This page details the procedure for examining onion skin cells under a microscope, including proper slide preparation and microscope usage.

Definition: Light microscopy involves using visible light and lenses to magnify specimens for observation.

Example: The magnification calculation: Total magnification = Eyepiece lens × Objective lens

Key components covered include:

• Slide preparation steps
• Microscope parts identification
• Common errors in slide preparation
• Magnification calculations

Vocabulary: Stage clip - holds the slide in place during observation Vocabulary: Condenser - focuses light onto the specimen

Details the process of investigating bacterial growth and antiseptic effectiveness using agar gel and glass petri dishes.

Definition: An autoclave is a pressure chamber used to sterilize equipment and materials using high-pressure steam.

The procedure includes:

• Sterilization methods
• Plate preparation
• Antiseptic testing
• Results measurement and recording

Highlight: The zone of inhibition measurement requires taking two diameter measurements at 90° angles for accuracy.

Explains the investigation of osmosis using potato tissue, demonstrating how cells respond to different solution concentrations.

Definition: Osmosis is the movement of water molecules from an area of higher water concentration to an area of lower water concentration across a partially permeable membrane.

The practical includes:

• Potato cylinder preparation
• Mass measurement techniques
• Solution preparation
• Data recording and calculations

Example: Percentage change calculation: $Final Mass - Initial Mass$ × 100 ÷ Initial Mass

Details the investigation of how pH affects enzyme activity using amylase and starch.

Definition: Enzymes are biological catalysts that speed up chemical reactions in living organisms.

The procedure covers:

• Buffer solution preparation
• Timing techniques
• Iodine testing
• Result recording methods

Highlight: The speed of color change indicates enzyme activity rate.

Outlines various food tests for identifying different biological molecules.

The tests include:

• Benedict's test for reducing sugars
• Iodine test for starch
• Emulsion test for lipids
• Biuret test for proteins

Example: Benedict's solution turns from blue to brick red in the presence of reducing sugars.

Vocabulary: Water bath - equipment used to heat test tubes at a controlled temperature

Describes the method for measuring the rate of photosynthesis using pondweed.

Definition: Photosynthesis is the process by which plants convert light energy into chemical energy.

The practical involves:

• Setting up pondweed in water
• Measuring bubble production
• Varying light distance
• Recording results

Highlight: Bubble count over time indicates photosynthesis rate.

The first page outlines the six core required practicals biology paper 1 experiments that students need to master:

1. Microscopy: Examining cells and tissues
2. Microbiology: Studying microorganisms
3. Osmosis: Investigating cell transport
4. Photosynthesis: Understanding plant processes
5. Enzymes: Exploring biological catalysts
6. Food Tests: Identifying biological molecules

Highlight: These practicals form the foundation of practical assessment in AQA GCSE Biology.