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How do vaccinations work? Relating to humoral immunity and the secondary immune response.

The body has both humoral and cell mediated immunity. A vaccination involves injecting a patient with inert (Inactivated) or dead material from a pathogen, be that a bacterium or a virus. Once injected into ...
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Answered by Sophie J. • Biology tutor
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Describe the transmission of a nerve impulse across a synapse.

An action potential arrives at a presynaptic neurone, which causes calcium ion channels to open. Calcium ions enter the presynaptic knob, which causes synaptic vesicles containing neurotransmitter to detach ...
Answered by • Biology tutor
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Give 3 main differences between RNA and DNA.

DNA is double stranded while RNA is a single stranded polynucleotide chain. In DNA the pentose sugar is deoxyribose (one less oxygen containing hydroxyl group) and in RNA it is ribose. In DNA the four bases ...
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Answered by Dora L. • Biology tutor
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How does speciation occur?

A barrier separates the original population into two groups. Due to the different environmental conditions (selection pressures) either side of the barrier, different alleles are selected that better adapt t...
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Answered by Hasna B. • Biology tutor
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Describe how a change in temperature affects enzyme activity.

Enzymes are substrate specific proteins which act as biological catalysts and as temperature increases, we see an increase in enzyme activity. This occurs because an increase in temperature causes molecules ...
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Answered by Freya H. • Biology tutor
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