Which of these external stimuli produce movement of a plant toward light?
positive phototropism
The germinating corn seed pictured below is displaying
(center of earth)
positive gravitropism.
________ is often referred to as the "stress" hormone since it initiates and maintains seed and bud dormancy.
Abscisic acid
Removing the top of a plant to create fuller growth involves which of the following hormones?
auxins
Which of the following is NOT a physiological change related to photoperiodism?
root branching
The general sequence by which a plant responds to external stimuli is
reception-transduction-cellular response.
Which of the following plant hormones is associated with the closure of stomata when a plant experiences water stress?
abscisic acid
A hormone that causes cell division and is found in coconut milk and in dividing root tissue is
cytokinin.
The vine in the picture below is displaying
thigmotropism.
Horticulturists often use ________ and other growth regulators applied as a paste to plant cuttings to stimulate root formation.
Auxin
Which of the following plant hormones was discovered in infected rice seedlings that grew extremely tall and slender with "foolish seedling disease"?
gibberellins
Which of the following plant hormones stimulates the ripening of fruit and inhibits plant growth?
ethylene
Plants could readily develop seasonal responses for flowering based on temperature changes but have "elected" through evolution to manage their rhythms based on a comparison of daylight and darkness. Why has the day-night ratio system been selected?
Temperatures fluctuate widely across seasons and from year to year, but photoperiod comparisons are a more reliable indicator of season.
Which of the following events will occur in response to gravitrophism?
Because of the change in the plants positions it will have sediments of statoliths (amyloplasts containing starch granules) settle towards the lower side of the stems and rots and come into contact with the cytoskeletal elements.