AQA AS BIOLOGY 7401/2 PAPER 2 LATEST WITH QUESTIONS AND CORRECT ANSWER

AQA AS BIOLOGY 7401/2 PAPER 2 LATEST WITH QUESTIONS AND CORRECT ANSWER Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide. Give two reasons why. - ANSWER degenerate code could happen in introns/non coding Suggest a method that could be used to measure the quantity of reducing sugar in a solution. - ANSWER Filter and dry the precipitate Weigh/find mass Why using a colorimeter improves the repeatability of the student's results. - ANSWER quantitative colour change is subjective standardises values Explain how the active site of an enzyme causes a high rate of reaction. - ANSWER Enzyme lowers the activation energy. Induced fit causes the active site of the enzyme to change shape. Enzyme -Substrate complex causes the bonds to break. Why anti HIV drugs do not destroy HIV in the body but stops or slows the development of AIDS. - ANSWER Initially the person still has HIV DNA in their DNA. So new HIV particles still made. The drug is stopping new HIV particles from forming new HIV DNA. This stops destruction of T cells. So immune system continues to work. The role of single -stranded DNA fragments (template strand) - ANSWER Acts as a template, determines the order of nucleotides Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells - ANSWER Comparisons 1. Nucleotide structure is identical; 2. Nucleotides joined by phosphodiester bond; OR Deoxyribose joined to phosphate (in sugar, phosphate backbone); 3. DNA in mitochondria / chloroplasts same / similar (structure) to DNA in prokaryotes Contrasts 4. Eukaryotic DNA is longer; 5. Eukaryotic DNA contain introns, prokaryotic DNA does not; 6. Eukaryotic DNA is linear, prokaryotic DNA is circular; 7. Eukaryotic DNA is associated with / bound to protein / histones, prokaryotic DNA is not Haemoglobins are chemically similar molecules found in many different species. Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic (evolutionary) relationships between species. Explain how - ANSWER 1. Mutations change base / nucleotide (sequence); 2. (Causing) change in amino acid sequence; 3. Mutations build up over time; 4. More mutations / more differences (in