Download - Biology 25.1
25-1 HORMONES AND PLANT GROWTH
Ch. 25 Plant and Responses and Adaptations
HORMONE Substance produced in one part of an
organism that affects another part of the same organism
TARGET CELL Cell that has a receptor for a particular
hormone
PHOTOTROPISM Tendency of plants to grow toward a
source of light
AUXIN Substance produced in the tip of a
seedling that stimulates cell elongation
GRAVITROPISM Response of a plant to the force of
gravity
LATERAL BUD Meristematic area on the side of a stem
that gives rise to side branches
APICAL DOMINANCE Phenomenon in which the closer a bud
is to the stem’s tip, the more its growth is inhibited
HERBICIDE Compound that is toxic to plants
CYTOKININ Plant hormone produced in growing
roots and in developing fruits and seeds
GIBBERELLIN Growth-promoting substance produced
by plants
ETHYLENE Plant hormone that stimulates fruits to
ripen
KEY CONCEPT Plant hormones are chemical
substances that control a plant’s patterns of growth and development, and the plant’s responses to environmental conditions.
KEY CONCEPTS Auxins are produced in the apical
meristem and are transported downward into the rest of the plant. They stimulate cell elongation.
KEY CONCEPTS In plants, cytokinins stimulate cell
division and the growth of lateral buds, and cause dormant seeds to sprout.
KEY CONCEPTS Gibberellins produce dramatic increases
in size, particularly in stems and fruit.
KEY CONCEPTS In response to auxins, fruit tissues
release small amounts of the hormone ethylene. Ethylene then stimulates fruits to ripen.