Biology, Chemistry, and Physics Notes PDF

Unit 1: Biology – Understanding Life Systems 1.1. Cells and Their Functions ​ Cell Theory: ○​ All living organisms are made of cells. ○​ The cell is the basic unit of life. ○​ All cells come from pre-existing cells. ​ Types of Cells: ○​ Prokaryotic cells:...

Unit 1: Biology – Understanding Life Systems 1.1. Cells and Their Functions ​ Cell Theory: ○​ All living organisms are made of cells. ○​ The cell is the basic unit of life. ○​ All cells come from pre-existing cells. ​ Types of Cells: ○​ Prokaryotic cells: No nucleus (e.g., bacteria). ○​ Eukaryotic cells: Have a nucleus (e.g., plant, animal, and fungi cells). ​ Cell Structures: ○​ Nucleus: Controls cell functions and contains DNA. ○​ Cytoplasm: Jelly-like substance where chemical reactions occur. ○​ Mitochondria: Powerhouse of the cell (energy production). ○​ Ribosomes: Make proteins. ○​ Cell Membrane: Controls what enters and exits the cell. ○​ Chloroplasts (in plant cells): Site of photosynthesis. ​ Cell Division: ○​ Mitosis: Division of body cells resulting in two identical cells. ○​ Meiosis: Division of sex cells resulting in four non-identical cells. 1.2. Tissues, Organs, and Systems ​ Levels of Organization: ○​ Cells → Tissues → Organs → Organ Systems → Organism. ​ Human Body Systems: ○​ Circulatory system: Transports nutrients, gases, and wastes. ○​ Digestive system: Breaks down food and absorbs nutrients. ○​ Respiratory system: Brings in oxygen and expels carbon dioxide. ○​ Nervous system: Controls and coordinates body activities. ○​ Excretory system: Removes waste products from the body. 1.3. Reproduction ​ Asexual Reproduction: One parent cell produces offspring (e.g., binary fission in bacteria). ​ Sexual Reproduction: Involves two parents; offspring are genetically different. Unit 2: Chemistry – Matter and Chemical Reactions 2.1. Properties of Matter ​ Physical Properties: Characteristics that can be observed without changing the substance (e.g., color, boiling point, density). ​ Chemical Properties: Describes how a substance reacts with other substances (e.g., flammability, reactivity with acids). ​ States of Matter: Solid, liquid, gas. Changes in temperature and pressure affect the state. 2.2. Atomic Theory ​ Structure of an Atom: ○​ Protons (positive charge) and neutrons (neutral) in the nucleus. ○​ Electrons (negative charge) orbit around the nucleus in electron shells. ​ Periodic Table: ○​ Organizes elements by atomic number. ○​ Metals, Non-metals, and Metalloids. ○​ Groups/Families: Vertical columns; elements in the same group have similar properties. ○​ Periods: Horizontal rows; properties change across a period. 2.3. Chemical Bonding ​ Ionic Bonding: Occurs between metals and non-metals; transfer of electrons (e.g., sodium chloride). ​ Covalent Bonding: Occurs between non-metals; sharing of electrons (e.g., water, H₂O). 2.4. Chemical Reactions ​ Types of Reactions: ○​ Synthesis: Two or more substances combine to form a compound. ○​ Decomposition: A compound breaks down into simpler substances. ○​ Combustion: A substance reacts with oxygen, releasing energy (e.g., burning fuels). ○​ Single Displacement: One element replaces another in a compound. ○​ Double Displacement: Two compounds exchange ions. ​ Balancing Chemical Equations: ○​ Law of Conservation of Mass: Matter is neither created nor destroyed in a chemical reaction. ○​ Ensure the number of atoms of each element is the same on both sides of the equation. Unit 3: Physics – Understanding Matter and Energy 3.1. Motion ​ Types of Motion: ○​ Linear motion: Movement in a straight line. ○​ Rotational motion: Movement around a central point or axis. ​ Speed and Velocity: ○​ Speed: Distance traveled per unit of time (Speed = Distance/Time). ○​ Velocity: Speed in a given direction (Velocity = Displacement/Time). ​ Acceleration: The rate at which velocity changes (Acceleration = Change in Velocity/Time). 3.2. Forces and Energy ​ Newton’s Laws of Motion: ○​ 1st Law (Inertia): An object at rest stays at rest; an object in motion stays in motion unless acted upon by an external force. ○​ 2nd Law (Force and Acceleration): Force equals mass times acceleration (F = ma). ○​ 3rd Law (Action and Reaction): For every action, there is an equal and opposite reaction. ​ Work and Energy: ○​ Work: Work is done when a force is applied to an object and it moves (Work = Force × Distance). ○​ Kinetic Energy: Energy of motion (KE = ½ mv²). ○​ Potential Energy: Stored energy due to an object's position (PE = mgh). ​ Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another. 3.3. Waves and Light ​ Types of Waves: ○​ Transverse Waves: Particles move perpendicular to the wave’s direction (e.g., light waves, water waves). ○​ Longitudinal Waves: Particles move parallel to the wave’s direction (e.g., sound waves). ​ Properties of Waves: ○​ Wavelength: Distance between two successive crests or troughs. ○​ Frequency: Number of waves that pass a point in one second. ○​ Amplitude: Maximum displacement of a wave from its equilibrium position. ​ Light and Optics: ○​ Reflection: Bouncing of light off a surface. ○​ Refraction: Bending of light as it passes from one medium to another (e.g., air to water). ○​ Lenses: Convex lenses converge light; concave lenses diverge light.