Enzymes and Digestion Demonstrations

Enzymes are biological catalysts that speed up chemical reactions in living things, including the breakdown of food during digestion. This category introduces the role of enzymes, their specificity, and the conditions that affect them. Understanding enzymes and digestion explains how organisms obtain and use the nutrients needed for life.

Demonstration	Materials	Difficulty	Safety	Summary
Length of the Digestive System	★☆☆	★☆☆	★☆☆	Students measure and lay out rope to represent the lengths of different digestive organs, showing the impressive distance food travels from mouth to anus. Along the way, they discuss each organ’s function and how the digestive system fits inside the body.
Making Poo: Modeling the Digestive System	★☆☆	★☆☆	★☆☆	Students create a hands-on model of the digestive system using everyday materials to show how food is broken down, nutrients are absorbed, and waste is excreted as poo. This activity helps students visualize and understand the stages of digestion and the role of each organ.
Pineapple Enzymes and Geletin	★☆☆	★☆☆	★☆☆	Bromelain in fresh pineapple prevents jelly from setting by digesting the gelatine protein.
Sweet Cracker	★☆☆	★☆☆	★☆☆	The enzyme amylase in saliva breaks down starch into sugar. A cracker initially tastes bland, but the longer it is chewed, the sweeter it becomes as starch is converted to glucose.
Yeast and Bread Fermentation	★☆☆	★☆☆	★☆☆	Students explore the role of yeast in bread making by preparing dough in a bag, observing changes over time, and investigating how yeast fermentation produces carbon dioxide that causes dough to rise.
Yeast Fermentation	★☆☆	★☆☆	★☆☆	Students investigate how different sugars (white sugar, brown sugar, and honey) affect the rate of yeast fermentation by measuring the amount of carbon dioxide produced, observed through balloon inflation.
Action of Salivary Amylase on Starch	★★☆	★★☆	★★☆	This demonstration shows how salivary amylase breaks down starch in cooked rice into simpler sugars like maltose. Students use chemical tests to identify starch and reducing sugars while learning about enzyme activity and its dependence on conditions such as temperature.
Cooking an Egg Without Heat	★★☆	★☆☆	★★☆	This experiment shows how alcohol can denature proteins in egg whites, causing them to coagulate and turn white, just like when cooking with heat. It demonstrates protein structure disruption and how proteins lose their natural shape under different conditions.
Pepsin Digestion of Protein	★★☆	★★☆	★★☆	Students investigate the effect of pepsin on albumin, a protein, under different conditions. By comparing test tubes with acid, boiled enzyme, and water, they observe how pepsin activity depends on temperature and pH, simulating the digestive process in the stomach.
Potato Catalase Hydrogen Peroxide Decomposition	★★☆	★☆☆	★☆☆	Students observe how the enzyme catalase in potato accelerates the decomposition of hydrogen peroxide into water and oxygen. By comparing room-temperature, boiled, and frozen potato, they explore how temperature affects enzyme activity.
Lactase Breakdown of Lactose	★★★	★★☆	★☆☆	Students use over-the-counter lactase and a lactose solution to show that lactase hydrolyzes lactose into glucose and galactose. Glucose test strips provide an easy color readout to confirm glucose formation.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff