Page 130 - Science Course 1 (Book 1)

Mo4-L4a: How Do Plants Respond to Environmental Stimuli?

Growth away from a stimulus is considered negative.
Key Concept

How Do Plants Respond to
Environmental Stimuli?
What types of environment stimuli do plants
respond to? Give three (3) examples.

The growth of a plant toward or away from light is a
tropism called phototropism
Auxin

Photoperiodism is a plant’s response to the number
of hours of darkness in its environment.

Plants that flower when exposed to less than 10-12
hours of darkness are called long-day plants.

The response of a Short-day plants require 12 or more hours of
plant to touch is called darkness for flowering to begin.
a thigmotropism
Day-neutral plants flower when they reach maturity
and the environmental conditions are right.
24

18 6
Special structures
that respond to
12
touch, called tendrils, Short day plant
can wrap around or
cling to objects. Day length less than 12 hrs for flowering
24

18 6
The response of a
plant to gravity is
called gravitropism. 12
Long day plant
Stems grow away Day length more than 12 hrs for flowering
from gravity, while 12
roots grow toward
gravity
18 6

12
Natural day plant
Day length immaterial than 12 hrs for flowering
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