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Biology
A Level

How does the citric acid cycle work, and what is oxidative phosphorylation?

The citric acid cycle (AKA the TCA cycle, AKA the Krebs cycle) is an incredibly important set of chemical reactions which is at the centre of how all aerobic organisms function. It is ...

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Answered by Frederick H. Biology tutor
4711 Views

What is a randomised controlled trial?

Randomised controlled trials are the most important way that new medical therapies (drugs, devices, procedures and so on) are tested.

‘Controlled’ means that volunteers i...

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Answered by Frederick H. Biology tutor
4339 Views

What causes cancer?

There are lots of different types of cancer which affect different tissues in the body, and two cancers of the same type may not have the same causes. This makes cancer interesting, but also potentiall...

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Answered by Frederick H. Biology tutor
8068 Views

Explain the principles of PCR

The Polymerase Chain Reaction (PCR) is a method of DNA amplification in vitro. It consists of 3 stages - denaturation, annealing and extending. PCR relies on the use of a thermophilic Taq polymerase en...

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Answered by David B. Biology tutor
4725 Views

State the differences between introns and exons.

Introns and exons are parts of genes - exons code for proteins, whereas introns do not, ie: exons are converted into messenger RNA to allow these parts of the gene to then be transcribed into protein. ...

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Answered by David B. Biology tutor
12382 Views

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