WJEC Biology for AS Level Student Book: 2nd Edition

Assessment Assessment Objectives Examinations test your subject knowledge and the skills associated with how you use that knowledge. These skills are described in Assessment Objectives. Examination questions are written to reflect these objectives, with marks in the proportions shown: AO1 AO2 AO3 AS Level 35% 45% 20% You must meet these Assessment Objectives in the context of the subject content, which is given in detail in the specification. The AS Biology specification stresses the importance of your ability to select and communicate information and ideas, using appropriate scientific terminology. This will be tested within each Assessment Objective. The Assessment Objectives are explained below, with examples of how they are tested. The mark schemes for these questions are on page 259. Assessment Objective 1 (AO1) Demonstrate knowledge and understanding of scientific ideas, processes, techniques and procedures. This AO tests what you know, understand and remember. It is a test of how well you can recall and explain what is relevant. That is why it is essential that you learn facts, concepts and information by heart. In addition, understanding more complex concepts requires you to have a body of knowledge. Ensure that you know the content of the specification, e.g. by making lists, and drawing and annotating diagrams from memory. Read your notes and repeat them out loud; test your friends and relatives; ask them to test you; read the same information in at least three different textbooks, including those designed for other examination boards. Each book will explain slightly differently, and you may find one of those explanations better suits your way of thinking. The questions that test this AO are often short-answer questions, using words such as ‘state’, ‘explain’ or ‘describe’. Here are two examples: AO1 Demonstrate knowledge Infection with Salmonella can cause food poisoning. Salmonella , like other bacteria, has a cell wall surrounding its cell membrane, which encloses its cytoplasm and genetic material. Describe the differences between the genetic material of Salmonella and the genetic material found within the nucleus of the human cells that it infects. [3] This question tests AO1 because it asks you to recall factual information. AO1 Demonstrate understanding of scientific ideas Explain why maltose ( α -glucose- α -glucose) and lactose (glucose-galactose) are described as structural isomers. [1] This question tests AO1 because it asks for an explanation based on your factual knowledge. Assessment Objective 2 (AO2) Apply knowledge and understanding of scientific ideas, processes, techniques and procedures: ▪ in a theoretical context ▪ in a practical context ▪ when handling qualitative data ▪ when handling quantitative data. AO2 tests how you use your knowledge and apply it to different situations, in the four possible ways shown above. A question may present you with a situation that you may not have met before, but it will give you enough information that you can use what you already know to provide an answer. Make sure you understand the method of all the experiments you have done. For each one, make sure you can state the independent, dependent and controlled variables, the experimental control, the risks, the hazards and how to minimise them. Be sure you understand how to do all the calculations needed to process the results. In testing AO2, a question may have command words such as ‘Using your knowledge of…’ or ‘Explain…’. Here are two examples: AO2 In a theoretical context A student tested geranium leaves for the presence of starch. The procedure included taking the leaves from boiling water and placing them in ethanol at 50ºC for 20 minutes. Using your knowledge of the structure of biological membranes, explain why ethanol caused pigments to leak out of the spinach cells. [2] ‘Using your knowledge’ indicates that you should use your theoretical knowledge and understanding to explain a biological observation. AO2 In a practical context Site in relation to sewage outlet Nitrate concentration / mg dm –3 Flow rate / m s –1 Light intensity / lux Mean number of flatworms per sample Upstream 0.9 0.8 3000 9 Downstream 15.1 5.2 800 23 The table shows a student’s data from an experiment to determine the relationship between nitrate concentration and the number of flatworms in a freshwater stream. The conclusion of the experiment was that increased nitrate Introduction 7