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A2 Biology | Post your doubts here

O

omair tahir

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Explain how the collecting ducts in the kidneys may reduce the loss of water frm the body

Collecting duct runs down into the the medulla where solute concentration of the tissue fluid is very high, with a very low water potential. Water therefore moves out the collecting duct, by osmosis, until the water potential of urine is same as the water potential of the tissue fluid in the medulla, which may be much greater than the water potential of the blood. The degree to which this happens is controlled by ADH. It acts on the plasma membrane of the cells making up the walls of the CT in kidneys, this increases the permeability of membrane to water by increasing number the water permeable channels in the membrane.

Am i writing it correctly plx help ?
 
angelgirl:)

angelgirl:)

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omair tahir said:
Explain how the collecting ducts in the kidneys may reduce the loss of water frm the body

Collecting duct runs down into the the medulla where solute concentration of the tissue fluid is very high, with a very low water potential. Water therefore moves out the collecting duct, by osmosis, until the water potential of urine is same as the water potential of the tissue fluid in the medulla, which may be much greater than the water potential of the blood. The degree to which this happens is controlled by ADH. It acts on the plasma membrane of the cells making up the walls of the CD in kidneys, this increases the permeability of membrane to water by increasing number of the water permeable channels in the membrane.

Am i writing it correctly plx help ?
Click to expand...
yes u do...
 
Paradoxical

Paradoxical

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omair tahir said:
Explain how the collecting ducts in the kidneys may reduce the loss of water frm the body

Collecting duct runs down into the the medulla where solute concentration of the tissue fluid is very high, with a very low water potential. Water therefore moves out the collecting duct, by osmosis, until the water potential of urine is same as the water potential of the tissue fluid in the medulla, which may be much greater than the water potential of the blood. The degree to which this happens is controlled by ADH. It acts on the plasma membrane of the cells making up the walls of the CT in kidneys, this increases the permeability of membrane to water by increasing number the water permeable channels in the membrane.

Am i writing it correctly plx help ?
Click to expand...

Yep, it's correct. If the blood water content is low then osmoreceptors in the hypothalamus cause ADH to be secreted. The ADH binds to the plasma membrane of the collecting duct and activates an enzyme inside the cell. This activation of this enzyme leads to vesicles surrounded by pieces of membrane full of water-permeable channels to move to the membrane and fuse with it. Thus adding many water-permeable channels to the membrane of the collecting duct. Water is now free to move out of the duct and into the tissue fluid, and it does this because this region of the kidney contains a high concentration of salts.
 
angelgirl:)

angelgirl:)

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omair tahir said: ↑
Explain how the collecting ducts in the kidneys may reduce the loss of water frm the body

Collecting duct runs down into the the medulla where solute concentration of the tissue fluid is very high, with a very low water potential. Water therefore moves out the collecting duct, by osmosis, until the water potential of urine is same as the water potential of the tissue fluid in the medulla, which may be much greater than the water potential of the blood. The degree to which this happens is controlled by ADH. It acts on the plasma membrane of the cells making up the walls of the CT in kidneys, this increases the permeability of membrane to water by increasing number the water permeable channels in the membrane.

Am i writing it correctly plx help ?​
Yep, it's correct. If the blood water content is low then osmoreceptors in the hypothalamus cause ADH to be secreted. The ADH binds to the plasma membrane of the collecting duct and activates an enzyme inside the cell. This activation of this enzyme leads to vesicles surrounded by pieces of membrane full of water-permeable channels to move to the membrane and fuse with it. Thus adding many water-permeable channels to the membrane of the collecting duct. Water is now free to move out of the duct and into the tissue fluid, and it does this because this region of the kidney contains a high concentration of salts.

is it moving inthe tissue fluid or is reabsorbed by the Vasa recta that is the capellaries around the collecting duck...as the conc...in the blood is low​
​
​
 
user

user

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Aoa wr wb

ms says for the function of DNA ligase
· seals nicks in sugar-phosphate backbone ;
· forms rDNA ;
· by adding phosphate group ;
i dont get the last point?
 
angelgirl:)

angelgirl:)

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user said:
Aoa wr wb

ms says for the function of DNA ligase
· seals nicks in sugar-phosphate backbone ;
· forms rDNA ;
· by adding phosphate group ;
i dont get the last point?
Click to expand...
means while plasmid and cDNA gene r mixed then legase is used to combine their suger posphate backbone to make recombinant DNA (rDNA)
 
user

user

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confused_soul

Explain why promoters need to be transferred into the recipient bacteria together with the genes.
Only the better candidates were able to show that promoters were needed to ensure that the genes
were “switched on” in order to produce the correct protein. It was rare, however, to see a reference
to the fact that a eukaryotic gene had been placed in a prokaryotic cell.

Disadvantages of using antibiotic resistance as markers in gene technology:

1. risk spread of resistance to other bacteria ;
2. spread of resistance makes the use of antibiotics less effective / AW ;
3. via, conjugation / transformation / uptake of plasmids ; A description
4. via, ‘phage / transduction ; A description
5. ref. R plasmid multiple resistance (MDR) / extreme resistance (XDR) ;
^last 3 ms points?
 
ousamah112

ousamah112

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How did it go??? mine went normal..it was so lengthy. plus it was more like environmental paper thn a biology one...
 
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