This is the most common question on exam papers, although the number of marks for each question may vary.
At its simplest, this type of question will ask you to remember a simple fact that you have been taught. This type of question is likely to be worth one mark, and will often start with 'Give...', 'State...' or 'Name..'. In some cases, a question may ask you to state two things, rather than just one, and will be worth two marks.
Other structured questions may be worth two or more marks. These will often start with a command word such as 'Describe...' or 'Explain...', and will require a more detailed answer:
More complex structured questions will be worth three or four marks. They include questions with complex descriptions and explanations, questions in which you need to compare and contrast two different things, or calculations with several stages.
The mark schemes given here may show answers as bullet points. This is to show clearly how a mark can be obtained. However, it is important that your answer is written in a logical, linked way. Examiners will not credit a key word if it is used out of context, or if your answer contradicts itself.
Questions courtesy of Eduqas.
Describe how volcanoes contributed to the appearance of oxygen in the atmosphere. [2 marks]
a) The following processes are used in the treatment of our water supply. State the purpose of each process.
iii) chlorination [3 marks]
b) Drinking water can be obtained by desalination. State what is meant by desalination and name a process by which it can be carried out. [2 marks]
a) i) Sedimentation - removes large particles/objects 
ii) Filtration - removes smaller particles 
iii) Chlorination - kills bacteria 
b) The removal of salt from seawater 
Explain how the change in concentration of carbon dioxide in the Earth's atmosphere is believed by most scientists to be causing sea levels to rise. [3 marks]
Many scientists believe that an increase in the use of fossil fuels has led to global warming.
a) Describe how global warming is different to the greenhouse effect. [1 mark]
b) Describe two possible consequences of continued global warming over the next century. [2 marks]
a) Greenhouse effect is a natural process but global warming occurs when this effect becomes stronger as a result of increased amounts of carbon dioxide/greenhouse gases being released to the atmosphere. 
b) Any two of the following for  each: