UNIT 14: EXTERNAL FACTORS

Study Questions  Lecture Outline
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KEY WORDS

Phototropism Diurmal Daffodil
Geotropism Circadian Vernalization
Flavin Zeitgebel Nyctonastic
Amyloplasts Endogenous Pulvinus
Statolith Viability Heliotropism
Thigmotropism Acclimation


STUDY QUESTIONS

UNIT 14: EXTERNAL FACTORS

1 - Proposed pigment which serves as a receptor in phototropism

2 - General term for plant movements which depend on the direction of the
	stimulus

3 - Plant organ which is positively geotropic

4 - Area where auxin accumulates in horizontal stems

5 - Strucutre which has been proposed as a statolith

6 - Inorganic ion which has been associated with geotropic response

7 - Term for the response of plants to touch

8 - Cell structure which has been associated with the control mechanism
    for endogenous rhythms

9 - Term for a rhythm which is approximately 24 hours in duration

10 - Category of plants which produce flowers when the photoperiod is
     greater than the critical value

11 - Flowering (photoperiod) group which includes radishes

12 - Wave length of light which causes the accumulation of PFR

13 - Form of phytochrome which accumulates in sunlight

14 - Form of phytochrome which promotes internode elongation

15 - Form of phytochrome which inhibits germination of light-requiring
     seeds

16 - Form of phytochrome which accumulates after exposure to 660 radiation

17 - Ion which a component of chlorophyll in addition to C and H

18 - Ion which is generally in higher concentrations in green, leafy
     vegetables


LECTURE OUTLINE

UNIT 14: EXTERNAL FACTORS

INFLUENCE OF ENVIRONMENT

A - Tropisms - direction response depends on direction of stimulus

   1 - Types
       a - Photo - IAA migration to dark side - blue sensitive
       b - gravi - (geotropism) -
           (1) IAA accumulates in lower portion
           (2) roots - inhibited, whiforted
           (3) stems - promoted
       c - mediated by -
           (1) calcium ion -
           (2) statoliths - starch (amyloplasts)
       d - thigmo - touch, tendrils
       e - helio - orient to sun's rays


   2 - Circadian rhythms - biological clock
       a - Esso - set by light and dark periods

   3 - Photoperiodism
       a - SD-LD
       b - flash light during dark period

                      light
             P                     Pfr
              R
                        dark


   4 - Phytochrome
       a - seed germination
       b - photomorphogenesis

   5 - Dormancy - seeds and buds

   6 - Nastic movements - do not depend on the direction of the stimulus
       a - sleep movements
       b - Venus fly trap

   7 - Solar tracking


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