7 questions on GCSE science 21 August 2013 Last updated at 01:52 Continue reading the main story GCSE science quiz It's nearly time for GCSE results, but how would you do if you sat the science exam? Questions are from BBC Bitesize and based on the knowledge required by GCSE syllabuses, as actual questions are longer and require full explanations. In about four billion years what will our Sun become? A red dwarf A red giant A red titaness The Sun and other stars eventually begin to run out of hydrogen. Gravity makes the core of the star smaller and hotter, which results in the outer layers expanding. They eventually expand so much the star becomes a red giant. Granite is an example of which type of rock? Igneous Metamorphic Sedimentary Metamorphic rock, which includes marble, has been subjected to heat and/or pressure, causing it to change into another type of rock. Sedimentary rock is formed from sediments that have settled at the bottom of a lake, sea or ocean and have been compressed over millions of years. Why do plants need nitrate ions? To produce proteins To make starch for storage To make fatty acids What is the mass number of an atom? The number of particles it contains The number of protons it contains The number of protons and neutrons it contains What does the epithelial tissue in the stomach do? Produces digestive juices Churns the food Covers the inner and outer surfaces of the stomach What is the official voltage of the mains supply in the UK? It will become a red giant. A red dwarf forms from stars smaller than our Sun. A red titaness is not a category. Click to next page find out more. It's igneous. It is made up of interlocking crystals and forms when molten rock cools slowly below ground. Sodium hydroxide is used to make soap. Plants need nitrate ions to produce proteins. They need protein for growth and repair. The number of protons and neutrons it contains. Atoms are the basic building blocks of ordinary matter. Epithelial tissue covers the inner and outer surfaces of the stomach. It protects the stomach wall, acting as a barrier. Muscular tissue churns the food in the stomach. It's 230V officially. It used to be 240V but was reduced to harmonise with Europe. Brush up on your GCSE knowledge at BBC Bitesize. Adults can improve their general maths and english at Skillswise. Explore more about science and the natural world at BBC Science and BBC Nature.