2025 IGCSE - Food and Digestion

Carbohydrates

Carbon, hydrogen and oxygen (simple + complex sugars)

Fats

Carbon, hydrogen and oxygen (lipids and fatty acids)

Protein

carbon, hydrogen, oxygen and nitrogen (amino acids)

Iodine

Starch

Benedict's solution

Sugars

Biuret

Proteins

Ethanol Emulsion

Fats and oils

Enzymes

Proteins that function as a biological catalyst

Enzyme-Substrate Complex

A temporary association formed when an enzyme binds to its active site, a chemical reaction occurs and a product forms

Increase in temperature causes?

Morse frequent collisions between enzymes and substrates.

What can denature and enzyme?

Temperatures past the optimum or the wrong pH level.

What colour does iodine solution turn when starch is present?

Blue/black

What colour does Biuret solution turn when protein is present?

Violet/purple

What colour does Benedict’s solution turn when sugar is present?

Green, yellow, orange or red

What colour does ethanol emulsion turn when fat is present?

Milky/cloudy white