MCB 259: PLANT PHYSIOLOGY 1998, Quiz 9 - December 4
Name (please print):


Under what conditions does the production of N2 from other N-containing species occur in soils?

What is the name of this process (see question 2 for possible names)?

How is the enzymatic reduction of N2 to 2 NH4+ usually called?
A) Nitrification, B) Ammonification, C) Nitrogen fixation D) Nitrate assimilation, E) Denitrification

Which group of organisms contains members that can reduce N2 to 2 NH4+.
Eukaryotes, Fungi, Plants, Prokaryotes, Animals

"Why" do some cyanobacteria heterocysts?
A) these cells do not perform photolysis of water, therefore the Nitrogenase is not damaged by O2
B) these thick walled cells are able to survive harsh conditions and function as spores
C) the thylacoids in these cells function as grana thylacoids, the separation of the two photosystems into separate cells prevents spilling over of energy from PSI to PSII

What is the name of the bacteria that form the root nodules with legumes?

List the names of at least two other organisms (or groups of organisms) that are able to fix nitrogen (in case of a symbioses between eukaryote and prokaryote also give the name of the eukaryote):

 What are the functions of leghemoglobin? (two)

What is a lectin?
A) A protein that binds specific carbohydrates
B) A protein that reduces free oxygen levels
C) A plant antibody that is important for plant immunity

Which biochemical reactions are termed nitrate assimilation?

How is sucrose transported from the apoplast into the cells of the phloem complex?
A) via a sucrose pumping ATPase
B) via a sucrose/proton cotransport
C) only after cleavage into monomers can the hexoses be taken up via a hexose/proton cotransport
D) via a sucrose/proton antiport

The pressure flow theory of phloem transport was first formulated by
a) Liebig, b) Buddenbrock, c) Münch, d) Pfeffer

According to the pressure flow theory the difference in hydrostatic pressure between source and sink is generated by
A) the difference in osmotic pressure,
B) the P protein in the pores of the sieve plates
C) the drop in electrical potential across the sieve plates (electroosmosis)

Describe a "cool" experiment that suggests that the driving force for Phloem transport is not generated at the sieve plates.


What are P-proteins, what is its function?


According to the modern version of the pressure flow theory which process leads to the more negative Y p in the source part of the phloem?
a) synthesis of sucrose,
b) loading of the phloem with sucrose
c) cleavage of starch

Which biochemical reaction is catalyzed by Invertase? (give the names of substrate, products and indicate what happens to this substrate)