Cell Structure and Transport (Biology - B1)

Cell Structure and Transport (Biology - B1)

• Eukaryotic Cells: Found in plants and animals. Contain a nucleus, mitochondria, ribosomes, and chloroplasts (plants only). Also have a cell wall (plants only) for structure.
• Prokaryotic Cells: Found in bacteria. Lack a nucleus, small, and simple.
• Diffusion: Passive movement of particles from high to low concentration (e.g., oxygen in, carbon dioxide out).
• Osmosis: Diffusion of water through a semi-permeable membrane. Occurs in plant roots, for example.
• Active Transport: Movement of substances against their concentration gradient, requiring energy (ATP). Example: nutrient absorption in intestines.
• Magnification Formula: Magnification = Image size / Actual size. Important for microscopy.
• Microscopes: Light microscopes have low resolution compared to electron microscopes, which have high resolution.

Atomic Structure (Chemistry - C1)

• Subatomic Particles:
  • Protons: Positive (+1), mass of 1.
  • Neutrons: Neutral (0), mass of 1.
  • Electrons: Negative (-1), negligible mass.
• Atomic Number: Number of protons.
• Mass Number: Number of protons + neutrons.
• Electron Configuration: Electrons occupy energy levels or shells. The first shell holds a maximum of 2 electrons; second and third shells hold a maximum of 8 electrons each.
• Atomic Models:
  • Dalton: Solid sphere model.
  • Thomson: Plum pudding model (electrons in a positive "soup").
  • Rutherford: Nuclear model (positive nucleus, electrons outside).
  • Bohr: Electrons in fixed orbits (shells).

The Periodic Table (Chemistry - C2)

• Groups (Columns):
  • Group 1: Alkali metals (very reactive, 1 outer electron).
  • Group 7: Halogens (reactive non-metals, 7 outer electrons).
  • Group 0: Noble gases (inert, full outer shell).
• Periods (Rows): Show increasing atomic number.
• Trends:
  • Reactivity increases down Group 1 (easier to lose an electron).
  • Reactivity decreases down Group 7 (harder to gain an electron).

Energy (Physics - P1)

• Energy Stores: Thermal, kinetic, gravitational potential, elastic potential, chemical, nuclear, magnetic, electrostatic.
• Energy Transfers:
  • Mechanically: Force doing work.
  • Electrically: Work done by moving charges.
  • By heating: Temperature difference.
  • By radiation: Light or sound waves.
• Efficiency Formula: Efficiency = (Useful energy output / Total energy input) × 100.
• Renewable vs Non-renewable Resources:
  • Renewable: Solar, wind, hydro, geothermal, tidal.
  • Non-renewable: Coal, oil, natural gas, nuclear.