You will have heard of diffusion, osmosis and active transport in your science lessons. However, what do they really mean to you? You might think you have a great sense of smell, being able to identify what is cooking for dinner from upstairs! This is due to the process of diffusion. Compared to other animals however, we cannot smell well at all.
Take grizzly bears for example, although they have really poor eyesight, they are ferocious predators. Their extremely sensitive noses assist them greatly with this, enabling them to smell things up to 30km away. It is thought that the bear’s sense of smell is up to 100,000 times stronger than a human’s. They have honeycomb-like tissue in their nasal cavity, which helps them smell fish underwater, and detect clams underground.
Mosquitoes are brilliant hunters at night. Scientists have discovered a chain of proteins which help them to smell humans. These proteins build up at night. This helps mosquitos smell the carbon dioxide we exhale, and our bare skin. They can smell us from around 30 metres away!
The common mole uses each nostril to calculate where a smell is coming from in seconds. Sharks and ants can also do this – but until recently, scientists did not believe any mammals were able to use nostrils separately!
GCSE scientists – you need to be able to explain what osmosis is, and where it happens in living organisms. You also need to describe different ways substances can be transported, including diffusion and active transport. For help, try our “How to work with Diffusion, Osmosis and Active Transport” revision guide. It includes information on the different methods of transport. There are also questions for you to try, and answers to check your understanding.
Click on the picture below to see the guide:
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