Biology aqa A level common questions

Biology aqa A level common questions a mutation can lead to the production of a non functional enzyme. explain how? (6) - × change in base sequence of DNA × change in AA sequence/ 1° structure of enzyme × change in h, ionic/ disulphide bonds × change in 3° structure × change in active site × substrate not complementary cannot bind to active site no e-s complexes A recessive allele which has harmful effects is able to reach a higher frequency in a population than a harmful dominant allele. Explain how ? - recessive allele can be carried by individuals showing effects dominant allel always expressed organisms that are affected are more likely to reproduce therefore recessive alleles are more likely to be passed on advantage of shrew having haemoglobin with a dissociation curve to the right explain? - at the tissues low p.p of o2 - haemoglobin is less reduced affinity more o2 released oxyhaemoglobin dissociated more readilt more o2 released allows greater respiration rate assumptions made when using the mark release method ? - no immigration no losses to predation marking does not affect survival