MCB 259: PLANT PHYSIOLOGY 1998,

Additional questions and answers

Under what conditions do you expect lettuce seeds to germinate on wet filter paper (more than one answer is correct)?
- constant white light,
- constant red light,
- constant far red light,
- one 4 min. pulse of red light,
- one 4 min. pulse of red light followed by a 4 min. pulse of far red light,
- a 4 min. pulse of red light followed by a 4 min. pulse of far red light followed by a 4 min. pulse of red light.

Which form of phytochrome absorbs far red light? Pfr or Pr
Which form of phytochrome is usually the effector? Pfr or Pr
Which form is the only one that is present in etiolated tissues? Pfr or Pr
Which form of phytochrome is the one synthesized in the absence of light? Pfr or Pr

A short day plant (e.g. Kalanchoe blossfeldiana) that would start flowering, when the light period is below 11 hours (>13 hours dark period) is grown under inducing conditions (i.e. 8h light 16h dark), however, in the middle of the dark period light pulses are given. What results do you expect from:
- no light pulses during the dark period --> flowering / no flowering
- 1 min. red light during the dark period --> flowering / no flowering
- 1 min. red light followed by 1 min. far red light during the dark period --> flowering / no flowering

A long day plant that would start flowering, when the light period is above 11 hours (<13 hours dark period) is grown under a cycle of 10h light - 14h dark. In the middle of the dark period light pulses are given. What results do you expect:
- no light pulses during the dark period --> flowering / no flowering
- 1 min. white light during the dark period --> flowering / no flowering
- 1 min. red light during the dark period --> flowering / no flowering
- 1 min. red light followed by 1 min. far red light during the dark period --> flowering / no flowering

A mutant of a lettuce variety that normally flowers under long day conditions no longer bolts and flowers under inducing conditions. What phytohormone would you use to induce flowering (and bolting) in this mutant? GA

You hang a 2inch long piece from a stem (twig) of a willow into a moist and dark chamber. If you hang the twig bottom up,
A) the part of the twig that is at the bottom in the chamber will sprout roots (gravitropic response)
B) the part of the twig that is at the bottom in the chamber will sprout shoots, because it corresponds to the physiological top
C) without external addition of phytohormones nothing will grow

What is the name of the tissue in wheat seeds that in the presence of gibberellins releases amylase activity?
Aleuron layer

What is the name of the tissue in the seeds of grasses that secrets gibberellins into the endosperm? Scutellum

List some characteristics that distinguish an etiolated from a light grown seeding:

cotelydons remain closed, hook doesn't stretch, no anthocyan accumulation in epidermis, less root hairs, more hypocotyl elongation