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Describe the effects of cigarette smoke on the airway.

Cigarette smoke contains a number of harmful chemicals such as Tar, Carbon monoxide and Nicotine. Tar settles on the lining of the airway and alveoli, increasing the diffusion distance for the gases oxygen a...
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Answered by Kristen D. • Biology tutor
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What are Enzymes and how do they work?

What is an Enzyme? Enzymes have an essential role in the reactions in the body from respiration to digestion. Enzymes are globular proteins with a specific tertiary shape. Enzymes are Biological Catalysts Su...
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Answered by Katie D. • Biology tutor
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What is the difference between excretion and egestion? Name three major organs of excretion in humans, the substances they excrete and the function of this excretion.

Excretion is the removal of toxic materials, waste products of metabolism and excess substances from organisms. Egestion is the passing out of undigested food as faeces, through the anus. Three major organs ...
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Answered by Lucy W. • Biology tutor
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Why do plants grow towards sunlight?

Plants have adapted to grow towards sunlight - an essential requirement for growth and survival. But how do they do this? An important factor in the control of plant growth is the hormone 'auxin', found with...
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Answered by Rachael D. • Biology tutor
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Which enzymes are involved in digestion?

Several enzymes are involved in digestion. Amylase is produced by the salivary glands and pacreas and starts working as soon as food is ingested, breaking down starch into maltose in the mouth and also the s...
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Answered by Halcyon H. • Biology tutor
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