WJEC Biology for A2: Study and Rev Guide

Some examples requiring description: ■ Describe how biodiversity loss could be delayed. (1 mark) ■ Describe how a sweep net could be used to estimate the diversity index of insects at the base of a hedge. (3 marks) Some examples requiring explanation: ■ Suggest one limitation of the method used, and explain how this could have affected the validity of the conclusion drawn. (2 marks) ■ Explain why there must be three bases in each codon to assemble the correct amino acid. (2 marks) ■ Explain the term planetary boundary. (2 marks) ■ Explain why it is important when using a biosensor to measure urea concentration to maintain a constant temperature and pH. (2 marks) ■ Explain how the structures of cellulose and chitin are different from that of starch. (2 marks) Some examples requiring application: ■ Suggest the function of NAD in the series of reactions shown. (1 mark) ■ A drug has been shown to block the initiation of S phase in mitosis. Suggest why this could be used to treat cancer. (3 marks) ■ Use the information provided to explain why sodium benzoate would affect the accuracy of the biosensor. (5 marks) Some examples requiring evaluation: ■ Describe how you could improve your con dence in your conclusion. (2 marks) ■ Analyse the data in the table and draw alternative conclusions. Explain how you reached these conclusions. (3 marks) ■ Evaluate the strength of their evidence and hence the validity of their conclusion. (4 marks) 2. Extended response questions One question in each component exam contains an extended response question worth 9 marks. The quality of your extended response (QER) will be assessed in this question. You will be awarded marks based upon a series of descriptors: to gain the top marks it is important to give a full and detailed account, including a detailed explanation. You should use scienti c terminology and vocabulary accurately, including accurate spelling and use of grammar and include only relevant information. It is a good idea to do a brief plan before you start, to organise your thoughts: You should cross this out once you have nished. We will look at some examples later. 159 Exam practice and technique