O Levels/IGCSE Biology Lesson Plan 4.1

Section	Details
Objective	– List the chemical elements that make up carbohydrates, fats, and proteins. – Understand that large molecules are made from smaller molecules.
Activities	Starter (5 mins): Ask students what they think carbohydrates, fats, and proteins are made of and list their ideas. Main (25 mins): 1. Discuss the chemical composition of biological molecules: – Carbohydrates: Carbon, hydrogen, oxygen. – Fats: Carbon, hydrogen, oxygen. – Proteins: Carbon, hydrogen, oxygen, nitrogen (and sometimes sulfur). 2. Explain that large molecules are made from smaller molecules: – Starch, glycogen, cellulose from glucose. – Proteins from amino acids. – Fats and oils from fatty acids and glycerol. 3. Use diagrams to illustrate the formation of these large molecules. Plenary (10 mins): Students create a table listing the chemical elements and building blocks of carbohydrates, fats, and proteins.
Resources	Diagrams of carbohydrates, fats, and proteins, worksheets for summarizing elements and building blocks.
Time	40 minutes
Homework	Write a short explanation of how glucose forms starch, glycogen, or cellulose.
Assessment	Students correctly identify the chemical elements and building blocks of biological molecules during discussions and table creation.
Past Paper Practice	IGCSE Biology 0610/21/M/J/20 Q2(a).

Section	Details
Objective	– Describe and perform food tests for starch, reducing sugars, proteins, fats and oils, and vitamin C.
Activities	Starter (5 mins): Show a variety of food items and ask students to guess which contain starch, sugar, protein, or fat. Main (25 mins): 1. Demonstrate and explain each food test: – Iodine Test (Starch): Add iodine to food; blue-black color indicates starch. – Benedict’s Test (Reducing Sugars): Heat food with Benedict’s solution; orange-red precipitate indicates reducing sugars. – Biuret Test (Proteins): Add biuret solution; purple color indicates proteins. – Ethanol Emulsion Test (Fats and Oils): Mix food with ethanol, then water; white emulsion indicates fats/oils. – DCPIP Test (Vitamin C): Add DCPIP solution; decolorization indicates vitamin C. 2. Students perform food tests in groups and record their observations. Plenary (10 mins): Discuss which food items tested positive for each molecule and their significance in the diet.
Resources	Food samples, iodine solution, Benedict’s solution, biuret solution, ethanol, DCPIP solution, test tubes, droppers, heat source.
Time	40 minutes
Homework	Write a lab report summarizing the food tests and their results.
Assessment	Students correctly perform food tests and interpret their results during the practical session.
Past Paper Practice	IGCSE Biology 0610/22/O/N/19 Q3(b).

Section	Details
Objective	– Describe the structure of a DNA molecule, including the double helix, bases, and base pairing rules.
Activities	Starter (5 mins): Show an animation of a DNA molecule and ask students to describe its shape. Main (25 mins): 1. Explain the structure of DNA: – Two strands coiled into a double helix. – Each strand contains bases (A, T, C, G). – Base pairing rules: A pairs with T, C pairs with G. – Bonds between bases hold the strands together. 2. Use a model or diagram to illustrate the DNA structure and base pairing. 3. Discuss the role of DNA in carrying genetic information. Plenary (10 mins): Students construct a simple paper model of a DNA molecule, labeling the strands, bases, and pairings.
Resources	DNA models, diagrams of DNA, paper for model building.
Time	40 minutes
Homework	Draw and label a diagram of a DNA molecule, showing the double helix and base pairing.
Assessment	Students correctly describe and model the structure of DNA during class activities.
Past Paper Practice	IGCSE Biology 0610/41/M/J/19 Q4(c).

Use visual aids and models to explain complex structures like DNA.
Conduct food tests as a hands-on activity to reinforce theoretical knowledge.
Relate the significance of biological molecules to real-life examples, such as nutrition and genetic inheritance.