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Explain how the physical properties of water enable organisms to survive over a range of temperatures.

Water has a very high specific heat capacity due to the collective forces of the many hydrogen bonds. A lot of energy goes into breaking these bonds rather than raising the temperature of the water, hence pr...
AB
Answered by Arunima B. • Biology tutor
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How is the the small intestine adapted for absorption?

The Ileum is long (up to 7m!) and has a very high surface area due to the presence of many villi and microvilli . A single villus is made up of many cells, each with lots of microvilli, and have many blood v...
JP
Answered by James P. • Biology tutor
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Tetrodotoxin (TTX) is a chemical found in pufferfish which binds to voltage-gated sodium channels causing inactivation via a conformational change. Poisoning can result in paralysis leading to death. How might this occur? (4 marks)

This question asks about nerve action potential generation. There are a couple of clues - these include 'voltage-gated sodium channels' and 'paralysis' which suggests the idea of failure of impulse transmiss...
RA
Answered by Rafee A. • Biology tutor
5509 Views

What are the main stages of the cardiac cycle?

Blood enters the atria. It cannot pass into the ventricles because the atrioventricular valves are closed. The heart is in diastole.The atria contract. The pressure in the atria becomes greater than the pres...
AA
Answered by Anshul A. • Biology tutor
5423 Views

How are leaves adapted for gas exchange?

Leaves have a large surface area, which means more space to allow CO2 to enter. They are thin so there is less for gases to travel. Leaves contain Stomata; these are small holes found distributed throughout ...
AM
Answered by Anika M. • Biology tutor
44094 Views