Top answers

What are the two main secondary structures of proteins?

Alpha helices and Beta pleated sheets.
UY
Answered by Umamah Y. • Biology tutor
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Megapode birds open and close the air vents of the nest at different times of the day. Suggest reasons why it is necessary to open and close the air vents.

There are a number of reasons why it is necessary to open and close the air vents. These include; allowing oxygen in, which is also necessary for respiration and allowing heat to escape. Closing the air vent...
DR
Answered by Davina R. • Biology tutor
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What is diffusion?

For the exams, the definition you will need to know is that "diffusion is the net movement of a substance from an area of high concentration to an area of low concentration, down a diffusion gradient&qu...
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Answered by Emily R. • Biology tutor
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Describe the regulation of blood glucose level.

The glucose level is regulated in pancreas by negative feedback loop, which means that when there is too much glucose, it is removed from the blood, and when there's too little, it is released into the blood...
JO
Answered by Juraj O. • Biology tutor
9353 Views

Why do the muscles of the Iris contract and relax?

To alter the size of the pupil, so the correct intensity of light is allowed through. Enough light is let through to allow clear vision, but not so much light that the retina might become damaged.
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Answered by Calum M. • Biology tutor
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