Question
Draw a molecular diagram of alpha-D-glucose. [3]
▶️Answer/Explanation
Ans
a.hexagonal ring structure with O at one point (between C1 and C5);
b.correct orientation of OH groups (on carbons 1 to 4); Hydrogens not required
c.CH2OH group shown on fifth carbon with correct orientation;
OR
d.6 carbon chain with oxygen on first C;
e.H and OH groups correctly orientated;
or
Question
State one disaccharide and the two monomers from which it can be synthesized.
Disaccharide:
1:
Monomers:
1:
and 2:
Discuss the roles of the enzymes secreted by the pancreas during digestion.
Compare and contrast cis-fatty acids and trans-fatty acids.
▶️Answer/Explanation
Markscheme
a. disaccharide name
eg: lactose, glucose and galactose
b. both monomers that make up mpa
eg: maltose, glucose and glucose
eg: sucrose, glucose and fructose
a. amylase breaks down/catalyzes/hydrolyses starch to maltose
b. lipase breaks down/catalyzes/hydrolyses fats to fatty acids and glycerol
c. proteases/peptidases break down/catalyze/hydrolyze proteins into smaller
polypeptides/dipeptides/amino acids
Award [2] if all three enzymes and substrates named correctly and one further mark for all three products named
correctly.
Allow specific enzymes
a. both are unsaturated fatty acids
OR
both have two carbon atoms joined by a double bond
b. in cis-fatty acids the two H atoms are on the same side while in trans-fatty acids they are on opposite sides
OR
cis-fatty acids are healthier than trans-fatty acids
OR
cis-fatty acids have a lower boiling/melting point than trans
OR
cis-fatty acids have a kink «in the chain» but trans do not
Accept answer in an annotated diagram
Question
Define metabolism.
Identify the following processes as either anabolism or catabolism by placing a tick (√) in the correct box.
Describe cell respiration in terms of metabolism.
▶️Answer/Explanation
Markscheme
(the web of all) the enzyme-catalyzed reactions in a cell/organism
OR
the totality of an organism’s chemical reactions (consisting of catabolic and anabolic pathways which manage the material and energy resources of the cell)
a. «cell respiration is metabolism because» enzymes control the reactions
b. energy is released from complex molecules «to make ATP»
c. respiration is catabolic (metabolism)
OR
complex molecules become simpler
OR
C6H12O6 to CO2 + H2O
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