Biology Fundamentals

Distinguishing Living Things

  • Living things differ from non-living matter through several key characteristics:

    • Composed of cells.
    • Use energy.
    • Grow.
    • Reproduce.
    • Respond to their environment.
    • Maintain internal stability (homeostasis).
    • Evolve over generations.

  • Example: A plant can grow, heal, and reproduce, unlike a rock.

Homeostasis

  • Homeostasis is maintaining a stable internal environment.
    • Analogy: A house's thermostat keeps the temperature steady; living things regulate conditions like temperature or water levels.
    • Example: Sweating cools the body to maintain balance.

Biomolecules

  • Biomolecules are crucial for life processes:
    • Carbohydrates: Provide quick energy (fuel).
    • Proteins: Build structures and act as enzymes to speed up reactions (workers).
    • Lipids: Store long-term energy and form cell membranes.
    • Nucleic Acids (DNA and RNA): Carry hereditary information (biological blueprint).

Prokaryotic vs. Eukaryotic Cells

  • Prokaryotes:
    • Lack a nucleus.
    • DNA floats freely (e.g., bacteria).
  • Eukaryotes:
    • Have a nucleus to house DNA.
    • Contain specialized organelles (e.g., plants and animals).
    • Compartmentalization allows for more complex functions.

Organelles

  • Organelles have unique roles within the cell:
    • Analogy: Cell as a bustling city.
      • Nucleus: City hall, managing information.
      • Mitochondria: Power plants, producing energy.
      • Ribosomes: Factories, making proteins.
      • Chloroplasts: Solar panels (in plants), capturing sunlight for photosynthesis.
      • Cell Membrane: City walls, controlling what enters or exits.

Transport

  • Passive Transport:
    • Diffusion and osmosis allow molecules to move without energy.
    • Analogy: People drifting with a crowd.
  • Active Transport:
    • Requires energy to move substances against a gradient.
    • Analogy: Climbing uphill.

Cell Cycle

  • The cell cycle is a cell's life story from growth to division.

Mitosis

  • Mitosis is the stage where a single cell divides to form two identical daughter cells.
    • Crucial for growth, tissue repair, and replacing old cells.
    • Example: Healing a scraped knee involves mitosis to grow new skin cells.
  • Genetic Material:
    • Before mitosis, the cell replicates its DNA so that each daughter cell gets an exact copy.
    • Analogy: Copying a book before lending ensureseach friend gets the same information.
    • Errors can lead to diseases like cancer, where cell division goes unchecked.
  • Checkpoints:
    • Built-in checkpoints ensure everything proceeds correctly.
    • If errors are detected, the cycle can pause for repairs or trigger cell death.

DNA and Genetics

  • DNA stores and transmits genetic information:
    • Double helix structure with bases A, T, C, G encoding instructions for building proteins.
    • During replication, DNA makes an exact copy of itself.
  • Protein Synthesis:
    • Transcription: Copies a gene's information into messenger RNA (mRNA).
    • Translation: Occurs at the ribosome, where the mRNA's code is read and assembled into a protein.
  • Inheritance:
    • Genes have variants called alleles.
    • Dominant alleles: Only one copy needed to show the trait.
    • Recessive alleles: Require two copies to show the trait.
    • Punnett squares predict trait inheritance.

Photosynthesis and Cellular Respiration

  • Photosynthesis:
    • Plants capture sunlight, converting CO_2 and water into glucose and oxygen.
    • Nature's solar panel, storing energy for food webs.
  • Cellular Respiration:
    • Occurs in all cells, unlocking the stored energy in glucose, producing ATP to power cellular activities.

Cycles of Matter

  • Carbon Cycle: Moves CO_2 through air, plants, and animals, preventing resource depletion.
  • Nitrogen and Water Cycles: Ensure organisms have access to nutrients and hydration, maintaining ecological balance.

Energy Transfer

  • Energy flows through food chains and webs.
    • Producers (plants) capture solar energy.
    • Herbivores eat plants, carnivores eat herbivores, and so on.
    • Only about 10% of energy moves up each level; the rest is lost as heat.

Human Body

  • Organ Systems:
    • Respiratory System: Brings in oxygen.
    • Digestive System: Breaks down food into nutrients.
    • Circulatory System: Delivers oxygen and nutrients to cells.
  • Excretory and Nervous Systems:
    • Excretory System (Kidneys): Removes waste to keep the body's internal environment stable.
    • Nervous System: Uses electrical signals to monitor and respond to changes.
  • Homeostasis in Action:
    • When you exercise, muscles need more oxygen and produce more CO_2.
    • Breathing rate increases, the heart pumps faster, and kidneys filter extra waste.

Evolution

  • Natural Selection:
    • Individuals with advantageous traits survive and reproduce more successfully.
    • Over generations, these traits become more common.
    • Example: Peppered moths in industrial England shifted from light to dark coloration.
  • Evidence for Evolution:
    • Fossil records show gradual changes.
    • DNA analysis reveals genetic similarities.
    • Comparative anatomy highlights shared structures across species.
  • Adaptation:
    • Traits shaped by natural selection that enhance survival.
    • Examples: Webbed feet in aquatic birds or antibiotic resistance in bacteria.

Test Strategies

  • Read each question carefully.
  • Use the process of elimination.
  • Recall key terms like DNA, mitosis, or organelle functions.
  • Open Response Strategies:
    • Practice writing full, clear sentences that directly answer the question.
    • Support explanations with examples.
    • Don't leave blanks; partial credit is better than none.
    • Review sample questions and create flashcards for tricky topics.

Final Advice

  • Stay curious and connect concepts to real life.
  • When you see biology in the world (gardening, sports, cooking), it reinforces learning.