Sweet potatoes contain nutrients, including starch, vitamin C and proteins - Scottish Highers Chemistry - Question 6 - 2023
Question 6
Sweet potatoes contain nutrients, including starch, vitamin C and proteins.
(a) Catalase is an enzyme contained in sweet potatoes that speeds up the breakdown of hy... show full transcript
Worked Solution & Example Answer:Sweet potatoes contain nutrients, including starch, vitamin C and proteins - Scottish Highers Chemistry - Question 6 - 2023
Step 1
State what is meant by the term enzyme.
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Answer
An enzyme is a biological catalyst that accelerates chemical reactions in the body without being consumed in the process.
Step 2
Circle a peptide link in the above structure.
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Answer
The peptide link in the structure is the bond between the carbon of the carboxyl group (C=O) of one amino acid and the nitrogen of the amino group (NH) of the next amino acid.
Step 3
Draw a structural formula for one of the amino acids used to form this section of protein.
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One possible amino acid is:
H O
| ||
H2N-C-C-H
| |
H OH
This represents serine, a standard amino acid.
Step 4
State what is meant by the term essential amino acid.
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Essential amino acids are amino acids that cannot be synthesized by the body and must be obtained through diet.
Step 5
Name the type of reaction that takes place when amino acids join to form proteins.
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The reaction that takes place is called condensation polymerization, where water is released as amino acids combine to form peptide bonds.
Step 6
Explain fully what happens to the enzyme structure to cause this reduction in activity.
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As sweet potatoes are cooked, the heat leads to the denaturation of the catalase enzyme. The enzyme's three-dimensional structure is altered, affecting the active site, and hence reducing its ability to bind to hydrogen peroxide and catalyze the reaction.
Step 7
Draw a diagram showing assembled apparatus that could be used to react hydrogen peroxide solution with sweet potato and measure the volume of oxygen produced.
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A suitable diagram would include a beaker with hydrogen peroxide, a piece of sweet potato submerged inside, a delivery tube connected to an inverted graduated cylinder filled with water to collect the gas produced. The reactants and apparatus should be clearly labeled.
Step 8
Explain why antioxidants are added to food.
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Antioxidants like vitamin C are added to food to prevent unwanted oxidation, which can lead to the degradation of food quality, including rancidity and nutritional loss.
Step 9
Explain fully why vitamin C is soluble in water.
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Vitamin C is polar due to its hydroxyl (-OH) groups, which interact favorably with water molecules, allowing it to dissolve easily in water.
Step 10
Calculate the mass of white potato that could produce a toxic dose to an adult weighing 65 kg.
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To calculate the toxic dose:
The toxic dose for a 65 kg adult is:
3 mg * 65 kg = 195 mg of solanine.
Given that a typical potato can contain 0.2 mg of solanine per gram:
Mass of potato = 195 mg / 0.2 mg/g = 975 g.
Thus, a mass of 975 g of white potato could produce a toxic dose.
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