Biology: Food Chains and Ecosystems

Biology

• Food Chains: Linear sequences showing energy transfer. Example: Grass → Grasshopper → Frog → Snake → Hawk
• Food Webs: Complex interconnected networks of food chains in an ecosystem.
• Trophic Levels:
  • Producers (Autotrophs): Convert solar energy to chemical energy (plants).
  • Primary Consumers: Herbivores (rabbits).
  • Secondary Consumers: Carnivores/omnivores eating herbivores (foxes).
  • Tertiary Consumers: Top predators (eagles).
• Producers: Organisms making their own food (plants, algae).
• Consumers:
  • Herbivores: Eat only plants (deer).
  • Carnivores: Eat only animals (lions).
  • Omnivores: Eat both plants and animals (humans).
• Sustainability: Maintaining ecological processes over time. Key concepts: biodiversity resilience, avoid resource over-exploitation, balance environment, economics, and social factors.
• Nitrogen Cycle: Nitrogen fixation, nitrification, denitrification, decomposition. Key terms: ammonia, nitrate, nitrogen gas.
• Water Cycle: Evaporation, condensation, precipitation, runoff, infiltration, transpiration.
• Carbon Cycle: Photosynthesis, respiration, combustion, decomposition move carbon through atmosphere, biosphere, oceans, and lithosphere.
• Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
• Cellular Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy. Photosynthesis stores energy, respiration releases it.
• Tolerance Range: Range of abiotic factors where an organism survives.
• Optimal Range: Conditions where organisms thrive.
• Limiting Factors: Abiotic/biotic factors restricting population growth (temperature, water).

Chemistry

• Matter and Mixtures:
  • Solution: Homogeneous mixture (saltwater).
  • Compound: Two+ elements chemically combined (H₂O).
  • Element: Pure substance of one atom type (oxygen).
  • Mechanical Mixture: Heterogeneous mixture (salad).
• Physical Properties: Characteristics observed without changing identity (density, color, boiling point).
• Chemical Properties: Describe reactivity (flammability, reactivity with acid).
• Physical Change: Changes state or appearance (melting ice).
• Chemical Change: Produces new substances (rusting).
• Density: Density = Mass ÷ Volume.
• Unusual Water Behavior: High specific heat capacity, expands when frozen (less dense as a solid).
• Metals, Non-Metals, Metalloids:
  • Metals: Shiny, conductive, malleable (iron).
  • Non-Metals: Dull, brittle, poor conductors (sulfur).
  • Metalloids: Properties of both (silicon).
• Periodic Table:
  • Families: Alkali metals, alkaline earth metals, halogens, noble gases.
  • Trends: Atomic size decreases across a period; reactivity varies (metals more reactive down a group).
  • Atomic Number: Number of protons.
  • Mass Number: Protons + Neutrons.
• Bohr-Rutherford Diagrams: Showing protons, neutrons, and electron arrangement around nucleus.
• Molecular vs. Ionic Compounds:
  • Molecular: Nonmetals sharing electrons (H₂O).
  • Ionic: Metals transferring electrons to nonmetals (NaCl).
• Hydrogen Peroxide: Decomposes into water and oxygen; store in cool, dark conditions.

Physics

• Law of Electric Charges: Like charges repel, opposite attract.
• Static vs. Current Electricity:
  • Static: Buildup of charges.
  • Current: Flow of electrons in a circuit.
• Charging Methods:
  • Friction: Rubbing transferring electrons.
  • Conduction: Direct contact transferring charge.
  • Induction: Nearby charged object inducing charge.
  • Grounding: Removing excess charge by connecting to Earth.
• Circuits: Components (resistor, switch, battery, bulb).
  • Series Circuits: One path, shared voltage.
  • Parallel Circuits: Multiple paths, equal voltage.
• Efficiency: (Useful energy output ÷ Total energy input) × 100%.
• Electrical Power: P = IV (Power = Current × Voltage).
• Cost of Energy: Energy (kWh) = Power (kW) × Time (h).

Space

• Celestial Objects:
  • Meteoroid: Small rock in space.
  • Meteor: Burns in Earth's atmosphere.
  • Meteorite: Reaches Earth's surface.
  • Asteroid: Rock orbiting the Sun.
  • Comet: Ice and dust, tail forms near the Sun.
• Planets:
  • Gas Giants: Jupiter, Saturn, Uranus, Neptune.
  • Terrestrial: Mercury, Venus, Earth, Mars.
• Earth's Motion:
  • Rotation: Earth spins (day/night).
  • Revolution: Earth orbits Sun (year).
• Satellites:
  • Natural: Moon.
  • Artificial: Communication, weather, GPS.
• Other Concepts:
  • Redshift: Light stretches as objects move away.
  • Polaris: North Star; aligns with Earth's axis.
  • Eclipses:
    • Solar Eclipse: Moon blocks Sun.
    • Lunar Eclipse: Earth blocks sunlight from Moon.