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What is DNA?

DNA carries the genetic information that codes for instructions in our body and other organisms. DNA is deoxyribonucleic acid. It is found in the shape of a double helix. The conclusion that DNA is in the sh...
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Answered by Vicky B. • Biology tutor
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What is the role of calcium in synaptic transmission?

Calcium is found as an ion, Ca2+ in the extracellular space of the pre-synaptic neuron. The ions enter the neuron through voltage -gated channels after the depolarisation of the pre-synaptic neuron. This cau...
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Answered by Wiktoria F. • Biology tutor
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Inhibitors prevent enzymes from working properly. Explain how a competitive inhibitor works and how it affects the rate of reaction of the enzyme.

Competitive inhibitor molecules are a similar shape to the substrate that fits into the enzyme's active site. The competitive inhibitor competes with the substrate molecules to fit into and bind to the activ...
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Answered by Kirsteen L. • Biology tutor
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Describe the sequence of events which allows information to pass from one neurone to the next neurone across a cholinergic synapse. (6 marks)

(1) An impulse causes calcium ions to enter the axon. (2) Vesicles fuse with the presynaptic membrane. (3) This causes the release of acetylcholine. (4) Acetylcholine diffuses across the synaptic cleft. (5) ...
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Describe the structure and function of the heart valves

There are four heart valves in total. The triscuspid valve is between the right atrium and ventricle. The bicuspid valve is between the left atrium and ventricle. These are the atrioventricular valves and st...
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Answered by Rajan M. • Biology tutor
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