Using past papers effectively - Edexcel biology

Practising questions will help you to prepare for your biology exam. By working through example problems, you can build your confidence and sharpen your understanding of key topics.

These worked examples not only show you how to approach problems step-by-step but also include tailored tips for each topic to help you develop the skills to tackle similar questions on your own.

Use these questions to identify areas you feel confident in and those that need more practice.

Remember, the questions on the exam paper are not released until the day of the exam. The examples on this page are a guide to the topics and question structures that could be on the paper.

1. Show evidence

Past paper trend: Questions on evolution often ask for evidence for this process.

Revise examples of evidence for evolution but be prepared for unfamiliar examples. Focus on identifying the process that the question is about. If the organism hasn’t been bred by humans (pets, farm animals and crops are examples of organisms which are bred by humans), the question is likely about evolution. Common examples include the fossil record, the peppered moth, antibiotic resistance in bacteria and Darwin’s finches on the Galápagos Islands.

2. Know the processes

Past paper trend: Evolution is one of the three ways organisms change or are changed which you may be asked about in the exam.

As well as evolution, revise the processes of selective breeding and genetic engineering. This is also called genetic modification.

Selective breeding is when humans breed plants or animals for particular genetic characteristics so that they are different to their actual wild ancestors and are now beneficial to humans. Examples include breeding dogs from wolves and developing cauliflower, cabbage and broccoli from wild mustard.

Genetic engineering involves modifying the DNA of an organism by introducing a gene from another organism to result in a described characteristic. Plant crops have been genetically engineered to be disease resistant and to produce bigger fruits. Genetic engineering is an ethical issue - some people disagree with it for religious or moral reasons.

3. Know the history

Past paper trend: Questions are often asked about the work of scientists Alfred Russel Wallace, Jean-Baptiste Lamarck and Gregor Mendel.

Revise the work of these three scientists. Gregor Mendel first studied the inheritance of different characteristics in pea plants. When he bred plants with red flowers and white flowers all the offspring had red flowers. When he then bred the offspring many had red flowers but some had white ones. He developed this into his Laws of Inheritance.

Jean-Baptiste Lamarck developed a different theory of evolution before Darwin. He proposed that any characteristic used more and more by an organism became bigger and stronger and one that was not used disappeared. He proposed that these bigger and stronger features could be passed to offspring. We now know that in the vast majority of cases this is not true.

Alfred Russel Wallace independently developed the theory of evolution after Darwin and they published their findings together. Wallace is also recognised for his pioneering work on speciation.

Here is an example of the type of question you may encounter in the exam and an example answer with an explanation of how the marks have been awarded.

Practise the process of writing a short plan for all six-mark questions.

Spending one minute planning and five minutes writing often scores more highly than just jumping in and writing for six minutes. Try to make as many key points as there are marks on offer. For this six-mark question try to write a minimum of six points.

1. Learn about experiments

• Past paper trend: Enzymes questions are often linked to experiments.
• Exam tip: Revise the required practical for Edexcel. A common one involves investigating how pH affects enzyme activity using amylase to break down starch. Practise writing the method for this experiment. The independent variable is pH, which is changed. The dependent variable is the time taken for the iodine solution to stop turning black, indicating the starch has broken down. A controlled variable to keep constant is the temperature.

2. Practise drawing graphs

• Past paper trend: You're often required to draw a graph from a table of data and then describe or explain it.
• Exam tip: Take care when drawing the graph and use a pencil so it's easy to correct mistakes. Ensure each point is plotted accurately. If asked to draw a line of best fit it should be a straight line or smooth curve that passes through as many points as possible. Check whether the question asks you to describe or explain the graph. If you are describing, state what you see. If you are explaining, provide a reason, often using the word 'because'.

3. Know how to calculate

• Past paper trend: You may be asked to calculate the mean rate of a reaction for a certain length of time or the rate at a specific point.
• Exam tip: To calculate the mean rate of reaction for the first five minutes (as an example) move along the horizontal axis (x-axis) to the specified time point. Draw a vertical line upward until it meets the line of best fit then draw a horizontal line to the left toward the vertical axis (y-axis). Divide the value on the y-axis by the corresponding value on the x-axis to determine the rate. When calculating the rate at a specific point draw a large tangent at that point. The rate is determined by finding the gradient of the tangent, calculated by dividing the change in the y-axis by the corresponding change in the x-axis.

1. Learn the sampling methods

• Past paper trend: Sampling methods using quadrats can be either random or systematic.
• Exam tip: Revise these two different methods that both use quadrats.

Random sampling is employed when the aim is to estimate the number of organisms in one or more areas. In this method quadrats are placed randomly ensuring unbiased data collection and providing reliable population size estimates.

Systematic sampling is used to study the distribution of organisms. This involves placing quadrats at regular intervals along an imaginary line known as a transect. At each location abiotic factors such as soil pH or water content are recorded alongside observations of the organisms. This approach seeks to uncover the relationship between these abiotic factors and the presence or distribution of the sampled organisms.

2. Learn the averages

• Past paper trend: You might be asked to calculate the mean number of organisms per quadrat or identify the median or mode.
• Exam tip: Mean, median and mode are the three most commonly used types of averages.
  • The mean is calculated by summing all the values and dividing the total by the number of values.
  • The median is determined by arranging the numbers in order of size and identifying the middle value. If there is an even number of values the median is the mean of the two middle numbers.
  • The mode is the value that occurs most frequently in the dataset.

3. Make sure you can use them

• Past paper trend: You may be asked to estimate how many organisms there are in a population from a given sample.
• Exam tip: The first step is to calculate the mean for one quadrat (see tip two above). If the quadrat is not 1 m² then the mean number of organisms in one quadrat is multiplied by the factor required to make the area 1 m². Many questions involve quadrats of 0.25 m². So the mean number of organisms in this area would be multiplied by four for an area of 1 m². The number of organisms in 1 m² is multiplied by the total area in m² to estimate the total population.

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