diet increase the risk of heart disease?
High consumption of fat/cholestrol accumulate in artery wall/ under lining / endothelium of artery;
Can cause blood clots/thrombus
May break off;
and get lodged in the coronary artery;
Reduces blood supply;
(so) reduces oxygen supply;
Heart muscle can't respire without oxygen and so dies;
can causes high blood pressures;
Why are people negging :L mad because you got things totally different to this?