One to four mark questions will start with command words such as 'describe' or 'explain'. Some command words are easy to understand such as:
The command words 'describe' and 'explain' can be confusing. If you are asked to describe a graph, you will be expected to write about its overall shape, whether it is linear or curved, the slope of gradients etc. If you are asked to explain why a pattern or trend is seen in a graph, you will be expected to use your science knowledge, not just say what you see (which is a description), eg the graph shows a steep linear increase for the first three hours because…
Explain how and why questions often have the word 'because' in their answer. Describe questions don't.
The number of marks per question part is given in this form '[2 marks]'. It is essential that you give two different answers if a question is worth two marks. Sometimes you can gain a second mark by giving the units in a calculation or stating specific data points, eg during the first two years the number of lions deceased by seven.
You will be expected to write in more depth for three and four mark questions. They might ask you about a process such as the carbon cycle or the method you would use in an experiment.
These questions have been written by Bitesize consultants as suggestions to the types of questions that may appear in an exam paper.
Explain the difference between sensory, relay and motor neurones in terms of the direction that their electrical signals travel. [3 marks]
Explain why reflex arc signals do not immediately go to the brain. [2 marks]
Describe how are embryonic and adult stem cells different? [2 marks]
State what types of human cells are not produced by mitosis? [1 mark]
Gametes (sperm and ova) 
Name the type of cell in plants that can differentiate into different types of cell. [1 mark]
Meristem cell or meristematic cell. 
Note that you must be specific. It isn't sufficient to call it a 'stem cell', as stem cells occur in animals.
Why is the use of unused embryos left over from in vitro fertilisation an ethical issue? [1 mark]
Some people disagree with it for religious or moral reasons.