Sweet potatoes contain nutrients, including starch, vitamin C and proteins - Scottish Highers Chemistry - Question 6 - 2022
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 - 2022
Step 1
State what is meant by the term enzyme.
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Answer
An enzyme is a biological catalyst that speeds up 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 is the bond formed between the carboxyl group ( ext{-COOH}) of one amino acid and the amino group ( ext{-NH2}) of another, resulting in the release of a water molecule.
Step 3
Draw a structural formula for one of the amino acids used to form this section of protein.
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A structural formula for an amino acid (e.g., alanine) can be represented as:
H O
| ||
H2N-C-C-OH
| \
H R
where R represents a variable side chain.
Step 4
State what is meant by the term essential amino acid.
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An essential amino acid is an amino acid that cannot be synthesized by the human body and must therefore 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 type of reaction that takes place when amino acids join to form proteins is called condensation polymerization.
Step 6
Explain fully what happens to the enzyme structure to cause this reduction in activity.
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Answer
As sweet potatoes are cooked, the high temperatures cause the catalase enzyme to become denatured. This structural change alters the shape of the active site, decreasing its ability to bind with hydrogen peroxide and reducing its catalytic activity.
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 diagram should depict a setup including a reaction flask containing sweet potato and hydrogen peroxide, connected to a graduated syringe or gas collection tube to measure the oxygen produced. Labels should include 'hydrogen peroxide solution', 'sweet potato', and 'measuring cylinder'.
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 that can lead to the degradation of food quality and rancidity, preserving both flavor and nutritional value.
Step 9
Explain fully why vitamin C is soluble in water.
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Vitamin C is soluble in water due to its polar hydroxyl groups (–OH) which can form hydrogen bonds with water molecules, enhancing its ability to dissolve in aqueous environments.
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 mass of white potato that could produce a toxic dose:
Given:
Toxic dose = 3 mg per kg of body weight
Body weight = 65 kg
Total toxic dose = 3 mg/kg × 65 kg = 195 mg
A white potato contains 0.2 mg of solanine per g:
Let x be the mass of potato in grams.
0.2 mg/g × x g = 195 mg
Solving for x:
x = 195 mg / 0.2 mg/g = 975 g
Therefore, a mass of 975 g of white potato could produce a toxic dose.
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