When you make a cake, you mix together fat, sugar, flour and eggs. To make the batter, eggs have a very important property that means they can emulsify things. In other words, eggs contain lipoproteins that can stick fat into a liquid. So you mix together fat, flour and sugar and make a cake batter. When you put it in the oven, the fat melts and the air that's been beaten into the cake expands into the gaps. This makes the cake rise. The protein that's in the egg whites solidifies and holds the whole cake structure as a stable thing. This means that when it comes out the oven, it doesn't just flop down. If you've got baking powder in there as well, that releases carbon dioxide which is another gas that expands and makes the nice big gaps in your lovely fluffy cake. That's why eggs make things rise. They make everything stick together and then hold it together as a solid protein structure. The yeast story is similar. Yeast is a type of fungus and when you warm up your bread mixture of flour and water, they create carbon dioxide. That creates the holes in your nice fluffy bread and a little bit of alcohol too!

It's pretty well known how chameleons change their colour. Lots of people think they change colour to match in with their surroundings but it's not actually true. Chameleons change colour to signal to other chameleons what kind of mood they're in. The usual calm chameleon is a pale green colour. So when you see them in Madagascar and Africa which is actually where they're most common, they're that light pale green colour. If you warm them up and put them into a bad mood, they can flash red and yellow and all kinds of funny colours. When they get a bit frisky, they also change colour to attract a mate. But how do they actually do that? It's all down to a very clever system that's not dissimilar to a television screen. In a chameleon's skin, they have these things called chromatophores and these are tiny cells that are laden with pigment. In a normal cell, the pigment is locked away in these tiny vesicles or pouches inside the cell. When a signal comes in from the nervous system or a chemical in the bloodstream, they cell discharges that pigment and it spreads out in the cell and causes the cell to change colour. Depending on which sets of these chromatophores get discharged, then the chameleon changes colour accordingly.

Here in Cambridgeshire and Peterborough, we only accept plastic bottles for recycling, and that's the guidance we give our public. Basically, the reason we ask for bottles is because they are made from three different types of plastic which we know that we are readily able to recycle. These are PET, PVC and HDPE. So if you stick to bottles the likelihood is that it will be one of those three types of plastic.

That's a difficult one. I'm surprised that he's been told that because all supermarkets usually have recycling schemes now so that you should be able to take your plastic bags back to the supermarket so you can get them recycled regardless of whether they're biodegradable or not. The best thing to do in the first place is not to use plastic bags, or take them back and reuse them so you don't get this build up of plastic bags in your kitchen drawer. Best of all is to get a bag for life or a reusable bag.

Actually they don't anymore. Historically we did reuse syringes and those are the ones made of glass, but nowadays it's much cheaper to make them out of plastic. They then end up on the beach of course and Richard Thompson has to pick them up in his marine ecology studies.

If you wanted to define whether there would be enough land, you could give everyone a metre-squared of the Isle of Wight for the moment but that's not really survivable. In terms of the poles melting, people say it's really bad news if the poles melt, but it's not. If the North Pole disappeared tomorrow, there wouldn't be any change in sea level. The reason for that is that it's entirely made of ice and ice is floating. As you know, ice is made of water and weighs the same as water. The amount of water level change is proportional to displacement so if the North Pole melted we wouldn't be in much trouble. The real worry is ice on land, so that's Greenland and the South Pole. If that melts, we are in trouble. Predicted sea level rises for the next 100 to 200 years is anything from a few centimetres maybe to as much as seven metres over the next 700 years. But it's not just the melting of the water. If the planet warms up, things will start to expand. Just the getting warmer effect is enough to make the water expand a bit and to increase in depth. In fact, the melting of the ice on Greenland alone is contributing to about a 0.5 centimetre rise in ocean levels everywhere every year.

I don't think that's true. I know that there are a number of plants up and down the country. It's a stage process so you have reprocessing plants and mills. The UK paper recycling industry is big on its own so it doesn't need to import or export wood from outside. Often there is an amount of recycled material that is exported, such as green glass, because we just don't have the market for it in this country in terms of the glass production. But the transport costs are offset by the energy saved by recycling in Europe.

I guess what you're talking about is why we don't use seawater to drink. We could and it's perfectly possible from a technical point of view but it's going to cost us a lot of money and a lot of environmental damage to do it. It uses a huge amount of energy. People in dry places like Las Vegas pipe in water over very long distances which costs a lot on pumping costs.

I believe it's because small shreds of paper would clog up the paper reprocessing system but I think it depends on your local authority and the paper mill it goes to. Of course you can also compost shredded paper, which is a nice alternative.

The answer is that anti-diarrhoea tablets like Imodium contain a version of morphine and they're a morphine-like drug which has some morphine-like effects without all of the morphine effects. It doesn't make you fall asleep or make you feel high for example. One side effect of morphine or morphine-like drugs such as heroin is that it switches off the bowel. In other words it converts motility or movement through the bowel into backwards and forwards mixing motions. That's why people who tend to take a lot of morphine for pain or due to being a drug addict get very very constipated. What scientists have been able to do is to find which bit of the morphine molecule works and makes that effect, made a molecule that mimics that effect and put it in a tablet form.