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Biology

A Level

How does the kidney work?

The kidney is the body's filtration system, and works by separating the fluid and cells that make up blood, then selectively reabsorbing what is still useful, so that we don't lose anything valuable but c...

Answered by Nkosi Y. • Biology tutor

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When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how. (5 marks)

With these 5 and 6 mark questions, one of the main skills required is being able to describe the process in sufficient detail, without wasting time with unnecessary information. For example in this questi...

Answered by Thomas R. • Biology tutor

17166 Views

How do we control the concentration of urine?

Osmoregulation is the homeostasis of water in the body. It is important that water volumes are kept relatively constant as this influences electrolyte concentrations and cell activity.

Answered by Adam B. • Biology tutor

2403 Views

What does the term "Semi-conservative" mean in relation to DNA?

DNA is a double stranded helix. During DNA replication, the strands are separated from each other (using an enzyme called DNA helicase). The unzipped DNA strands then utilize another enzyme, known as DNA ...

Answered by Catherine A. • Biology tutor

3871 Views

Explain the role of T-cells in immune response to viral infection

When T cells bind to viral antigens presented by macrophages they undergo mitosis to form 4 distinct cell variants:
Memory T cells- remain in the blood stream to initiate a faster immune response upo...

Answered by Will S. • Biology tutor

5352 Views