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What is an allele?

In the nucleus of the cell, there are pairs of chromosomes which carry the same genes in the same places. 2) Alleles are different versions of these genes.3) For example, a person may have an allele for brow...
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Answered by Ella S. • Biology tutor
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Why do we vaccinate people - how does it work?

Vaccination is an important method used in healthcare to prevent people from getting certain diseases. Vaccines contain a dead or weakened ( attenuated) form of a pathogen, and the immune system responds to ...
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Answered by Ella S. • Biology tutor
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Rationalising the denominator (Surds)

When asked to rationalise simple Surd (square roots that cannot be reduced to a whole number) fractions in the form a/√b we are aiming to remove the surd in the denominator (bottom).-------------------------...
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Answered by Galen Y. • Maths tutor
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Explain the trend in ionisation energy down group 2? (3)

• down group 2 the number of protons increases therefore the nuclear charge increases (protons are found in the nucelus and have a +1 charge) • the number of shielding electrons increases ( each member down ...
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Answered by Flora J. • Chemistry tutor
14382 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 enzyme.
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Answered by David B. • Biology tutor
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