MCB 259: PLANT PHYSIOLOGY 1998, Quiz 2 - September 28


An exergonic reaction is a reaction (D G negative) that
a) needs additional input of energy in order to proceed
b) always proceeds with the release of heat to the environment
c) can proceed and do "useful work" without additional input of energy

Please fill in the blanks
Choose from: / (1) exothermic, exergonic, exotropic, endothermic/ (2) Enthalpy, Entropy, Temperature, activation Energy/ (4) Entropy, Gibbs' Energy or free Energy, pmf/ (5) negative, positive/(6) Enthalpy, Gibbs' free Energy, Entropy, Temperature, activation Energy/ (7) lowered, increased, not changed/
An (1)__________________reaction can proceed and release energy to the environment. If this proceeding reaction does not release heat, this is due to a compensating increase in (2) ________________, which means that the order in the system containing the reactants and products decreases. A chemical reaction can proceed, if the (4)_______________ which is abbreviated as delta G is (5)_______________ for this reaction (taking into account the actual concentrations).
The acceleration of a chemical or biochemical reaction by an enzyme or a catalyst is due to a lowering of the (6)_______________________, delta G is (7)________________by the catalyst.


Give short definitions for symplast and apoplast:



Where is the cellulose synthase located?
A) inside the Golgi apperatus B) as integral membrane protein in the plasmalemma
C) in the cell wall D) inside the ER

Where are the other carbohydrates synthesized (other than cellulose) that form the matrix of the cell wall?
A) inside the Golgi apperatus B) as integral membrane protein in the plasmalemma
C) in the cell wall

What are the energy rich (activated) building blocks that are utilized by the cellulose synthase
A) Glucose-1-phosphate, B) UDP- Glucose, C) Maltose, D) cellobiose

Where are these activated building blocks located?
A) cytoplasm, B) cell wall, C) Golgi vesicles

What correlates with orientation of the deposited cellulose microfibrills
A) the orientation of actin filaments, B) the orientation of the spindle apparatus
C) the orientation of microtubuli, D) the orientation of the preprophase band.

The intercellular spaces between the cell walls of neighboring cells are filled with
A) water B) gas C) depends (water only in water logged soil in plants not adapted to this condition)

Many enzymatically catalyzed reactions can be described by the so called Michaelis-Menten kinetics. These kinetics describe
a) the saturation in the velocity of catalysis with increasing substrate concentrations
b) the time dependence of an enzymatic reaction
c) the rate of free energy dissipation during a reaction as a function of the reaction coordinate

The Michaelis Menten constant gives the
A) maximum velocity of the reaction
B) the substrate concentration at which the maximum turnover is reached
C) the substrate concentration at which half of the maximum turnover is reached