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Biology
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How is a concentrated filtrate produced in the kidney to remove harmful toxins from the body?

To begin with, sodium ions are actively (using ATP) pumped out of the ascending limb of the loop of henle, however, as the ascending limb is impermeable, water remains . This creates a lower water potenti...

DW
Answered by Dan W. Biology tutor
2651 Views

How may allopatric and sympatric speciation be distinguished? (4 marks)

First it is important to establish what a species is. A species is a population of similar organisms that can interbreed to produce fertile offspring; meaning they are reproductively isolated from other s...

GL
Answered by Gabrielle L. Biology tutor
5372 Views

Describe the structure of the heart and its function in the human circulatory system.

The heart is a muscular organ composed of 4 chambers; the left atrium and right atrium (pl. atria) and the left ventricle and right...

AO
Answered by Aine O. Biology tutor
17459 Views

How are veins and arteries adapted to the transport of blood?

Artery walls are made up of smooth muscle tissue and a thick elastic layer which allows them to expand and contract easily, coping with the changes in blood volume that occur with each heartbeat. The musc...

AL
Answered by Amélie L. Biology tutor
3137 Views

Describe the process of DNA replication

In DNA replication, first the hydrogen bonds between the nitrogenous bases are broken catalysed by the enzyme helicase, causing the DNA double helix to unwind and unzip, leaving the nitrogenous bases expo...

HN
Answered by Helena N. Biology tutor
12219 Views

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