Transport Across Membranes - 6 Marker HELP

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gandalfhan
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#1
Report Thread starter 1 year ago
#1
So I got this question asking

“ The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how”

And me confused as usual outlined the whole process of absorption of glucose and I’m not sure if I will get any marks. This is what I said

“Microvilli provides large surface area for transport. Firstly, absorption of glucose starts when sodium ions are actively transported out of epithelial cells in the ileum into the bloodstream via sodium-potassium pump. This creates a concentration gradient- there is greater concentration of sodium ions in the lumen than inside the cell. Then, sodium is transported by sodium-glucose co-transporter protein into the epithelial cells down the concentration gradient. Also, glucose is attached to this protein and is transported against concentration gradient. There is a lot of mitochondria which provides ATP for active transport of glucose. Then glucose diffuses out of epithelial cells via facilitated diffusion using carrier protein that releases glucose into bloodstream”.

But the mark scheme says this and I’m not sure:

“ 1. Microvilli provide a large / increased surface area;
2. Many mitochondria produce ATP / release or provide energy (for active transport);
3. Carrier proteins for active transport;
4. Channel / carrier proteins for facilitated diffusion;
5. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6. Membrane-bound enzymes digest disaccharides / produce glucose;
1. Reject villi on epithelial cells
1. Accept brush border
2. Accept large SA:vol ratio
3. Need idea of “lots”
4. Reject: energy produced
5. Accept Na+K+ pump
6. Neutral: Channel proteins
7. Accept named example”

Can anyone help me and tell me if I would gain marks if I said that?
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medscorer2020
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(Original post by gandalfhan)
So I got this question asking

“ The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how”

And me confused as usual outlined the whole process of absorption of glucose and I’m not sure if I will get any marks. This is what I said

“Microvilli provides large surface area for transport. Firstly, absorption of glucose starts when sodium ions are actively transported out of epithelial cells in the ileum into the bloodstream via sodium-potassium pump. This creates a concentration gradient- there is greater concentration of sodium ions in the lumen than inside the cell. Then, sodium is transported by sodium-glucose co-transporter protein into the epithelial cells down the concentration gradient. Also, glucose is attached to this protein and is transported against concentration gradient. There is a lot of mitochondria which provides ATP for active transport of glucose. Then glucose diffuses out of epithelial cells via facilitated diffusion using carrier protein that releases glucose into bloodstream”.

But the mark scheme says this and I’m not sure:

“ 1. Microvilli provide a large / increased surface area;
2. Many mitochondria produce ATP / release or provide energy (for active transport);
3. Carrier proteins for active transport;
4. Channel / carrier proteins for facilitated diffusion;
5. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6. Membrane-bound enzymes digest disaccharides / produce glucose;
1. Reject villi on epithelial cells
1. Accept brush border
2. Accept large SA:vol ratio
3. Need idea of “lots”
4. Reject: energy produced
5. Accept Na+K+ pump
6. Neutral: Channel proteins
7. Accept named example”

Can anyone help me and tell me if I would gain marks if I said that?
“Microvilli provides large surface area for transport. Firstly, absorption of glucose starts when sodium ions are actively transported out of epithelial cells in the ileum into the bloodstream via sodium-potassium pump. This creates a concentration gradient- there is greater concentration of sodium ions in the lumen than inside the cell. Then, sodium is transported by sodium-glucose co-transporter protein into the epithelial cells down the concentration gradient. Also, glucose is attached to this protein and is transported against concentration gradient. There is a lot of mitochondria which provides ATP for active transport of glucose. Then glucose diffuses out of epithelial cells via facilitated diffusion using carrier protein that releases glucose into bloodstream”.

You are missing point 6 so I would give you 5/6. But the second bold phrase should ideally be to do with carrier proteins for active transport rather than sodium potassium pump
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Baby_Mama
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#3
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#3
(Original post by gandalfhan)
So I got this question asking

“ The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how”

And me confused as usual outlined the whole process of absorption of glucose and I’m not sure if I will get any marks. This is what I said

“Microvilli provides large surface area for transport. Firstly, absorption of glucose starts when sodium ions are actively transported out of epithelial cells in the ileum into the bloodstream via sodium-potassium pump. This creates a concentration gradient- there is greater concentration of sodium ions in the lumen than inside the cell. Then, sodium is transported by sodium-glucose co-transporter protein into the epithelial cells down the concentration gradient. Also, glucose is attached to this protein and is transported against concentration gradient. There is a lot of mitochondria which provides ATP for active transport of glucose. Then glucose diffuses out of epithelial cells via facilitated diffusion using carrier protein that releases glucose into bloodstream”.

But the mark scheme says this and I’m not sure:

“ 1. Microvilli provide a large / increased surface area;
2. Many mitochondria produce ATP / release or provide energy (for active transport);
3. Carrier proteins for active transport;
4. Channel / carrier proteins for facilitated diffusion;
5. Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6. Membrane-bound enzymes digest disaccharides / produce glucose;
1. Reject villi on epithelial cells
1. Accept brush border
2. Accept large SA:vol ratio
3. Need idea of “lots”
4. Reject: energy produced
5. Accept Na+K+ pump
6. Neutral: Channel proteins
7. Accept named example”

Can anyone help me and tell me if I would gain marks if I said that?
Yh i would give 5 marks for your answer. Is this OCR biology by the way?
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gandalfhan
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Report Thread starter 1 year ago
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(Original post by medscorer2020)
“Microvilli provides large surface area for transport. Firstly, absorption of glucose starts when sodium ions are actively transported out of epithelial cells in the ileum into the bloodstream via sodium-potassium pump. This creates a concentration gradient- there is greater concentration of sodium ions in the lumen than inside the cell. Then, sodium is transported by sodium-glucose co-transporter protein into the epithelial cells down the concentration gradient. Also, glucose is attached to this protein and is transported against concentration gradient. There is a lot of mitochondria which provides ATP for active transport of glucose. Then glucose diffuses out of epithelial cells via facilitated diffusion using carrier protein that releases glucose into bloodstream”.

You are missing point 6 so I would give you 5/6. But the second bold phrase should ideally be to do with carrier proteins for active transport rather than sodium potassium pump
Thank you so much!
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gandalfhan
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#5
Report Thread starter 1 year ago
#5
(Original post by Baby_Mama)
Yh i would give 5 marks for your answer. Is this OCR biology by the way?
Thank you and it is AQA Biology.
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