Biology Notes

Module 1: Cells as the Basis of Life

Cell Structure

• Cell: Smallest unit of a living organism; building blocks of life.
• Main Organelles:
  • Nucleus: Contains genetic material for growth, repair, and functioning.
  • Nucleolus: Produces ribosomes, made of proteins and RNA.
  • Ribosomes: Protein synthesis, found in cytoplasm or attached to ER.
  • Endoplasmic Reticulum (ER): Transport network; Rough ER (with ribosomes) makes lipids, Smooth ER processes proteins.
  • Golgi Body: Processes and packages cellular substances.
  • Lysosomes: Vesicles with digestive enzymes, breaking down waste.
  • Chloroplasts: Photosynthesis in plant cells, containing chlorophyll.
  • Mitochondria: Energy production (ATP) through respiration.
  • Cell Membrane: Semi-permeable barrier regulating substance movement.
  • Cell Wall: Structural support in plants, fungi, some prokaryotes.
  • Cytoplasm: Suspends organelles, gives cell shape.
  • Cytoskeleton: Organelles support.
  • Centrioles: Cell division role.
  • Pili/Flagella: Movement aid.
  • Vacuole: Storage; large in plants, small in animals.

Fluid-Mosaic Model

• Structure: Phospholipid bilayer with hydrophilic heads and hydrophobic tails.
• Transport:
  • Active Transport: Requires energy, against concentration gradient.
  • Passive Transport: No energy required, along concentration gradient.

Prokaryotes and Eukaryotes

Microscope

• Light Microscope: Uses light and lenses for magnification.
• Electron Microscope: Uses electron beams for higher magnification/resolution.

Transport of Materials

• Permeability:
  • Small, uncharged molecules pass easily.
  • Large, charged molecules do not.
• Solubility: Like dissolves like (hydrophilic vs. hydrophobic).
• Diffusion: Movement from high to low concentration.
• Osmosis: Water movement from high to low concentration.
• Active Transport: Against concentration gradient.

Cell Requirements

• Autotrophs: Make own food via photosynthesis.
• Heterotrophs: Consume other organisms for energy.
  • Organic Compounds: Carbohydrates, lipids, proteins, nucleic acids.
  • Inorganic Compounds: Water, oxygen, carbon dioxide, minerals.

Waste Removal

• Cellular Level: Diffusion, osmosis, and active transport.
• Body System Level: Organs like lungs, liver, kidneys.

Photosynthesis

• Stages:
  • Light-dependent: Sunlight splits water into oxygen and hydrogen.
  • Light-independent: CO2 and hydrogen form glucose.

Respiration

• ATP: Energy currency from breaking down glucose.
• Aerobic & Anaerobic Respiration: Oxygen presence determines method.

Enzymes

• Biological Catalysts: Speed up reactions.
• Models: Lock and key, induced fit.
• Factors Affecting Activity: Temperature, pH, substrate concentration.

Module 3: Biological Diversity

Environment Effects

• Selection Pressures: Influence survival and reproduction.
• Impact: Population size, evolutionary changes.

Adaptations

• Types:
  • Structural: Physical features.
  • Physiological: Internal functions.
  • Behavioral: Actions for survival.

Evolution

• Natural Selection: Favorable traits increase survival.
• Micro vs. Macroevolution: Small allele changes vs. new species formation.

Evidence of Evolution

• Fossils: Indicate transitions and biodiversity.
• DNA Sequencing: Genetic comparisons.
• Comparative Anatomy: Homologous and analogous structures.

Module 4: Ecosystems

Definitions

• Ecosystem: Interaction between biotic and abiotic factors.
• Population, Community, Habitat: Levels of organization.

Population Dynamics

• Carrying Capacity: Maximum population size sustainable.
• Competition: Interspecific and intraspecific.

Symbiotic Relationships

• Types:
  • Mutualism: Both benefit.
  • Commensalism: One benefits, one unaffected.
  • Parasitism: One benefits, one harmed.
  • Amensalism: One harmed, one unaffected.

Human Impact and Extinction

• Habitat Destruction: Fragmentation leads to extinction.
• Invasive Species: Outcompete native species.
• Overexploitation and Pollution: Reduce biodiversity.
• Climate Change: Affects ecosystems globally.