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ALL CIE BIOLOGY DOUBTS HERE !!!

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Dania:
Does anyone have notes on this particular segment of Genetic Control?

Thanks in advance.

Dania:
Help! Anyone?

The answer is D.

Deadly_king:

--- Quote from: Dania on November 16, 2010, 05:56:43 pm ---Does anyone have notes on this particular segment of Genetic Control?

Thanks in advance.

--- End quote ---

Sickle Cell Anaemia results from a substitution of one base which in turn transform the whole amino acid from the glutamic acid to valine. More precisely an adenine has been replaced by a thymine.

So the answer is A.

I do not have the specific notes but the application booklet for Chemistry(Page 39) is very helpful. Do take a look. ;)

Click here for more details about Sickle Cell Anaemia.

Deadly_king:

--- Quote from: Dania on November 16, 2010, 10:05:44 pm ---Help! Anyone?

The answer is D.

--- End quote ---

The walls of both the alveolus and the capillary is one cell thick. Hence for gaseous exchange to occur the gas has to pass:

i) through the cell membrane of the one cell thick squamous epithelial cell of the alveoli so that it enters the cell.

ii) through the cell membrane of the same cell but in the opposite direction. The gas now leaves the cell, in other words it gets out of the alveoli.

iii) across the cell membrane of the one cell thick squamous epithelial cell of the capillary such that the gas enters the cell.

iv) across the cell membrane of the same cell but in opposite direction to get out of the cell and into the blood vessel.

v) lastly the gas needs to go through the cell membrane of the red blood cell for transport.

So in all, the gas has to pass across 5 cell membranes.

See the picture attached so that you may understand it better. ;)

Dania:

--- Quote from: Deadly_king on November 17, 2010, 05:21:21 am ---The walls of both the alveolus and the capillary is one cell thick. Hence for gaseous exchange to occur the gas has to pass:

i) through the cell membrane of the one cell thick squamous epithelial cell of the alveoli so that it enters the cell.

ii) through the cell membrane of the same cell but in the opposite direction. The gas now leaves the cell, in other words it gets out of the alveoli.

iii) across the cell membrane of the one cell thick squamous epithelial cell of the capillary such that the gas enters the cell.

iv) across the cell membrane of the same cell but in opposite direction to get out of the cell and into the blood vessel.

v) lastly the gas needs to go through the cell membrane of the red blood cell for transport.

So in all, the gas has to pass across 5 cell membranes.

See the picture attached so that you may understand it better. ;)

--- End quote ---

Thank you! Very helpful. Eid Mubarak!

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