OCR A Level Biology A Module 2: Foundations in Biology Exam Questions

About OCR A Level Biology A Module 2: Foundations in Biology

Module 2 of OCR A Level Biology A, Foundations in Biology, provides the molecular and cellular basis for everything else in the course. It covers microscopy and cell ultrastructure, carbohydrates, lipids and proteins, nucleotides, DNA replication and protein synthesis, enzymes, membrane structure and transport, and the cell cycle with mitosis and meiosis. Because it underpins every other module, it can appear on all three A Level papers as well as both AS papers. Examiners frequently ask for magnification calculations, biochemical tests, structure-to-function explanations, enzyme rate graphs, water potential and the stages of mitosis.

What you need to know

• 2.1.1 Light, transmission electron and scanning electron microscopes, magnification and resolution, using an eyepiece graticule and stage micrometer, and the ultrastructure of eukaryotic and prokaryotic cells including the cytoskeleton.
• 2.1.2 Properties of water, structure of glucose, starch, glycogen and cellulose, triglycerides and phospholipids, protein structure from primary to quaternary, fibrous and globular proteins, and tests for reducing and non-reducing sugars, starch, lipids and proteins, including colorimetry and chromatography.
• 2.1.3 Nucleotide structure including ADP and ATP, DNA structure, semi-conservative replication, the genetic code, and transcription and translation.
• 2.1.4 Enzyme action including lock and key and induced fit, factors affecting rate, temperature coefficient Q10, cofactors, coenzymes and prosthetic groups, and competitive, non-competitive and end-product inhibition.
• 2.1.5 The fluid mosaic model, the effects of temperature and solvents on membrane permeability, diffusion, facilitated diffusion, active transport, bulk transport and osmosis in terms of water potential.
• 2.1.6 The cell cycle and its checkpoints, mitosis and meiosis, specialised cells (for example erythrocytes, neutrophils, squamous and ciliated epithelia, palisade cells, guard cells, root hair cells), and stem cells.

Common mistakes in Module 2: Foundations in Biology

• Confusing magnification with resolution. Magnification is how many times larger the image is; resolution is the ability to distinguish two close points as separate.
• Saying the Benedict's test detects all sugars directly. Non-reducing sugars such as sucrose must first be hydrolysed by boiling with dilute acid and neutralised before Benedict's gives a positive result.
• Describing DNA replication as conservative. Each new molecule contains one original strand and one new strand.
• Writing that cells burst in a hypotonic solution regardless of type. Animal cells may lyse, but plant cells become turgid because the cell wall resists expansion.
• Stating that cytokinesis is a stage of mitosis. Mitosis is nuclear division; cytokinesis is the division of the cytoplasm that follows.

Try three Module 2: Foundations in Biology exam-style questions