Biology

Subdecks (14)

Cards (524)

  • Leaf adaptation for efficient gas exchange
    1. Broad and Thin
    2. Large surface area to volume ratio; no cell far from air
    3. 2. Large number of air spaces within leaf
  • Upper epidermis
    Transparent
    • Allows light to pass through
  • Palisade Mesophyll
    Lots of chloroplasts
    • For photosynthesis
    Stacked
    • More light can be captured
  • Spongy Mesophyll
    Air spaces
    • Allows diffusion to occur more efficently.
  • Xylem
    Carries water and minerals
  • Phloem
    Carries sucrose
  • Mass transport
    Bulk movement of gases or liquids in one direction
  • Haemoglobins
    A group of chemically similar molecules found in many different organisms
  • Haemoglobin consists of four polypeptide chains
    • 2 alpha 2 beta
  • Each polypeptide chain is associated with a prosthetic haem group
  • Haem group contains an Fe2+ ion
  • Each haemoglobin molecule can carry four oxygen molecules.
  • Haemoglobin combines with oxygen to form oxyhaemoglobin.
  • Association of oxygen
    Process which haemoglobin binds with oxygen.
    • Occurs in lungs
  • Dissociation of oxygen
    Process which oxygen is released from haemoglobin
    • Occurs in lungs for haemoglobin to bind to oxygen again.
  • Affinity
    Degree to which one substance combines with another.
    • Haemoglobin affinity changes under different conditions by changing its shape in the presence of certain substances.
  • Different species have different types of haemoglobin. 

    Different oxygen transport properties adapted to the environment of each animal
  • Haemoglobin is a globular protein
  • Four globin subunits are held together by disulphide bonds
    Hydrophobic R groups face inwards
    • Preserve the 3D spherical shape
    Hydrophilic R groups face outwards
    • Maintain solubility
  • Reasons why molecules cannot pass through cell-surface membrane through simple diffusion.
    1. Too large
    2. Polar
    3. Hydrophilic
  • Production of calibration curves
    1. Make solutions of known concentrations and carry out quantitative tests on each.
    2. Use colorimeter to measure colour value of each solution and plot calibration curve.
    3. Concentration on x-axis, Colorimeter reading on y-axis
    4. Find concentration of sample from calibration curve interpolation.
  • Exopeptidase
    Hydrolyses peptide bonds at ends.
    • Removes amino acids at ends
  • Endopeptidase
    Hydrolyse internal peptide bonds.
    • Break proteins into shorter chains
    • Increases surface area; number of ends
  • Why use a colourimeter
    Improves repeatability of results
    • Quantitative; subjective colour change
    • Standardises method
  • Countercurrent Flow
    Blood and water flow in opposite directions
    • Maintains constant concentration gradient
    • Diffusion occurs throughout the lamellae
  • Endopeptidases
    Hydrolyse bonds at ends of polypeptides into dipeptides.
  • Endoeptidases
    Hydrolyses middle of polypeptide chains into shorter polypeptides
  • Digestion
    Hydrolysis of large insoluble molecules into smaller soluble molecules
  • Hydrogen bonds
    Form between strongly polar R groups
    • Weakest bonds
    • Most common
  • Hydrophobic interactions
    Form between the non-polar (hydrophobic) R groups within the interior of proteins.
  • Cell division occurs at the apex