Question 1: Describe what happens to the starch molecules in potatoes when they are cooked. Include the term 'gelatinisation' in your answer.

Answer: When potatoes are cooked, the heat causes the starch molecules to absorb water and swell, a process called gelatinisation. This makes the potatoes softer and changes their texture.

Question 2: Explain what occurs during the Maillard reaction and how it affects the appearance and flavor of cooked meat.

Answer: The Maillard reaction occurs when amino acids and reducing sugars react under heat, causing browning. This reaction gives cooked meat a rich flavor and a browned, appealing appearance.

Question 3: Identify the chemical change that occurs when fruit is preserved with sugar and describe its effect on the fruit.

Answer: The fruit undergoes osmotic dehydration as sugar draws water out of the fruit, which prevents microbial growth and preserves the fruit, often making it sweeter and firmer.

Question 4: Describe what happens during caramelisation and how it changes the colour and taste of sugar.

Answer: Caramelisation occurs when sugar is heated to a high temperature, causing it to break down and form new compounds. This results in a golden-brown colour and a rich, sweet, toasted flavor.

Question 5: Explain the process of oxidation in food and give an example of a food that can turn brown due to oxidation.

Answer: Oxidation is a chemical reaction where food reacts with oxygen, causing changes such as browning. An example is an apple turning brown after being cut and exposed to air.

Question 6: Draw a labelled diagram of a simple chemical change that occurs when baking bread. Include key ingredients and the process involved.

Answer: A diagram showing yeast, flour, water, and heat, with labels indicating fermentation (production of carbon dioxide) and baking (starch gelatinisation and protein coagulation). The diagram should illustrate how these lead to bread rising and setting.

Question 7: Describe how heat causes the protein in eggs to change during cooking. Use scientific terms in your explanation.

Answer: When eggs are heated, the proteins denature, meaning they unfold and then coagulate, transforming from a liquid to a solid, which gives cooked eggs their firm texture.

Question 8: Identify two ways in which chemical changes in food can affect its nutritional value.

Answer: Chemical changes can reduce vitamin content through heat or oxidation, and can also alter the availability of minerals, either making them more accessible or causing them to be lost.

Question 9: Sketch a simple diagram showing the process of fermentation in bread-making. Label the key ingredients and the main chemical change involved.

Answer: A sketch depicting yeast, flour, water, with arrows indicating fermentation producing carbon dioxide. Labels should include 'Yeast ferments sugars' and 'Carbon dioxide causes dough to rise'.