Please help with As biology question

Heres the question it has two parts:
a) Galactose and glucose are absorbed by epithelial cells lining the small intestine but some other monosaccharides are not. Use your knowledge of active transport to explain this differance
b)Diarrhoea involves the production of large amounts of watery faeces. Explain the link between the presence of lactose in the intestine and diarrhoea.

Thanks in advance for any help!

Reply 1

Molsaka G

1

doormat

Heres the question it has two parts:
a) Galactose and glucose are absorbed by epithelial cells lining the small intestine but some other monosaccharides are not. Use your knowledge of active transport to explain this differance
b)Diarrhoea involves the production of large amounts of watery faeces. Explain the link between the presence of lactose in the intestine and diarrhoea.

Thanks in advance for any help!

Right, for a) I think that its because there are many glucose and galactose carrier proteins (remember active transport requires these) in the epithelial lining and so they can be absorped. But for the other monosaccharides, there are very few or none, and so they cannot be absorped.

I'll let someone more knowledgeable answer b) :p:

(wasn't on our syllabus I don't think)

Hope that helps :smile:

.

Reply 2

Ribbons

12

b)Diarrhoea involves the production of large amounts of watery faeces. Explain the link between the presence of lactose in the intestine and diarrhoea.

im not at all sure, but this is what i think:

In diarrhoea basically what happens is that the uptake of water and nutrients by the epithelial cells is reduced--very little is absorbed. Watery faeces confirm that, as the water that shoudlve been absorbed is not, and is passed out of the body. The uptake of other nutrients or molecules is also affected. The lactose which would have been absorbed by the cells (or taken in by active transport to be more accurate) and broken down to glucose and galactose, isnt taken up and therefore you'll find more of it in the lumen of the intestine.

Reply 3

Flame

For b:

The enzyme lactase (Which digests lactose) is found mainly in the small intestine. Diarrhoea tends to inhibit the production of this enzyme by damaging the intestine walls. So there's lots of undigested lactose lying around. That's why one of the ways to treat diarrhoea is to reduce lactose intake, because dairrhoea makes the person temporarily lactose intolerant.

Also, people who are lactose intolerant anyway get something called lactose diarrhoea when they drink milk. They get gas and all sorts of nasty gastric rumblings, and the body tries to get rid of this stuff by flushing it out with plenty of water, so the victims have to rush to the bathroom often. ^_^ Isn't that lovely?

Please help with As biology question

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