required practicals

Question 1

What is the practicle for comparing energy in foods? (bread and pasta)

Answer 1

• Burn 1g of both foods and hold them under a boiling tube filled with water.
• Find the tempereture change of the water by the time the whole 1g is burnt.

Question 2

How do you test for starch, glucose and protien in foods?

Answer 2

• For starch, add iodine solution to the food and if starch is present it will go from brown to blue/black.
• For glucose, add benedicts solution to the food and if glucose is present it will go from blue to green, yellow, orange or red depending on the amount of glucose.
• For protien, add biurets solution to the food and if protien is present it will go from blue to lilac/purple.

Question 3

How would you investigate factors affecting enzyme activity?

Answer 3

• Mix 1% starch solution and iodine. Ina seperate tube measure some 10% amylase solution.
• Put them both in the 20 degrees water bath for 3 minutes. Remove them and mix both together.
• Record the colour every minute for 5 minutes after adding the solution.
• Repeat this for higher temperetures.

Question 4

How would you represent the model gut in a practical?

Answer 4

• Visking tubing (small intestine) would contain starch and amylase solution and it would be surrounded by water (blood).
• The amylase breaks down the starch into glucose (smaller particles) and the glucose will pass through the semi-permeable membrane and into the water.

Question 5

What do different parts of the ‘bell jar model of breathing’ represent?

Answer 5

Bell jar- Ribs (protects the lungs)
Balloon- Lungs (Expand and decrease as air moves in and out)
Rubber sheet- diaphragm (moves down when air goes in and up when air goes out)
Tube in ballon- Trachea