IB Biology SL: Unit 3, Biochemistry

what is a common feature of enzymes?

• they all react with substrates

explain the relationship between temperature and the activity of enzymes

• rise in temp results in increased speed of molecules

• increased frequency of collisions (of molecules)

• therefore increasing the rate of reaction due to greater enzyme activity

• if the temperature is above the optimum temperature, the enzyme will start to denature and change shape

• low temperatures can be insufficient activation energy

When the substrate concentration on rate of an enzyme-controlled reaction reaches a plateau, what does this indicate?

all active sites are occupied by substrate molecules

what does enzyme function depend on?

collisions between substrates and active sites

explain enzyme-substrate specificity

• two models, induced fit and lock & key

• lock & key - illustrates exclusive nature of one specific’s enzyme’s active site per substrate

• induced fit model - illustrates that active site changes to fit substrate better, rather than an arbitrary fixed shape

  • this small change in shape however, maximizes the surface area, therefore increasing the enzyme’s ability to catalyze its reaction.

what allows for movement of water under tension in the xylem?

• cohesion between water molecules allow water to move up the xylem through the natural tension created by the leaf’s surface during transpiration

• adhesion between water molecules and other molecules (xylem wall), which generates tension forces in cell walls

distinguish between the thermal properties of air and water as they relate to the habitat of animals

• specific heat capacity

  • water has HIGH specific heat capacity,
    air has a LOW specific heat capacity

  • stable temp. due to water’s HIGH specific heat capacity allows the ringed seal to live and feed throughout the year

  • the difference in heat capacity results in a fluctuation of temperatures, which freezes the surface of the water, allows the ringed seals to have a habitat under and on top of the ice throughout the year. [temp diff → ice, habitat for ringed seals]

• thermal conductivity

  • air has a HIGH thermal conductivity, the black-throated loons use the trapped air between their feathers to insulate themselves.

  • because of water’s LOW thermal conductivity, ice has insulating properties → ice traps heat underneath

• buoyancy ((doesn’t apply to q))

  • high buoyancy of water forces the loons to compress air and feathers + increase weight to successfully dive (& dec buoyancy)

  • blubber in ringed seals act as buoyancy-aid

• viscosity

  • hydrodynamic shapes of loon and seal move in water easily, loon: webbed feet, seal: flippers

  • air: loon light feathers → no friction

which molecules are produced during the hydrolysis of a triglyceride molecule?

hydrolysis: adding water to make large compounds into smaller molecules

fatty acids & glycerol