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

Answer: When potatoes are cooked in boiling water, the starch granules absorb water and swell, a process called gelatinisation. This causes the potatoes to become soft and easier to digest.

Question 2: Explain why bread dough rises when yeast is added and heated during baking.

Answer: Yeast ferments the sugars in the dough, producing carbon dioxide gas. When heated, this gas expands, causing the dough to rise and become light and fluffy.

Question 3: Identify the chemical change that occurs when fruit is exposed to air and begins to turn brown.

Answer: The fruit undergoes oxidation, where enzymes react with oxygen, causing browning.

Question 4: Describe what happens to the proteins in meat during cooking. Include the term 'coagulation' in your explanation.

Answer: When meat is cooked, the heat causes the proteins to denature and then coagulate, which means they change from liquid to solid, making the meat firm.

Question 5: Explain why milk sours when it is left out of the fridge for too long.

Answer: Milk sours because bacteria in the milk ferment the lactose, producing lactic acid, which causes the milk to spoil.

Question 6: Draw a simple flowchart to show the process of caramelisation of sugar. Include at least three steps.

Answer: A correct flowchart would start with 'Heating sugar,' then 'Sugar melts and turns golden,' followed by 'Caramel forms,' and finally 'Flavor develops.'

Question 7: What is the chemical change that occurs when an egg is cooked? Describe the process in your own words.

Answer: When an egg is cooked, the heat causes the proteins in the egg white and yolk to denature and coagulate, turning the liquid egg into a solid.

Question 8: Identify one food item that undergoes fermentation and describe the chemical change involved.

Answer: Yogurt undergoes fermentation, where bacteria convert lactose into lactic acid, which thickens the milk and gives yogurt its tangy flavor.

Question 9: Sketch a diagram showing the process of baking a cake, including the key chemical changes involved.

Answer: A correct sketch would depict batter expanding as gases from baking powder or yeast cause it to rise, with notes indicating the coagulation of proteins and gelatinisation of starches occurring during baking.

Question 10: Explain what causes the crust of bread to turn brown during baking.

Answer: The crust turns brown due to the Maillard reaction and caramelisation, which are chemical reactions between amino acids and sugars when heated.