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Biology

A Level

Before a cell divides during the process of mitosis, it must duplicate its DNA. Describe the process of DNA replication.

DNA helicase breaks the hydrogen bonds between the two strands of the DNA helix, separating them. Each strand can then act as a template for the synthesis of new DNA. Free nucleotides can then attach to t...

Answered by Jen C. • Biology tutor

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Describe & Compare the differences in the structure & location of DNA & RNA

Although DNA and RNA belong to the same class of biological molecules, they have many differences in their structure and the location at which they are found.
Firstly, RNA is a single polynucleotide...

Answered by Alisha H. • Biology tutor

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Type 1 Diabetes is an autoimmune disease affecting the bodies ability to produce insulin. Describe how blood glucose is controlled in the body to a stable level, and how this would be affected in someone with type 1 diabetes.

Blood glucose is controlled via a negative feedback mechanism. High blood glucose is detected by B-cells of the Islets of Langerhans in the pancreas, and in response to this, these cells secrete insulin. ...

Answered by William H. • Biology tutor

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One of the most important roles of cell membranes is to control what substances enter and leave the cell. Describe the difference and a briefly outline the mechanism for passive and active transport of molecules over cell membranes.

Passive transport requires no energy and is dependent on concentration difference gradient of intra and extracellular spaces. Channel protein can be opened or closed to allow or stop the free flow of mole...

Answered by Aaron C. • Biology tutor

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