Question 23M.3.HL.TZ1.7
| Date | May 2023 | Marks available | [Maximum mark: 10] | Reference code | 23M.3.HL.TZ1.7 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Annotate, Describe, Determine, Predict, State, Write | Question number | 7 | Adapted from | N/A |
Lipids and carbohydrates play an essential role in the body.
State the general formula of a carbohydrate.
[1]
Cx(H2O)y ✓
Fructose is a carbohydrate. Determine the energy, in kJ, released by the respiration of 10.5 g of fructose, C6H12O6.
Enthalpy of () of fructose = −2810 kJ mol−1
[2]
«n=10.5 g/180.18 g mol−1=» 0.0583 «mol» ✓
«0.0583 mol × 2810 kJ mol−1 =» 164 «kJ» ✓
Award [2] for correct final answer.
Award [1 max] for –164 «kJ».
Glucose, an isomer of fructose, exists as two isomeric ring forms. Annotate the diagram below to complete the structure of β-glucose. Use section 34 of the data booklet.
[1]
Entire structure must be correct to score the mark.
Ignore incorrect connectivity.
Cellulose is a polymer of β-glucose. Describe the importance of cellulose in the human diet.
[1]
«provides dietary» fibre/roughage ✓
Accept prevents constipation, etc.
Lipids and carbohydrates both release energy in the body.
Write balanced equations for the complete oxidation of fructose, C6H12O6, and the triglyceride tristearin, C57H110O6.
C6H12O6: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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C57H110O6: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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[2]
C6H12O6 + 6O2 → 6CO2 + 6H2O ✓
C57H110O6 + 81.5O2 → 57CO2 + 55H2O
OR
2C57H110O6 + 163O2 →114CO2 + 110H2O ✓
Predict, giving one reason, whether 10.5 g of the triglyceride tristearin would release more or less energy than 10.5 g of fructose when completely oxidized.
[1]
more AND contains less oxygen/contains more carbon/more reduced ✓
Describe the chemical composition of phospholipids and their function in the body, other than as energy storage.
Chemical composition: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Function: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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[2]
Chemical composition:
glycerol AND «two» fatty acids AND «one» phosphate ✓
Function:
cell/plasma membrane ✓
Accept suitable diagram for M1.
Do not accept "hydrophilic head and hydrophobic tail" for M1.
Accept insulation or lipid transport for M2.
Do not accept cell wall for cell membrane.