Scientific Principles in Biology: Revision Sheet

1. 📌 Essentials

• The scientific method involves observation, hypothesis, experimentation, analysis, and conclusion.
• SI units: meter (m), kilogram (kg), second (s), mole (mol).
• Atomic structure: protons and neutrons nucleus; electrons orbit.
• Atomic number = number of protons; defines element.
• Isotopes differ in neutron count; used in medical imaging.
• Ionic: transfer electrons; form between metals and nonmetals.
• Covalent bonds: share electrons; can be polar or nonpolar.
• Hydrogen bonds: weak attractions stabilizing DNA and proteins.
• Water's high specific heat (4.18 J/g°C) buffers temperature.
• pH scale: 0-14, acids <7, neutral =7, bases >7.
• Buffers: maintain pH stability (e.g., bicarbonate buffer).
• Organic molecules: carbs, lipids, proteins, nucleic acids.
• Force = mass × acceleration; work = force × distance.
• Energy forms: kinetic, potential, chemical.
• Thermodynamics: energy conservation and entropy increase.

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