AQA
A-Level
BIOLOGY
3.1 | Biological Molecules
1.7 | Water
Time allowed
20 minutes
QUESTION PAPER
Score Percentage
/17 %
4.1 | CELL BIOLOGY | QUESTION PAPER 1 1
, Read the following passage.
Straw consists of three main organic substances – cellulose, hemicellulose and lignin.
Cellulose molecules form chains which pack together into fibres. Hemicellulose is a
small
molecule formed mainly from five-carbon (pentose) sugar monomers. It acts as a
cement
holding cellulose fibres together. Like hemicellulose, lignin is a polymer, but it is not a
5 carbohydrate. It covers the cellulose in the cell wall and supplies additional strength. In
addition to these three substances, there are small amounts of other biologically
important
polymers present.
The other main component of straw is water. Water content is variable but may be determined
by heating a known mass of straw at between 80 and 90°C until it reaches a constant
mass.
A-Level
BIOLOGY
3.1 | Biological Molecules
1.7 | Water
Time allowed
20 minutes
QUESTION PAPER
Score Percentage
/17 %
4.1 | CELL BIOLOGY | QUESTION PAPER 1 1
, Read the following passage.
Straw consists of three main organic substances – cellulose, hemicellulose and lignin.
Cellulose molecules form chains which pack together into fibres. Hemicellulose is a
small
molecule formed mainly from five-carbon (pentose) sugar monomers. It acts as a
cement
holding cellulose fibres together. Like hemicellulose, lignin is a polymer, but it is not a
5 carbohydrate. It covers the cellulose in the cell wall and supplies additional strength. In
addition to these three substances, there are small amounts of other biologically
important
polymers present.
The other main component of straw is water. Water content is variable but may be determined
by heating a known mass of straw at between 80 and 90°C until it reaches a constant
mass.
