What is the usual source of cholera infection?

The usual source is drinking water or food contaminated with faeces from an infected person or a carrier, since humans are the main reservoir.

Which tissue does Vibrio cholerae affect?

It colonises the epithelium lining the small intestine, without invading the cells or entering the blood.

Why is oral rehydration solution given with glucose in it as well as salts?

Glucose is absorbed into the epithelial cells together with sodium ions by a co-transport carrier, and that movement of solute draws water back across the gut wall by osmosis.

How is cholera prevented at the level of a whole community?

Cholera is prevented by supplying treated drinking water, by treating and separating sewage from the water supply, and by hygiene measures such as hand washing and thorough cooking of shellfish.

Eduqas A-Level Biology A400QS

Biological Molecules

Topic overview Inorganic ions and the properties of water Monosaccharides and disaccharides Polysaccharides, storage and structure Lipids, triglycerides and phospholipids Amino acids and protein structure Condensation, hydrolysis and the food tests

Cell Structure and Organisation

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Cell Membranes and Transport

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Enzymes

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Immunology and Disease: Disease and Its TransmissionImmunology

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Immunology and Disease: AntibioticsImmunology

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Immunology and Disease: The Immune ResponseImmunology

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Human Musculoskeletal Anatomy: Skeletal TissuesMusculoskeletal

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Neurobiology and Behaviour: The BrainNeurobiology

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Neurobiology and Behaviour: NeuroscienceNeurobiology

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Neurobiology and Behaviour: BehaviourNeurobiology

Topic overview Innate behaviour: escape reflexes, kineses and taxes Habituation and imprinting Classical and operant conditioning Primate societies and the costs and benefits of group living Insect castes, dominance hierarchies, territory and courtship

Immunology and Disease: Disease and Its Transmission

Cholera and tuberculosis

3 things to know
Component 3

Overview

Usual source of cholera infection, how the cholera toxin produces severe watery diarrhoea and two species of bacteria that cause tuberculosis in humans.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain how the cholera toxin produces severe watery diarrhoea.

Key term

Why must tuberculosis be treated with a combination of antibiotics for six months or more?

Key term

Name the organism that causes cholera and state what type of organism it is.

Questions from this subtopic

Each one with the model answer underneath.

1
Name the organism that causes cholera and state what type of organism it is.
Model answer
Cholera is caused by Vibrio cholerae, a comma-shaped Gram negative bacterium.
2
What is the usual source of cholera infection?
Model answer
The usual source is drinking water or food contaminated with faeces from an infected person or a carrier, since humans are the main reservoir.
3
Which tissue does Vibrio cholerae affect?
Model answer
It colonises the epithelium lining the small intestine, without invading the cells or entering the blood.
4
Explain how the cholera toxin produces severe watery diarrhoea.
Model answer
The toxin binds to the intestinal epithelial cells and locks their chloride ion channels open, so chloride ions flood into the lumen, sodium ions and water follow down the resulting gradients, and litres of fluid are lost from the tissues.
5
Why is oral rehydration solution given with glucose in it as well as salts?
Model answer
Glucose is absorbed into the epithelial cells together with sodium ions by a co-transport carrier, and that movement of solute draws water back across the gut wall by osmosis.
6
How is cholera prevented at the level of a whole community?
Model answer
Cholera is prevented by supplying treated drinking water, by treating and separating sewage from the water supply, and by hygiene measures such as hand washing and thorough cooking of shellfish.

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