Qualification > Sciences

ALL CIE BIOLOGY DOUBTS HERE !!!

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Dania:

--- Quote from: Deadly_king on November 15, 2010, 05:03:48 pm ---The sucrose id first loaded into the companion cell by active transport, using a protein molecule in the cell membrane as carrier or transporter. The latter pump out hydrogen ions actively. This creates a high concentration of H+ ions outside the companion cell.

Now the H+ ions diffuse back into the companion cell using a protein carrier down its concentration gradient. The latter move sucrose at the same time as the H+ ions. But the sucrose moves against its concentration gradient.

In other words, sucrose is being co-transported along with the H+ ions. The sucrose moves into the adjacent sieve tube elements through the plasmodesmata.

Hope it helps :)

--- End quote ---

Thank You! That's just what I need.

Dania:
How come no one has doubts about tomorrow's exam? I'm surprised.

Deadly_king:

--- Quote from: Dania on November 15, 2010, 08:42:39 pm ---How come no one has doubts about tomorrow's exam? I'm surprised.

--- End quote ---

I think there are not many members sitting for Biology this year. :-[

elemis:

--- Quote from: Deadly_king on November 16, 2010, 11:33:53 am ---I think there are not many members sitting for Biology this year. :-[

--- End quote ---

Not many answer in the winter session.

Arthur Bon Zavi:

--- Quote from: Ari Ben Canaan on November 16, 2010, 01:58:05 pm ---Not many answer in the winter session.

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That's a good fact.

Candidates appearing in May/June sessions are far more than candidates appearing in October/November session.

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