Top answers

How does helicobacter pylori cause stomach ulcers?

It neutralises acid in the stomach and allows bacteria to damage the stomach epithelium.
SG
Answered by Saranya G. • Biology tutor
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Before a drug is sold and released to the public, what measures must scientists take to ensure the safety of a drug and why are these steps taken?

Phase I- The drug must be tested on animals and tissue culturesPhase II - The drug is tested on healthy volunteers in small dosesPhases III- The drug is tested on sick patients in small dosesSmall doses are ...
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Answered by Saranya G. • Biology tutor
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What are the non-specific defence systems of the body against pathogens?

There are four main non-specific defence systems, all of which are immediate and the same for all pathogens (hence 'non-specific).1) skin: it acts as a primary defence mechanism as the dry, dead cells on the...
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Describe the differences between DNA and RNA?

DNA is: - double stranded- has thymine as a base- longer RNA is:- single stranded- has uracil as a base (instead of thymine)- shorter
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Answered by Muhammed M. • Biology tutor
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What is a tropism

Tropism is directional growthPhototropism is directional growth in response to light.Negative phototropism is growing away from the light e.g. in the rootsPositive phototropism is growing towards the light e...
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Answered by Vikram M. • Biology tutor
5169 Views