MCB 259: PLANT PHYSIOLOGY 1998, Quiz 10
1. If you put a piece of tobacco stem on culture medium (no phytohormones added) solidified with agar-agar, what effects on regeneration do you expect from
a) high Auxin concentrations:
b) high Cytokinin concentrations:
c) high Auxin and Cytokinin concentrations:
d) no phytohormones added:
2. In what part of the plant are auxins produced?
A) Root meristems B) Shoot meristems C) Vascular bundles D) Mesophyll cells
3. How is the polarity generated in small regenerating stem pieces (e.g. willow; roots regenerate at the physiological bottom part)?
4. How do increased auxin levels lead to increased cell elongation?
A) Auxin leads to increased proton secretion into the cell wall which in turn leads to a yielding of the cell wall to the turgor pressure.
B) Auxin leads to reorientation of the cellulose fibers (all parallel) to that the cell wall can expand perpendicular to the cellulose fibers
C) Auxin leads to increased cell turgor
5. Which phytohormones are overproduced in plant tumors that have been caused by Agrobacterium?
a) ethylene and auxin, b) auxin and cytokinin, c) cytokinin and gibberellins d) gibberellin and auxin
6. How do the Agrobacteria cause this phytohormone overproduction?
a) Agrobacteria provide phytohormone precursors that the plant turns into functioning hormone analogues
b) they transform plant cells with genes that encode enzymes that synthesize the phytohormones.
c) the agrobacteria synthesize and secrete phytohormone
7. How come that auxin is always transported from top to bottom in a plant?
A) The cell wall is more acidic on the top of each cell
B) The auxin efflux carrier is located at the bottom of each cell
C) The electrical transmembrane potential does not allow the negatively charged form (IAA-) to enter the cells; therefore, the protonated form is always entering at the top of the cell and leaving at the bottom.
8. Which phytohormone is the reason for the finding that one rotten apple spoils the whole lot?
9. The ancient Chinese are reported to have burned incense in fruit storage places to induce ripening. What might be the physiological basis for this procedure?
10. List five Phytohormones and at least two processes in which this phytohormone is involved:
11. What is the name of the class of mutants that change the fate of a phytomer differentiation (e.g. flowers with stamens instead of carpels) ?
a) homomeric mutants
b) homeotic mutant
c) pic mutant (phytomer identity crisis)
12. Draw a picture of a wheat seed, label and/or otherwise explain what is the coleoptile, what is the scutellum, what is the aleurone, what is the endosperm? Indicate the place where GA is released into the endosperm, and where amylase is released.