water as the medium for life
first cells originated in water
remains medium in which most processes of life occur
why are there hydrogen bonds?
consequence of the polar covalent bonds within water
why covalent bonds in water
unequal sharing of electrons
why is there unequal sharing of electrons
oxygen has more electronegativity than hydrogen so electrons sit closer to oxygen
charges in water molecule
hydrogen partial positive
oxygen partial negative
cohesion
water molecules stick to other water molecules
why/how cohesion occurs
hydrogen bonds
usually weak but because of so many they because strong
consequences for organisms due to cohesion
transport of water in xylem
water surfaces as habitats due to effect known as surface tension
adhesion
water molecules stick to other surfaces that are polar or charged
impact of adhesion on organisms
capillary action in soil and plant cell walls
structure of water
H2O
solvent
water can dissolve many organic and inorganic substances that have charged or polar regions
hydrophilic
water loving
substances that dissolve in water and water adheres to
polar substances
hydrophobic
water fearing
non polar
lipids
buoyancy
the upward force exerted by a fluid in the opposite direction of the weight of the object. density lower than liquid it will float, if density is higher it will sink
viscosity
how resistant a fluid is to deformation
how think a liquid is
thermal conductivity
how readily a fluid conducts heat
heat conducts fast in high thermal and slow in low thermal conductivity
specific heat capacity
how much energy is required to raise one unit of mass by one unit of temperature
greater capacity greater energy needed to raise temp
ring tailed seal adaptions
Blubber:
More buoyant
Doesn't compress under pressure
Low thermal conductivity reduces heat loss
Heavy
Harder to move on land
Streamlined body shape:
Reduce drag in water (viscosity)
Feet at rear of body - reduces drag
Webbing between feet - more surface area to push through water
Shape and location of feet make it harder to move on land
black throated loon adaptations
BOUYANCY:
Thicker bones (most birds have hollow bones):
Reduce buoyancy, allows them to dive deep enough to hunt prey
Larger air sacks to control buoyancy, inflate or deflate to increase or decrease buoyancy
Heavier body
More difficult to achieve and maintain height
Require large body of water to launch from
VISCOSITY:
Large webbed feet:
Propel in water
Much smaller than wings to fly
Streamlined shape:
Reduce drag in water (more viscos than air)
Legs and feet at rear, reduces drag
Secrete a hydrophobic oil on their feathers, further reduces drag
Short wings for body shape:
Reduce drag in water
Harder to achieve flight
THERMAL CONDUCTIVITY
Thick layer of down feathers close to their body
Trap air to keep body warm in cold water, creates barrier of air
Down feathers are covered by harder, tightly packed contour feathers
Forms impermeable seal against water
Preening gland on its rump which excludes oil
Preens contour feathers with this oily (hydrophobic) secretion, increasing their waterproofing