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water - Coggle Diagram

- - - - upward force exerted by water on object = object's weight
        
        Po > Pw, gravity > buoyancy, object sinks
        
        Po < Pw, gravity < buoyancy, object floats
    - - BLT
        
        solid bones to allow it to enter water (not hollow bones that most birds have for flight)
      - RS
        
        layer of blubber fat underneath skin to increase buoyancy
  - - - low η (eg impure water)
      - high η (eg pure water, bitumen)
    - - BLT
        
        ηwater > ηair, enabling BLT to fly through air without much friction
      - RS
        
        Since ηwater is high, RS have adaptations eg flippers, webbed feet, streamlines body.
  - - - water has relatively high thermal conductivity, making air a better insulator than water
        
        aquatic vs land-based warm-blooded animals
        
        aquatic
        
        greater risk of heat loss to surrounding water, esp in cold climates
        
        need adaptations (eg blubber, fur)
        
        land-based
        
        lower risk of heat loss to surrounding air (insulator)
        
        role of blood
        
        contains high water content (efficient heat transfer)
        
        carries heat from where it is generated (muscles, liver) to...
        
        parts that need more heat
        
        parts that can dissipate heat more easily to the environment (skin, lungs)
        
        adaptations
        
        BLT
        
        spends much of its time diving into water for food, thus it has an insulating layer of air trapped in its feathers
        
        RS
        
        has an insulating layer of blubber to maintain temp
      - fats and oils are poorer conductors of heat than water -> good insulators
  - - - water has high c (4.18J/g/K) as hydrogen bonds restrict molecular motion -> a lot of energy needs to be gained / lost for water's temp to increase / decrease -> thus water has relatively stable temp than air, making aquatic habitats more thermally stable than terrestrial habitats.
      - water can act as a coolant as it has high latent heat of vaporisation so during evaporation, a lot of energy is removed from the body
      - Adaptations
        
        RS
        
        RS is an arctic animal, able to survive through the year due to relatively stable temp, allowing for optimal enzyme function
- - - - mineral ions are transported in xylem sap
      - sucrose + other products of p/s are transported in phloem sap
    - - NaCl (ionic compound, polar, hydrophilic)
        
        dissolves in water to form Na+ and Cl- and carried in blood plasma
      - AA (hydrophilic AA and hydrophobic AA)
        
        solubility varies but ALL are soluble enough to be carried dissolved in blood plasma
      - C6H12O6 glucose (polar, hydrophilic)
        
        soluble in water and carried in blood plasma
      - O2 oxygen (non-polar, hydrophobic)
        
        binds with haemoglobin in RBC to form oxyhemoglobin
        
        why is it not transported by blood plasma?
        
        small size of oxygen allows it to dissolve sparingly in water, making water saturated with oxygen at low concentrations
        as temp increases, solubility of oxygen decreases
        thus blood plasma cannot transport sufficient oxygen around the body for aerobic cell respiration
      - fats and cholesterol (non-polar, hydrophobic)
        
        suspended in blood plasma while being transported
        
        to prevent coalescence, small fat molecules are coated in single layer of phospholipids
        phospholipid molecules have hydrophilic heads facing outwards (in contact with water) and hydrophobic tails facing inwards (in contact with non-polar lipids.
- - - - transitory in nature
      - constantly break and reform
- - - - definition: movement of water within spaces of a porous material due to forces of A+C and surface tension.
        
        1) water is drawn through narrow glass tubes
        
        2) change from air-filled to water-filled results in formation of many hydrogen bonds -> release of energy
        
        3) porous solids have large amounts of surface area attracted to water -> can exert strong suction forces through adhesion
        
        importance of adhesion to plants
        
        water adheres to cellulose molecules in cell walls -> when any cell wall drys out, it is automatically rewetted (if there is source of water available)
        
        when water evaporates from cell wall in leaves to atm -> adhesive forces cause water to be drawn out of nearest xylem vessel -> keeps walls moist so they can absorb CO2 for p/s -> generate low pressure that draw water up xylem
        
        xylem vessel becomes air filled -> adhesion b/w water and wall of vessel help vessel to refill with water
- - - - 1) water uptake at roots through osmosis-> adheres to xylem walls ->sucked upwards from roots to leaves along tubular vessels in xylem vessels
      - 2) hydrogen bonds cause cohesion among water molecules -> continuous column of water
      - 3) each column of water is under tension
        
        tension in roots: generated by attractions between solid particles and water
        
        tension in leaves: develops as water is lost by evaporation to atm + due to attraction between water molecules and cell walls of leaf cells
      - 4) water moves upwards as pulling force in leaves > forces in roots
    - - surface of water acts as elastic membrane that shrinks to minimum possible area as water molecules are more attracted to each other by hydrogen bonding than to air particles (surface tension)
        
        surface tension allows objects to float although they are denser -> cohesion b/w water molecules due to hydrogen bonding > attractions between water and floating object
        
        for an object to break through surface of water, many hydrogen bonds must be broken simultaneously, a lot of energy is required (rarely occurs)
      - examples: water striders walk on the water surface with 6 legs, mosquito larvae live just below the surface, hangs from it using siphon