PAPER 2 2020 -

c 1/1

b 0/1

from the data i can conclude that colchine has little to no effect on the amount of cells that are in the interphase, as the values are similar with similar ranges. however i can then see that more cells in the colchine culture entered the prophase than the non colchine culture. this means that there nucleus breaks down and the chromosomes are able to condense successfully, however then the number of cells entering the meta phase anaphase and telophase are all lower in the colchine culture, they also all have lower ranges which increases the reliability, so it would suggest colchine stops chromosomes matching up on the metaphase plate, being pulled apart by the spindles and stops cytokinesis 2/4

an action potential travels down a presynaptic membrane, this stimulates the movement of acetylcholine containing vesicles to the surface of the neurones membrane, the vesicles then fuse to the membrane allowing the acetylcholine to diffuse through the synaptic cleft where it will bind to the receptors on the post synaptic 3/4

DFP will bind to the r group of the amino acids that makes up the receptor will change there conformation, therefore the active site will change shape, this means that the substrate will no longer fit specifically to the active site and so no enzyme - substrate complexes will be made and the impulse will not move past the synapse as the firing threshold wont be reached as suggested by the all or non law 2/2

if the activity of acetylcholinesterase is inhibited by DFP because of a change in the active site, then acetylcholine cannot be broken down, this means that there will be a build up acetylcholine in the synapse, therefore causing the effects of acetylcholine to occur due to the increased levels, an example of this is a slowed heart rate 1/1

the proximal convoluted tubule (PCT) cell has a large number of microvilli on its surface, this increases the surface area for selective reabsorption to occur on meaning the diffusion of useful molecules out of the filtrate is more efficient. the PCT cell also has a large number of mitochondria, this allows the cell to resynthesise a large amount of ATP to be used in selective reabsorption as its active, for example for the active reabsorption of sodium ions. the PCT cell also has a endoplasmic reticulum, this is used in protein synthesis which is vital for the cell to carry out, it also has a nucleus and nucleolus which carries the cells genetic material 4/4

b 1/1

c 1/1

once piece of evidence which supports the suggestion is that cats 1 and 2 where able to have both long and short haired offspring, this shows that if the short fur allele is inherited then that cat will definatly have short hair, for exmaple cats 4 and 5, where as if two copies of the long hair allele is inherited they will have long hair which supports the idea that the long hair allele is recessive and the short hair allele is dominant and those cats only needed to inherit one of the alleles to have short fur as the male cat 1 was homozygous for long hair, but could still have short hair offspring

XbY Ss XbY SS 1/1

in the case of these cats the allele for fur colour in carried on the x chromosome that means its sex linked, as male cats only inherit one x chromosome, they can only inherit either a black or orange allele for fur colour, whereas female cats inherit two x chromosomes so can inherit black and orange, meaning they will be tortoiseshell as ornage and black are codominant to each other in terms of fur colour 2/2

cocoa butter has a higher concentration of saturated fatty acids, this means that it has a higher meltimng point, so the % SFC is higher than palm oil which has a higher concentration of unsaturated fatty acids so has a lower %SFC than coccoa butter and a lower melting point. from the graph we can see that both palm oil and cocoa butters %SFC decreases as tempurature increases, but this happens at a faster rate for cocoa butter after 25 degrees escpecially. at 35 degrees both cocoa butter and palm oil have the dame %SFC of about 7 %

due to deforestation, the populations of orangutangs have become more spread out across borneo, in the places with low populations, the selction pressure is the same for all the orangutangs that live their meaning there will be a smaller gene pool and allele variation, this means that as the mating population is small inbreeding probably occurs, meaning any mutations causing deformaties and health problems will be passed on to more offspring as it will be liely that both parents carry the allele for it

if the payments happen, then palm oil will be able to be harvested from a larger area, so more can be collected, but having the land bridges will help orangutang populations become less isolated, this means that the gene pool of the species will increase again, as well as the number of mating partners whivh will increase genetic variation and make health problems and deformaties less common

CITES puts limits on the trade of endangered fauna and flora, this will decrease the often illegal sale of orangutangs and commodity products made from them , for example using their fur, but also will limit the harvesting of palm oil if it is seroisly endangering the speices by removing their habitats