Open response questions

Extended open response questions require longer answers than structured questions that have fewer marks. Open response questions are usually worth 6 marks, but some are worth fewer marks.

It is wise to plan your answer first by making some notes. This will help you to include all the key points.

To gain full marks, you need to:

  • support explanations using scientific knowledge and understanding
  • use appropriate scientific words
  • write clearly and link ideas in a logical way
  • maintain a sustained line of reasoning

Open response questions often use these command words:

  • Describe means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.
  • Explain means you need to make something clear, or state the reasons for something happening.
  • Compare means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y and give a comparison. Do not just write about X only or Y only.
  • Evaluate means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.

Open response questions may be synoptic questions, which bring together ideas from two or more topics. For example, a question about fertilisers could include ideas about covalent substances, acids and alkalis, chemical calculations and effects on the environment.

The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain full marks, but you do need to write in sentences, linking them logically and clearly.

This page contains AQA material which is reproduced by permission of AQA.

Sample question 1 – Foundation


Light intensity, carbon dioxide concentration and temperature are three factors that affect the rate of photosynthesis.

How would you investigate the effect of light intensity on the rate of photosynthesis? [6 marks]

Below shows some of the apparatus you might use.

a lamp, sample of pondweed, a ruler and a beaker

You should include details of:

  • how you would set up the apparatus and the materials you would use
  • the measurements you would make
  • how you could make this a fair test

Indicative content

  • apparatus set up
    • weed in water in beaker
    • light shining on beaker
  • method of varying the light intensity, eg changing distance of lamp from plant
  • method of controlling other variables
    • use same pond weed or same length of pond weed
    • temperature – water bath or heat screen
    • carbon dioxide
  • leave enough time at each new light intensity before measurements taken
  • method of measuring photosynthesis, eg counting bubbles of gas released or collecting gas and measuring volume in syringe
  • measuring rate of photosynthesis by counting bubbles for a set period of time
  • repetitions

Sample question 2 – Foundation


Plants transport many substances between their leaves and roots.

The diagram below shows the direction of movement of substances through a plant.

A movement diagram of water and nutrients through a plant, along with a cut through of the stem

Describe how ions, water and sugar are obtained and transported through plants.

In your answer you should refer to materials moving upwards in a plant and to materials moving downwards in a plant. [6 marks]

Indicative content

In the points below, P = process; V = vessel; M = material


  • taken up by diffusion or active transport from an area of high to low concentration (diffusion) or an area of low to high concentration (active transport) (P)
  • travels in the xylem (V)
  • to the leaves or from the roots / soil (M)


  • taken up by osmosis
    • from an area of low to high concentration (P)
  • travels in the xylem (V)
  • to the leaves or from the roots / soil (M)
  • transpiration stream (P)
    • movement replaces water as it evaporates from leaves (P)
  • in the xylem (V)


  • made during photosynthesis (P)
  • travels in the phloem (V)
  • to other parts of the plant or to storage organs or travels up and down (M)

Sample question 3 – Higher


A student investigates the rate of respiration in maggots.

This diagram shows the equipment he uses.

A practical set up of the investigation into the respiration of maggots

When maggots respire they take in a gas from the air and release a different gas.

Solution A absorbs the gas released.

At the start of the investigation the student records the distance of the water droplet from the bend in the capillary tube.

Explain what happens to the water droplet as the maggots respire. [4 marks]

Indicative content

  • Water droplet moves towards the maggots / boiling tube.


  • the oxygen in the boiling tube is used up in respiration
  • (and) the carbon dioxide released from respiration is absorbed by solution A
  • which causes a pressure difference
  • so air is drawn into the tube
  • bringing the water droplet with it