Biological Molecules TYS (updated 2023)

Benedict's solution is used to test for the presence of reducing sugars.

Which colour change shows the presence of a reducing sugar?

• blue to orange-red

• blue to purple

• orange-red to blue

• purple to blue

What are the basic units of proteins?

• amino acids

• fatty acids

• glucose

• glycerol

Which chemical is used to test for the presence of protein in a food sample?

• Benedict's solution

• biuret solution

• ethanol

• iodine in potassium iodide solution

A sample of food contains reducing sugar and fat. Which food test results show this?

• Biuret solution turns purple and iodine solution turns blue-black.

• Brick red precipitate formed with Benedict's solution and biuret solution turns purple.

• Brick red precipitate formed with Benedict's solution and white emulsion formed with ethanol and water.

• Iodine solution turns blue-black and white emulsion formed with ethanol and water.

A scientist carries out four different tests on an unknown sample of food. The sample is a clear liquid.

Which food group is not in the sample?

• fat

• protein

• reducing sugar

• starch

What are lipids synthesized from?

• amino aicds and fatty acids

• fatty acids and glycerol

• glucose and amino acids

• glycerol and glucose

Which of the following chemicals detects the presence of reducing sugars in a food sample?

• Benedict's solution

• biuret reagent

• ethanol

• iodine in potassium iodide solution

BONUS: Ms Ang spends a decent amount of time weightlifting.

What supplement should she take to enhance her performance?

• glucose

• lactose

• fat

• protein