(Original post by TheRabbit)
1.a)i)Active transport is the process by which substances are moved in or out of the cell against a concentration gradient.
ii) Mitichondria for energy
iii) Microvilli for increased cell surface area
b) Transmembrane proteins
c)i) X is the matrix and is where the Kreb cycle occurs
Y is the cristae and is where electron transfer or terminal respiration occurs
ii) fewer folds in the wall as less ATP needs to be generated and the ATP is generated by electron transfer at the cristae
b) i) B cell/lymphocyte
ii) I think it means recognise foreign antigen and mobilise cell response?
c) If there is reinfection memory cells can produce the antibody fast and in large quantities
d) Different viruses have different structures to their components, which are antigens, so an antibody which is able to interact with one virus can’t with another.
ii) Allows a patient to be protected if their own immune system cannot mount enough of a immune reaction to deal with an infection; however the patient has no lasting immunity if there is reinfection
3. a) R Dd and S D (technically XDXd, XDY
iii) Son of T 0%, son of U 50%
ii) It may be missing a base or section, have an extra base or section or have a different order from normal
iii) Dystrophin is a protein made up of amino acids coded for in a particular order by the DNA bases in the gene if the gene is changed then the amino acids are in the wrong order or number so produced a different structure that will not work in the same way.
4.a)i) Trypsin breaks down the protein which is holding the colour to the films so the black is removed leaving a clear film
ii) temperature, size and type of photographic film, volume of trypsin solution
iii)repeat the experiment
v) There were more enzyme molecules available to break down the protein
vi) The maximum amount of substrate was being broken down at once – there was no more substrate for the extra enzyme to breakdown
ii) Otherwise they would breakdown the cell that produces them
iii) cofactors or modulators
5.a)i) X is the sino-atrial node or SAN, Y is the atrio-ventricular node, AVN
ii) Atrial contraction
iii) Down the middle bit and up the sides
b)i) mitral or bicuspid
10. a) 51 wks
b) all but 7
c) 1. Normal variation
2. Developmental abnormality
d)i) Maturation (I think)
ii) Myelination of the motor nerves to the muscles of the lower limbs
11. a) Randomisation of individuals to groups, going for 2 groups of similar individuals (age, gender, occupation)
b) Something to do with short term memory
c) To fill up short term memory so that the test words would be pushed out and longterm memory was tested
d) People remember fewer words correctly after a period of an hour and people are more likely to correctly remember related words after an hour (than unrelated words)
12. a)i) Birth rate is falling and an increasingly sharp rate during stage 2 and then flattens out to a fairly constant level in stage 3
ii) At the start of stage 2 death rates are falling more rapidly than birth rate so population is gwoing, this growth increases as the gap between the rate in fall of death rate increases compared to the rate of fall in birth rates. As we come to the end of stage 2 the gap between birth and death rates narrows as death rates decrease at a slower rate and birth rate decreases at a higher rate so that they are both at roughly the same number of people going into stage 3.
iii) Improved healthcare due to knowledge and technology, more food available and better diet, cleaner water
b)i) Pesticides can skew the food web by removing one organism from the web allowing the amount of its prey or food to rise and providing more food for any organism which shares the pesticide killed organisms food. SO you either get excess of the food/prey or excess of another organism which normally competes with it for food. [yeah I’m tired hence poor explanantion!]
ii) Crop rotation, monoculture?
c)i) A sudden rise in algal population in an aquatic environment
ii) The bloom may block the light from reaching below it, meaning other aquatic plants die (so less O2 from photosynthesis), and the algae doesn’t survive very long and with the other plants starts to rot and decay which uses up the O2. The O2 in the water decreases killing fish and other lifeforms.