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What is a hormone?

A hormone is a chemical messenger. Just remembering these two words gives you a starting point to explain the properties of a hormone in as much detail as you need. We'll break it down: A) Chemical: a hormon...
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Answered by Rachel T. • Biology tutor
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What is the structure of an animal cell?

At GCSE level, you probably looked at the basic structure of an animal cell comprising the cell membrane, cytoplasm and nucleus. These are all that is normally visible of a cell when you look at it under a l...
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Answered by Calum M. • Biology tutor
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Describe how Carbon Dioxide is assimilated in the Calvin cycle.

CO 2 from the atmosphere diffuses into the leaf through the stomata and then into the stroma within the chloroplasts of mesophyll cells. In the stroma the enzyme Ribusco catalyes the combining of CO 2 with r...
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Answered by Victor A. • Biology tutor
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What precisely is autoregulation in the kidney? Is it solely the ability to vary the diameters of the afferent and efferent arterioles? If so how is this controlled?

Autoregulation is the ability of any vascular bed to maintain its capillary blood supply/perfusion pressure fairly constant despite changes in mean (systemic) arterial pressure. Autoregulatory control must b...
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Answered by Steffi M. • Biology tutor
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How does gel electrophoresis work to separate DNA fragments of different lengths and how may the lengths of the different strands then be determined?

The process of gel electrophoresis uses the fact that DNA fragments are negatively charged (due to the bulky, negative phosphate groups within the sugar-phosphate backbone) in order to pull the fragments thr...
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Answered by James P. • Biology tutor
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