The heart's rhythm is regulated by a metronome.  Some people can develop a chaotic rhythm of that metronome, where by the top part of the heart can become chaotic and the heartbeat becomes irregular.  This means that instead of beating regularly like a drum the heart can jump all over the place.

If someone has a leaky valve or a very narrow valve, they may need a heart valve operation where either an animal valve or a special metal valve is put inside the body. If someone has a dental procedure, we know that the bugs from the mouth can spread around the body and those bugs can seed around the heart valve. Antibiotics are given at the time of a dental procedure to people who have had heart valve surgery to prevent that seeding from occurring.

Actually cholesterol does a lot of good in our body: it's a component in our hormones such as testosterone and oestrogen, it's also responsible for helping to absorb other fats and it also helps making the lining of cell membranes. If someone completely removes all the cholesterol from their diet, then the body will be able to synthesis more cholesterol. However diet only makes one percentage of the cholesterol we take and there are people who have high cholesterol level where the cholesterol thermostat is impaired, those people have to go on special drugs to reduce their cholesterol levels.

There are a wide range of leakiness of different heart valves.  A mild degree of leakiness of particular heart valves is not always necessarily sinister, but if someone has a very leaky heart valve left untreated it could be fatal.  If you have been told that you have leaky heart valve, it's worth asking about how leaky it is and what can be done about it.

We need some amount of stress in our lives.  Stress gives us motivation and enthusiasm.  Some people however would suffer a heart attack when they are feeling especially stressed, but it's likely that the heart attack would probably have occurred anyway.  If you don't have narrowing in your arteries, stress on it's own would not bring about a heart attack.

Generally the left side of the heart is bigger than the right.

A palpitation is when someone is aware of their own heart beating. That's quite common and I'm often aware of my own heart beating specially when I'm in bed going to sleep, but being aware of your heart beating is not necessarily abnormal. Lots of things can cause palpitations, but the times when it requires investigation is when someone is aware of their heart beating and feel very unwell, or when their heart beats quickly for a long time or they feel light headed. Sometimes it can be normal and sometimes it requires further investigation.

The heart has a very well designed electrical system, which has it's own internal pacemaker that beats very regularly, a bit like a metronome. That metronome will speed up if the heart needs to beat faster, for example at times of exercise or stress. The heart will beat slower when we are relaxed, for example when we are resting or when we are asleep at night. The heart has a well regulated metronome, however there are some conditions where that metronome can become damaged or impaired. In these cases we can fit the person with a pacemaker, which is a small box that sits just underneath the person's collar bone and feeds wires inside the heart; taking over the heart's own pacemaker at times when it becomes impaired.

Yes it can be true.  If you heat water very gently in a very clean container, you can actually get it to be above 100°C, maybe 105°C or 106°C.  So if the temperature of the water is 105°C it will do you more damage more quickly. Also if you put in some sugar then it will boil quickly and explode all over you, and some people have been badly hurt by putting spoons into things and heating it in the microwave.

Peanut butter is rich in vegetable oil and that means it has unsaturated fats in it. An unsaturated fat has double bonds between the carbon atoms, which cause the hydrocarbon chain to bend. This bending causes the molecules not to stack together tightly, which means that the peanut butter is less dense and therefore will spread more easily than something that contains saturated fats.

Saturated fats have single bonds between the carbon atom so they stack together more closely and are very dense. So because butter is more dense, it's harder to spread than peanut butter. This means that butter forms globules and sticks to itself rather than spreading out evenly on the bread.

It might also be that if the bread has just come out of the oven, it's still warm and the melting point of unsaturated fats is lower than saturated fats, so the peanut butter (unsaturated fat) would get runnier (start to melt) quicker and becomes easier to spread.

I have tried this at my girlfriend's house and it did actually cut out the phone connection, so the microwave oven does keep some of the microwaves coming out of the phone, inside the microwave (oven).  The frequency of the microwaves from a phone is not the same as the microwaves you use for cooking, if they were the same, then every time you turn the microwave on you wouldn't be able to talk on the phone, because you would get horrible interference.

In fact there is a gap (between the door and the main body of the oven), but the microwaves don't get out of this gap, because it's (the gap) tuned to be exactly a ¼ of the wave length of the microwaves.  As the phone works at a different frequency, some microwaves from your phone will get out of this gap.  So the oven will cut down the microwaves (from the phone) coming out of it but it won't cut it out completely because it's the wrong frequency.  On the other hand, the phone will also turn up it's power to make itself work!

Identical twins do have identical DNA. They form when a fertilised egg, (that is when one sperm has joined with one egg to form a growing embryo) splits in two and it develops independently as two separate embryos. Because both halves originated from the same genetic material they are genetically identical. They are nature's clones and happen naturally in humans and some animals. In fact the nine-banded armadillo naturally produces four genetically identical offspring.

So twins are genetically identical but fingerprints differ amongst identical twins. The reason is that fingerprints are a developmental random process. When cells are migrating in the body, there are codes and chemical messages that tell them where to go in the body to put the body together, but when the cells get to their final destination, how they arrange themselves is much more random. Fingerprints are a consequence of this arrangement, so you will see a very individual picture to a person’s fingerprints but of course their genetic fingerprint is going to be the same.

So your DNA doesn't tell you exactly how to build you! It's a bit like giving someone building instructions on how to build a wall, it doesn't tell you exactly where to put each of the bricks?