3 marks
Table 1
| Ā hydrogen | Ā |
| Ā water | Ā |
| Ā sulfur | Ā |
| Ā silicon | Ā |
| Ā titanium | Ā |
| Ā nitrogen | Ā |
| Ā carbon | Ā |
Place a tick (ā) in the boxes next to the chemical elements that are found naturally in living organisms.
1 mark1 markName the molecule that, in certain fats, binds to three fatty acid molecules.
Did this page help you?
1 markA student processed a sample of food into an aqueous solution and tested it with a test solution. The test solution changed from blue to violet.
Name the solution used in this test.
1 markState the food group that the experiment in part (a) showed a positive result for.
1 markA sample of butter was shaken with ethanol, followed by an equal volume of cold water.
Predict the appearance of the mixture after the addition of water.
2 marksA sample of freshly-squeezed orange juice was mixed with DCPIP solution.
Predict the result of this food test, and explain your prediction.Ā
Did this page help you?
2 marksTable 1 contains some statements about biological molecules.
Table 1
| Ā | Correct? (ā) |
| Ā They contain carbon, hydrogen and oxygen only | Ā |
| Ā All are sugars | Ā |
| Ā They are all formed from long chains of glucose moleculesĀ | Ā |
| Ā They are the principal energy source in the animal diet | Ā |
| Ā They include starch, cellulose and triglycerides | Ā |
| Ā They form solids at room temperature but melt into liquids when warmer | Ā |
| Ā The sequence of the building blocks determines their function | Ā |
Place ticks (ā) in Table 1 to indicate statements that apply to carbohydrates.
3 marksCompare the chemical elements found in carbohydrates and proteins.
Did this page help you?
2 marksFig. 1 shows the components of fats and oils as shapes.
Using these shapes, sketch the appearance of a triglyceride molecule that would be found in fats and oils.
Fig. 1
3 marksTable 1 contains some statements about the fate of proteins in an animal's body.
Table 1
| Ā A.Ā | Ā Protein undergoes chemical digestion |
| B. | Ā Amino acids circulate in the blood |
| C. | Ā Food is ingested |
| D. | Ā Peptides are put together in protein synthesis |
| E. | Ā Peptides are synthesised |
Place these events into a logical chronological order.
| 1st | ā | 2nd | ā | 3rd | ā | 4th | ā | 5th |
| Ā | Ā | Ā | Ā | Ā | Ā | Ā | Ā | Ā |
2 marksDescribe the test that would be used to show a positive result for the presence of protein in a sample of food.
Did this page help you?
2 marks
Table 1
| test number | contents |
| 1 | Ā Water |
| 2 | Ā Potato juice |
| 3 | Ā Dilute orange juice |
| 4 | Ā Glucose sports drink e.g. Lucozadeā¢ |
The results are shown in Fig.1Ā
Fig. 1
The Benedict's test is referred to as being semi-quantitative.
Use the information provided in Table 1 and Fig. 1 to suggest what the term 'semi-quantitative' means.Ā
2 marksExplain the purpose of the test tube containing just water in the experiment shown in Fig. 1.
2 marksExplain why the test for lipids is known as an emulsion test.
3 marks
Table 2
| food sample | iodine test result |
| Bagel | Ā |
| Eggs | Ā |
| Fish | Ā |
| Rice | Ā |
| Grapefruit | Ā |
Did this page help you?