P1 BIOLOGY

• Larger concentration gradient


  Higher rate of diffusion
• Solutes are the dissolving molecules in water
• Solutes


  • Sugars
  • Salts
• Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration
• Specialized cells

  Different types of cells that make up complex organisms like animals and plants
• Examples of specialized cells in animals

  • Sperm cells
  • Muscle cells
  • Nerve cells
• Examples of specialized cells in plants

  • Root hair cells
  • Phloem cells
  • Xylem cells
• Sperm cell


  • Has half the genetic material of a normal adult cell
  • Has a flagellum to swim
  • Is streamlined to swim
  • Has many mitochondria for energy
  • Has digestive enzymes to break into egg
• Specialized cells


  Have a specific role, shape, structure and organelle composition to fulfill that role
• Differentiation


  The process by which cells become specialized
• Differentiation


  1. Single cell (zygote) divides

  2. Cells remain identical at first

  3. Cells then undergo changes to become specialized
• Stem cells


  Cells that can repeatedly divide by mitosis and differentiate into different types of specialized cells
• Stem cells


  Cells that can divide by mitosis to form more cells and can differentiate into specialized cells
• Stem cells


  • Can divide by mitosis to form more cells
  • Can differentiate into specialized cells
• Human life starts


  1. Sperm cell fertilizes egg cell

  2. Forms zygote

  3. Zygote divides by mitosis repeatedly

  4. Forms embryo

  5. Embryonic stem cells can differentiate into any cell type

  6. Cells continue to divide and differentiate

  7. Leads to baby after 9 months
• Embryonic stem cells


  Stem cells found in embryo that can differentiate into any cell type
• Adult stem cells


  Stem cells found in adult that can only differentiate into a narrow range of cell types
• Adult stem cells


  • Can divide by mitosis
  • Can only differentiate into a narrow range of cell types
  • Can replace damaged cells
• Plant stem cells


  Stem cells found in plant meristem tissues that can differentiate into plant cells and tissues
• Plant growth


  1. Unspecialized plant stem cells in meristem

  2. Differentiate into cells and tissues needed by plant

  3. Plant stem cells persist for plant's entire life
• Plant stem cells unlike embryonic stem cells persist for the plant's entire life
• Binary vision


  The process by which prokaryotic organisms like bacteria divide and reproduce
• Binary fission


  1. How binary vision works

  2. Bacterial cell grows in size

  3. Replicates genetic material (large circular DNA strand and plasmids)

  4. Two circular DNA strands move to opposite sides of cell

  5. Plasmids arrange randomly

  6. New cell wall grows down middle of cell

  7. Two new bacterial cells form
• Binary fission is not the same as mitosis or meiosis, which happen in eukaryotic cells
• Bacterial cell


  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Large circular DNA strand
  • Plasmids (smaller circular DNA)
• Some bacteria


  • Have a flagellum (tail to move around)
• Binary fission


  A type of asexual reproduction for single-celled organisms
• Bacteria can divide once every 20 minutes under optimal conditions
• Bacterial population growth


  Doubles with each division cycle
• Calculating bacterial population growth

  1. Divide total time by mean division time to get number of division cycles

  2. Multiply initial population by 2 raised to the power of number of division cycles
• Mean division time depends on bacterial species and environmental conditions
• Optimal growth conditions for bacteria

  • Warm
  • Moist
  • Plenty of nutrients
• Lack of optimal conditions slows or stops bacterial division
• Biological molecules/nutrients


  Carbohydrates, lipids, proteins, vitamins, mineral ions, fiber, water
• Foods normally have a mix of different nutrients, not just one
• Carbohydrates


  Found in starchy foods, fruits, vegetables; provide energy
• Lipids


  Fats and oils; provide energy, insulate, protect organs
• Proteins


  Found in nuts, seeds, meat, fish, legumes; building blocks for growth and repair
• Vitamins


  Organic molecules made by living organisms; needed in small amounts
• Vitamin A


  • Found in liver, leafy vegetables; for vision, skin, hair