Top answers

What is a protein?

A protein is a sequence of many amino acids. All proteins are made of amino acids. Humans have 20 distinguished amino acids that can arrange in thousands of different combinations and this means that they ca...
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Answered by Matilde M. • Biology tutor
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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 a reflex action?

A reflex action is the body's rapid, involuntary response to external stimuli, often used in order to protect it from immediate harm. First, a receptor detects a stimulus, such as a heat source which could b...
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Answered by Nat A. • Biology tutor
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