Mod 2

• Colonial organisms are a collection of unicellular organisms, all living together and performing the same functions
• Advantages of living in a colony

  • Stronger defence
  • Ability to attack bigger prey
  • Less energy expenditure
• Cell differentiation is the process by which cells become specialized to perform different functions
• Multicellular organisms have a hierarchical structure of tissues, organs, and organ systems to meet their needs
• Cells may be flattened or elongated to increase surface area to volume ratio
• Cells may have exposed edges extended into folds to increase surface area for absorption
• Cell differentiation increases effectiveness in carrying out functions due to division of labour
• Undifferentiated cells that can divide and differentiate into other types of cells are known as stem cells
• Stem cells are undifferentiated cells
• Specialized cells are formed when differentiation of the stem cells occurs
• Adult stem cells continue to differentiate and replenish stocks of blood cells
• Photoautotrophs


  Autotrophs that carry out photosynthesis using sunlight
• Chemoautotrophs


  Autotrophs that obtain energy from inorganic chemical reactions
• Vascular plants

  • Have true roots, stems, and leaf systems
  • Possess transport systems (xylem and phloem)
• Non-vascular plants

  • Lack true roots, stems, and leaf systems
  • Rely on osmosis and diffusion
• Vascular tissues (xylem and phloem) move substances in vascular plants
• Macroscopic structures

  Structures that can be seen with the naked eye
• Microscopic structures


  Structures that can only be seen using a microscope
• Male components of a flower

  • Stamen (anther and filament)
• Female components of a flower

  • Pistil (stigma, style, ovary)
• Pollination

  Pollen from the anther is transferred to the stigma
• Fertilization


  Pollen travels down the style and reaches the ovules inside the ovary
• Common structures seen under light microscope

  • Stoma
  • Guard cell
  • Mesophyll
  • Vascular bundle
• Leaf structure/adaptation

  • Thin and flat for maximum absorption of light
  • Epidermis allows light penetration
  • Waxy cuticle prevents water loss
• Plants in extreme sun exposed areas will have smaller leaves to reduce water loss
• Leaves may be silver to reflect light
• Palisade Cells


  Contains many chloroplasts, main site for photosynthesis
• Spongy mesophyll


  Cells are loosely and irregularly organised to allow easy movement of gases
• Leaf adaptations for gas exchange

  • Large and usually flat
  • Open air spaces (spongy mesophyll)
  • Moist cell surfaces
• Most gaseous exchange occurs through stomata and lenticels
• Lenticels


  Pores through which gas exchange occurs in the woody parts of the plant
• The diffusion of oxygen, carbon dioxide, and water vapour through lenticels is relatively slow
• Components of the stem

  • Dermal tissue
  • Vascular tissue
  • Ground tissue
• Dermal tissue


  Outer layer of the stem providing waterproofing and protection
• Vascular tissue


  Consists of xylem (transports water and minerals) and phloem (transports glucose)
• Ground tissue


  Fills around the vascular tissue
• Root hairs near the tip of the roots increase surface area for absorption
• Chloroplasts contain the green pigment called chlorophyll, which traps sunlight
• Reactants for photosynthesis

  • Water
  • Carbon dioxide

  
• Light phase

  1. Happens in the thylakoid

  2. Needs sun’s energy

  3. Water is broken down to release hydrogen and oxygen