AQA
A-Level
BIOLOGY
3.3 | Organisms Excange Substances
3.6 | Mass Transport in Plants
Time allowed
38 minutes
QUESTION PAPER
Score Percentage
/32 %
4.1 | CELL BIOLOGY | QUESTION PAPER 1 1
, 1. (a) Describe the mass flow hypothesis for the mechanism of translocation in plants.
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(Extra space) ................................................................................................
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(4)
Scientists measured translocation in the phloem of trees. They used carbon dioxide
labelled with radioactive 14C.
They put a large, clear plastic bag over the leaves and branches of each tree and
added 14CO2. The main trunk of the tree was not in the plastic bag.
At regular intervals after adding the 14CO2 to the bag, the scientists measured the
amount of 14CO2 released from the top and bottom of the main trunk of the tree. On
the surface of the trunk of these trees, there are pores for gas exchange.
A-Level
BIOLOGY
3.3 | Organisms Excange Substances
3.6 | Mass Transport in Plants
Time allowed
38 minutes
QUESTION PAPER
Score Percentage
/32 %
4.1 | CELL BIOLOGY | QUESTION PAPER 1 1
, 1. (a) Describe the mass flow hypothesis for the mechanism of translocation in plants.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(Extra space) ................................................................................................
........................................................................................................................
(4)
Scientists measured translocation in the phloem of trees. They used carbon dioxide
labelled with radioactive 14C.
They put a large, clear plastic bag over the leaves and branches of each tree and
added 14CO2. The main trunk of the tree was not in the plastic bag.
At regular intervals after adding the 14CO2 to the bag, the scientists measured the
amount of 14CO2 released from the top and bottom of the main trunk of the tree. On
the surface of the trunk of these trees, there are pores for gas exchange.
