Unit 12 Flashcards
Stimuli
A change in the environment that causes a reaction by the organism
Plants grow…
Toward the light
Phototropism
Directional plant growth in response to light
Photo means…
Light
Tropism refers to…
Movement of the plant in response to the stimulus
Positive phototropism
Growth toward the light source
Negative phototropism
Growth away from the light source
The shoot system grows…
Toward the light
The root system grows…
Away from the light
Plant’s respond to…
Gravitational force
Gravitropism
Directional plant growth response to gravity: may be positive or negative; also called geotropism
Negative gravitropism
Growth away from the gravitational force; also called geotropism
Positive gravitropism
Growth toward the gravitational force
Geotropism
Directional plant growth response to gravity; may be positive or negative; also called gravitropism
Roots growing away from the light and in the same direction as gravity are more likely to find…
Minerals
Stems growing toward the light and against gravity will receive…
The energy required
Control Systems
Systems within plants that produce definite responses to specific stimuli
Charles darwin documented their findings in his book…
The power of movement in plants
Peter boysen-jensen was trying to determine how…
The tip was communicating with the area of elongation
Area of elongation
An area of cells in the developing plant facing away from the light source, that each elongate in a phototropic response to the light stimulus
Boysen-jensen concluded…
That whatever was responsible for communicating stimulus information from the tip to the area of elongation was able to diffuse through the gelatin
He suggested that the growth response could only be accomplished…
As a result of a chemical moving from the tip to the area of elongation
Holland F.W went was able to isolate this chemical substance has indicated…
The later given name auxin
Auxin
Type of plant hormone that promotes cell growth or elongation
