The diagram shows two biological molecules.
Identify, with a reason, the diagram that contains a lipid.
The diagram below shows a ribose monosaccharide.
Sketch a molecular diagram of deoxyribose.
List two of the chemical groups found in a generalised amino acid.
Identify, with a reason, the diagram that shows the structure of a saturated fatty acid.
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List two properties of starch that make it an effective storage polysaccharide.
List two properties of cellulose that make it an effective structural polysaccharide.
Glycogen has a highly branched structure, which makes it ideal as a storage molecule in animal cells.
Describe how the branched structure of glycogen makes it an ideal energy storage compound in animals.
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Describe the composition of a triglyceride molecule.
The diagram shows a fatty acid.
(i) Identify the type of fatty acid shown in the diagram.
[1]
(ii) Give a reason for your answer to part (i).
[1]
The diagram shows a different fatty acid.
Describe and explain the properties of a lipid containing many of this type of fatty acid.
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Define the term hydrophilic.
Describe the chemical properties of carbon that allow it to form many different types of molecules.
List three groups of carbon compounds upon which living organisms are based.
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The table below contains statements that could apply to three polysaccharides.
Identify, using a tick (✓), the statements that apply to each polysaccharide.
Statement | Glycogen | Cellulose | Starch |
Branched molecule |
|
|
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Contains α-glucose |
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Hydrogen bonds between parallel chains |
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Explain how three features of starch aid its role as a storage substance.
1 markTwo molecules of a disaccharide are condensed together to form a larger sugar molecule. The chemical formula of the disaccharide is C12H22O11.
Deduce the chemical formula of the resulting larger sugar molecule.
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Sucrose is formed from monosaccharides X and Y.
The diagram below shows the structure of sucrose and monosaccharide Y.
Draw and identify monosaccharide X.
The monosaccharides fructose and glucose have the same molecular formula, C6H12O6, but different chemical structures. This give them different properties, for example fructose tastes sweeter than glucose.
Suggest one advantage of this difference to the food industry.
Molecular analysis was carried out using various laboratory techniques to distinguish between samples of three different polysaccharides. The three polysaccharides were:
Amylopectin: a branched form of starch
Amylose: a mostly unbranched, helical form of starch
Glycogen
The results are shown in the table below.
Sample | Branches per molecule | Speed of hydrolysis / arbitrary units |
A | 87 | 35 |
B | 1467 | 80 |
C | 1780 | 98 |
Deduce which of the three polysaccharides is present in each sample.
Glycogen is used as a short-term energy storage molecule.
Explain the benefits of using glycogen as an energy store.
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The diagram below shows an incomplete triglyceride molecule.
The fatty acid chain missing from carbon 1 of glycerol is monounsaturated.
State what it means for a fatty acid chain to be monounsaturated.
2 marksTrans-fats are unsaturated fatty acids that behave more like saturated fatty acids.
The table shows data from 1960 and 2000 on dietary trans-fat intake in men aged 70 years and over, and on deaths from cardiovascular disease in a Western European country.
Year | Dietary energy from trans-fats / % | Deaths from cardiovascular disease in that year |
1960 | 7 | 20 185 |
2000 | 1 | 15 542 |
Calculate the percentage decrease in numbers of deaths from cardiovascular disease between 1960 and 2000.
Forensic investigations of some patients who had died from cardiovascular disease revealed that fatty deposits in their arteries contained high concentrations of trans-fats.
Explain why this finding does not prove that trans-fats cause cardiovascular disease.
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Explain the ability of oestradiol to pass through the phospholipid bilayer.
Explain how structure relates to function in carbohydrates and lipids.
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The following diagram shows the structure of a polysaccharide found in plant cells.
(i) Identify the polysaccharide pictured in the diagram.
[1]
(ii) Explain your answer to (i).
[1]
Molecular visualisation software such as Jmol can be used to depict biological molecules.
In the Jmol visualisation, black atoms are carbon, grey atoms are oxygen and white atoms are hydrogen.
Identify the type of molecule shown in this Jmol visualisation.
2 marksThree molecules of a monosaccharide are joined to produce a trisaccharide.
The molecular formula of the original monosaccharide is C5H10O5.
Deduce the formula of the resulting trisaccharide.
2 marksA disaccharide has the formula C12H22O11. It is made up of two identical monosaccharides.
Deduce the formula of the monosaccharides from which the disaccharide is formed.
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Compare and contrast glycogen and starch.
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