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Biology
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Gas exchange happens in the alveoli of the lungs. What are three adaptations of the alveoli that allow for this?

  • Thin alveolar walls for O2 and CO2 to travel through - To travel across the membrane, gases have to be dissolved, so the alveolar walls are moist - Large surface area to volume ratio allows for maxi...
SL
Answered by Sarah L. Biology tutor
3197 Views

Describe the process of natural selection

There is genetic diversity within the population. Random mutation can occur, forming new alleles of a gene. Though many mutations are harmful, in certain environments the new allele may benefit its posses...

JJ
Answered by Jewel J. Biology tutor
9280 Views

Explain the roles of ATP and calcium ions in muscle contraction. (4 marks)

The hydrolysis of ATP provides the energy necessary to break the cross-bridges formed between actin and myosin heads. The hydrolysis of ATP is also used to provide the energy for the power stroke, which i...

RH
Answered by Rachel H. Biology tutor
22208 Views

What is ATP and why do we need it?

ATP is short for adenosine triphosphate, and it can be thought of as the energy 'currency' in our cells. It has a similar structure to that of an RNA nucleotide, as it is comprised of a nitrogenous base (...

TD
15193 Views

I feel like I understand the concept, why I am I still not getting full marks on the question?

Understanding concepts in exams is only part of the battle. To improve your marks you need to improve your exam technique!

For example: Have you correctly interpreted what the question is asking of...

TR
Answered by Tom R. Biology tutor
3259 Views

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