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Describe the stages of transcription

Transcription begins with DNA helicase unwinding the DNA into two seperate strands.As the DNA unwinds, RNA nucleotides form hydrogen bonds with their complementary base pairs. Uracil binds to adenine, and gu...
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Answered by Edward A. • Biology tutor
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Explain how you would test for the presence of lipids and proteins in an unknown solution. Give details on any observations you would expect to make.

To test for the presence of lipids, you would carry out the emulsion test. To do this, you take the sample and mix it with equal volumes of ethanol and water followed by shaking. A cloudy white emulsion will...
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Answered by Chelsea J. • Biology tutor
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How are grana adapted to their function in photosynthesis? [2 marks]

They contain photosynthetic pigments to absorb light i.e. chlorophyll a2. They have a large surface area for light absorption3. They contain electron carriers / ATP synthase
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Answered by Amaani I. • Biology tutor
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What is the function of the mitochondria?

The mitochondria is an organelle in the cell which is used as a "power station" to provide the cell with energy in the form of ATP. It uses substrates like glucose, which is broken down in the cyto...
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Answered by Hamzah A. • Biology tutor
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Two species of frogs, each found on one of two neighbouring islands yet with the same genus, are identified. Scientists believe that the two species originated from a common ancestor. Explain how these species could have evolved.

Questions about speciation are at their core based on Darwin's theory of evolution. As a result, we must recall GCSE knowledge of natural selection to combine with the new concepts in speciation introduced a...
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Answered by Iqra S. • Biology tutor
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