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Describe what each point of an ECG represents.

P wave: atrial depolarisation and subsequent contraction. QRS complex: Ventricular depolarisation and subsequent contraction. Q wave is negative due to left to right depolarisation of ventricular septum. Atr...
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Answered by Humza C. • Biology tutor
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Explain how the alveoli create a surface for efficient gaseous exchange

Firstly, the alveoli walls consist of a one-cell thick layer of squamous epithelium. This means there is a thin barrier to diffusion, and a small distance for oxygen molecules to diffuse across to get to blo...
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Answered by Humza C. • Biology tutor
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How are some plants able to fix gaseous nitrogen from the atmosphere?

Leguminous plants have nodules on their roots that contain, symbiotic bacteria. These bacteria are capable of turning gaseous nitrogen ultimately to nitrate, which the plant can then use in order to synthesi...
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Answered by Sam C. • Biology tutor
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What is the difference between osmolarity and osmolality?

First of all, it is important to define osmosis. If you have two solutions separated only by a semi-permeable membrane, and one solution is more concentrated than the other, then water will move from the les...
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Answered by Kelly W. • Biology tutor
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What are the 3 ingredients required for evolution to occur?

For a trait to evolve, firstly, there has to be genetic variation among individuals, which will lead to differences in phenotype and cause differences in fitness in a particular environment. These difference...
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Answered by Ana D. • Biology tutor
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