SCIENCE Two brown-eyed parents can sometimes have a blue-eyed child, and students always want to know how that is possible. The answer lies in the difference between dominant and recessive alleles, one of the most useful ideas in the whole of GCSE genetics. Every trait you inherit is controlled by a pair of alleles, one … Read more
SCIENCE Two students can have completely different eye colours, heights and skin tones, yet still share genes for the exact same conditions without ever showing it. This is where genetics starts to feel confusing, and it all comes down to the difference between genotype and phenotype. Genotype and phenotype sound similar and are easy to … Read more
SCIENCE Look down a microscope at an onion cell and then look at a cheek cell scraped from the inside of your mouth, and you will immediately spot that something is different. Both are living cells, both are eukaryotic, and both carry out the basic functions of life, yet they are clearly built differently. The … Read more
SCIENCE If you have ever looked at a Biology textbook and seen the letters DNA and RNA sitting next to each other and wondered why there are two different molecules doing what seems like the same job, you are not alone. I have taught this topic to GCSE classes for over a decade, and it … Read more
Science Switch off one light in your house and the others stay on. That is because your home is wired in parallel. But in an old-fashioned string of Christmas lights, if one bulb blows the whole string goes dark. That is because they are wired in series. The difference between series and parallel circuits affects … Read more
Science You use acids and bases every single day without thinking about it. The vinegar in your kitchen is an acid. The baking soda in your cupboard is a base. The shampoo you use is slightly alkaline. The lemon juice in your drink is acidic. Acids and bases are everywhere, and understanding the difference between … Read more
Science Every living cell needs energy to survive. But not every cell gets its energy the same way. Animal cells get their energy by breaking down food. Plant cells can do that too, but they can also make their own energy from sunlight. These two processes happen in two different organelles, and understanding the difference … Read more
Science Your body produces hundreds of different chemicals that control everything from your heart rate to your digestion to how you respond to stress. These chemicals are produced by glands, and there are two completely different types of gland in the human body. One type releases its products directly into the bloodstream. The other releases … Read more
Science Plants need to move two things around their bodies: water and food. They have two separate transport vessels to do this, and each one does a completely different job. Xylem carries water up from the roots. Phloem carries dissolved sugars from the leaves to wherever the plant needs them. Students often mix these two … Read more
Science Your heart beats around 100,000 times a day, pushing blood through a network of vessels so extensive that if you laid them end to end they would circle the Earth more than twice. That network has three distinct types of vessel, each with a different structure and a different job. Most students can name … Read more