Basic Physics, Chemistry, and Biology – General Knowledge Notes

 Basic Physics

Physics is the study of matter, energy, and the fundamental forces of nature. Here are key concepts in basic physics:

• Newton’s Laws of Motion:
  1. First Law (Inertia): An object will remain at rest or in uniform motion unless acted upon by an external force.
  2. Second Law (Force and Acceleration): Force = mass × acceleration (F = ma).
  3. Third Law (Action and Reaction): For every action, there is an equal and opposite reaction.
• Speed, Velocity, and Acceleration:
  • Speed: Distance traveled per unit time (e.g., meters per second).
  • Velocity: Speed in a specific direction.
  • Acceleration: Rate of change of velocity over time.
• Gravitation:
  • All masses attract each other with a force called gravity.
  • Law of Universal Gravitation: The gravitational force between two objects is proportional to their masses and inversely proportional to the square of the distance between them.
• Energy:
  • Kinetic Energy: Energy of motion (KE = ½ mv²).
  • Potential Energy: Energy stored due to position (e.g., gravitational potential energy = mgh).
  • Law of Conservation of Energy: Energy cannot be created or destroyed, only converted from one form to another.
• Waves and Light:
  • Wave: A disturbance that transfers energy from one place to another.
  • Electromagnetic Spectrum: Includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
  • Reflection and Refraction: Light can reflect off surfaces and bend when passing from one medium to another.

 Basic Chemistry

Chemistry is the study of matter and the changes it undergoes. Key concepts in basic chemistry:

• Elements, Compounds, and Mixtures:
  • Element: A pure substance consisting of only one type of atom (e.g., Hydrogen, Oxygen).
  • Compound: A substance made of two or more different atoms chemically bonded together (e.g., H₂O, CO₂).
  • Mixture: A combination of two or more substances that are not chemically bonded (e.g., air, saltwater).
• Atomic Structure:
  • Atom: The basic unit of matter, composed of protons, neutrons, and electrons.
  • Protons: Positively charged particles in the nucleus.
  • Neutrons: Neutral particles in the nucleus.
  • Electrons: Negatively charged particles orbiting the nucleus.
• Periodic Table:
  • Arranged by increasing atomic number.
  • Groups represent elements with similar chemical properties.
• Chemical Reactions:
  • Reactants: Substances that undergo a chemical change.
  • Products: Substances formed from the reaction.
  • Law of Conservation of Mass: Mass is conserved in a chemical reaction; the total mass of reactants equals the total mass of products.
• Acids, Bases, and pH:
  • Acids: Substances that donate hydrogen ions (H⁺) in solution (e.g., HCl).
  • Bases: Substances that accept hydrogen ions or donate hydroxide ions (OH⁻) in solution (e.g., NaOH).
  • pH Scale: Measures the acidity or basicity of a solution. pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.

 Basic Biology

Biology is the study of living organisms and their interactions with the environment. Key concepts in basic biology:

• Cell Structure:
  • Cell: The basic unit of life.
  • Prokaryotic Cells: Simple cells without a nucleus (e.g., bacteria).
  • Eukaryotic Cells: Complex cells with a nucleus (e.g., plant and animal cells).
  • Cell Organelles: Key components like the nucleus, mitochondria, and ribosomes.
• DNA and Genetics:
  • DNA (Deoxyribonucleic Acid): The molecule that carries genetic information.
  • Genes: Units of heredity found in DNA that determine traits.
  • Chromosomes: Structures within cells that contain DNA.
  • Mendelian Inheritance: Patterns of inheritance discovered by Gregor Mendel, including dominant and recessive traits.
• Photosynthesis:
  • Process by which plants convert sunlight, water, and carbon dioxide into glucose (food) and oxygen.
  • Takes place in the chloroplasts of plant cells.
  • Equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
• Respiration:
  • Cellular Respiration: The process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.
  • Aerobic Respiration: Requires oxygen.
  • Anaerobic Respiration: Occurs without oxygen (e.g., in yeast, fermentation).
• Human Body Systems:
  • Circulatory System: Transports blood and nutrients (heart, blood vessels).
  • Respiratory System: Allows for gas exchange (lungs, trachea).
  • Digestive System: Breaks down food into nutrients (stomach, intestines).
  • Nervous System: Controls body functions (brain, spinal cord, nerves).
  • Endocrine System: Regulates hormones (glands like the thyroid, adrenal).