CB1 Key concepts in biology mind map

Microscopy

• Magnification: Image ÷ actual; eyepiece × objective
• Units: 1 mm = 1,000 µm; 1 µm = 1,000 nm
• Resolution: Separate close points; bigger ≠ clearer
• Preparation: Thin specimen, stain, coverslip; low power first
• Drawing: Clear lines, labels and scale

Cells

• Nucleus: DNA; control; animal / plant cells are eukaryotic
• Cytoplasm: Reactions; ribosomes make proteins
• Membrane: Controls movement in and out
• Mitochondria: Most aerobic respiration reactions
• Chloroplasts: Chlorophyll → light absorption
• Support: Vacuole: sap / pressure; wall: cellulose

Specialisation

• Adaptation: Structure suits function; sperm tail enables movement
• Egg: Nutrients; outer layer changes after fertilisation
• Microvilli: Large surface area → absorption
• Cilia: Move mucus towards throat
• Bacteria: Prokaryotic: no nucleus or mitochondria
• Features: DNA loop; plasmids / flagella / capsules vary

Enzymes

• Catalysts: Proteins; specific active site; reused
• Breakdown: Protease: protein → amino acids; amylase: starch → maltose
• Lipase: Fatty acids + glycerol; synthesis joins molecules
• Conditions: Optima; excess heat / extreme pH can denature
• Saturation: All active sites occupied → rate plateaus
• Investigation: Amount ÷ time; amylase / iodine; control / repeat

Transport

• Diffusion: Net particles: high → low concentration
• Speed: Gradient, heat, area ↑; distance ↓
• Osmosis: Water: dilute → concentrated; partially permeable membrane
• Plants: Water in: turgid; water out: flaccid → plasmolysed
• Animals: No wall: may burst or shrink
• Active: Low → high; carrier proteins; respiration supplies energy

Osmosis practical

• Method: Equal cylinders; sucrose range; blot and reweigh
• Change: (Final − initial) ÷ initial × 100%
• Direction: Mass gain: water in; mass loss: water out
• Graph: Repeat → mean; 0% crossing: no net water movement

Connections

• Cells → Transport: Membrane controls exchange
• Transport → Osmosis practical: Water movement changes potato mass