Chapter Introduction
Lesson 1 Energy
Processing
in Plants
Lesson 2 Plant
Responses
Chapter Wrap-Up
What processes enable
plants to survive?
What do you think?
Before you begin, decide if you agree or
disagree with each of these statements.
As you view this presentation, see if you
change your mind about any of the
statements.
Do you agree or disagree?
1. Plants do not carry on cellular
respiration.
2. Plants are the only organisms that
carry on photosynthesis.
3. Plants make food in their underground
roots.
Do you agree or disagree?
4. Plants do not produce hormones.
5. Plants can respond to their
environments.
6. All plants flower when nights are
10–12 hours long.
Energy Processing in Plants
• How do materials move inside plants?
• How do plants perform photosynthesis?
• What is cellular respiration?
• How are photosynthesis and cellular
respiration alike, and how are they
different?
Energy Processing in Plants
• photosynthesis
• cellular respiration
Materials for Plant Processes
• Xylem and phloem—the vascular
tissue in most plants—transport
materials throughout a plant.
• Water flows inside xylem to all parts of
a plant.
• Most plants make their own food;
a liquid sugar that moves out of foodmaking cells, enters phloem, and flows
to all plant cells.
Materials for Plant Processes (cont.)
Carbon dioxide, oxygen, and water vapor
pass into and out of a plant through tiny
openings in leaves.
How do materials move
through plants?
Photosynthesis
Photosynthesis is a series of chemical
reactions that convert light energy, water,
and carbon dioxide into the food-energy
molecule glucose and give off oxygen.
photosynthesis
from Greek photo–, means “light”;
and synthesis, means “composition”
Photosynthesis (cont.)
• Two types of mesophyll cells inside a
leaf contain chloroplasts, the organelles
where photosynthesis occurs.
• Near the top surface of the leaf are
palisade mesophyll cells, which are
packed together.
• Spongy mesophyll cells have open
spaces between them, and gases
needed for photosynthesis flow through
the spaces.
Photosynthesis (cont.)
• In the first step of photosynthesis, plants
capture the energy in light.
• This occurs in chloroplasts, which
contain plant pigments.
• Chlorophyll, the most common plant
pigment, is necessary for
photosynthesis.
Photosynthesis (cont.)
• Sugars are made in the second step of
photosynthesis.
• In chloroplasts, carbon dioxide and water
are broken down and, using energy
stored in chlorophyll, form sugar
molecules.
Photosynthesis (cont.)
What are the two steps of
photosynthesis?
Cellular Respiration
• Cellular respiration is a series of
chemical reactions that convert the
energy in food molecules into a usable
form of energy called ATP.
• Glucose molecules break down during
cellular respiration.
• Plants produce sugar, but without
cellular respiration, plants could not
grow, reproduce, or repair tissues.
Cellular Respiration (cont.)
What is cellular respiration?
Cellular Respiration (cont.)
• Most plants, some protists, and some
bacteria carry on photosynthesis.
• Most organisms carry on cellular
respiration.
• Life on Earth depends on a balance of
these two processes.
Cellular Respiration (cont.)
How are photosynthesis and
cellular respiration alike, and how
are they different?
• Materials that a plant requires to
survive move through the plant in the
vascular tissue, xylem and phloem.
• Plants can make
their own food by
using light energy,
water, and carbon
dioxide.
• The products of
photosynthesis
are the reactants
for cellular
respiration.
Which term refers to the
organelles where photosynthesis
occurs?
A. palisade mesophyll cells
B. chlorophyll
C. chloroplasts
D. spongy mesophyll cells
Which process breaks down
glucose molecules?
A. cellular respiration
B. light energy capture
C. first step of photosynthesis
D. second step of photosynthesis
Which have open spaces between
them that gases flow through?
A. spongy mesophyll cells
B. palisade mesophyll cells
C. chloroplasts
D. chlorophyll
Do you agree or disagree?
1. Plants do not carry on cellular
respiration.
2. Plants are the only organisms that
carry on photosynthesis.
3. Plants make food in their underground
roots.
Plant Responses
• How do plants respond to
environmental stimuli?
• How do plants respond to chemical
stimuli?
Plant Responses
• stimulus
• tropism
• photoperiodism
• plant hormone
Stimuli and Plant Responses
• Stimuli are any changes in an
organism’s environment that cause a
response.
• A plant responds to light by growing
toward it.
Environmental Stimuli
• A tropism is a response that results in
plant growth toward or away from a
stimulus.
• When the growth is toward a stimulus,
the tropism is called positive.
• Growth away from a stimulus is
considered negative.
The growth of a plant toward or away from
light is a tropism called phototropism
Environmental Stimuli (cont.)
tropism
from Greek tropos, means “turn”
or “turning”
Environmental Stimuli (cont.)
• The response of a plant to touch is called
a thigmotropism.
• Special structures that respond to touch,
called tendrils, can wrap around or cling
to objects.
Environmental Stimuli (cont.)
• The response of a plant to gravity is
called gravitropism.
• Stems grow away from gravity, while
roots grow toward gravity.
Environmental Stimuli (cont.)
What types of environmental
stimuli do plants respond to?
Give three examples.
Environmental Stimuli (cont.)
• 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.
Environmental Stimuli (cont.)
• Short-day plants require 12 or more
hours of darkness for flowering to begin.
• Day-neutral plants flower when they
reach maturity and the environmental
conditions are right.
The number of hours of darkness
controls flowering in many plants.
Chemical Stimuli
• Plant hormones are substances that act
as chemical messengers within plants.
• Auxins are hormones
responsible for
phototropism.
• They cause the cells
on the dark side of
the plant’s stem to
grow longer.
Chemical Stimuli (cont.)
• The plant hormone ethylene helps
stimulate the ripening of fruit.
• Ethylene is a gas that can be produced
by fruits, seeds, flowers, and leaves.
How do plants respond to the
chemical stimuli, or hormones,
auxin and ethylene?
Chemical Stimuli (cont.)
• Rapidly growing areas of a plant, such
as roots and stems, produce gibberellins,
which increase the rate of cell division
and cell elongation.
• Root tips produce cytokinins, a hormone
that increases the rate of cell division
and, in some plants, slows the aging
process of flowers and fruits.
Humans and Plant Responses
• Humans make plants more productive
by using plant hormones.
• Some crops now are easier to grow
because humans understand how plants
respond to hormones.
• Plants respond
to stimuli in their
environments in
many ways.
• Photoperiodism occurs in long-day
plants and short-day plants. Dayneutral plants are not affected by the
number of hours of darkness.
• Plant hormones
are internal
chemical stimuli
that produce
different
responses in
plants.
Which term refers to the growth
of a plant toward or away from
light?
A. phototropism
B. photoperiodism
C. gravitropism
D. thigmotropism
Which of the following helps
stimulate the ripening of fruit?
A. auxins
B. cytokinins
C. ethylene
D. tendrils
Which refers to special plant
structures that respond to touch?
A. roots
B. stems
C. leaves
D. tendrils
Do you agree or disagree?
4. Plants do not produce hormones.
5. Plants can respond to their
environments.
6. All plants flower when nights are
10–12 hours long.
Key Concept Summary
Interactive Concept Map
Chapter Review
Standardized Test Practice
Plants survive by
maintaining
homeostasis and
responding to stimuli.
In addition, they
acquire the energy
they need for life
processes through
photosynthesis and
cellular respiration.
Lesson 1: Energy Processing in Plants
• The vascular tissues in most plants, xylem and
phloem, move materials throughout plants.
• In photosynthesis, plants
convert light energy, water,
and carbon dioxide into the
food-energy molecule glucose
through a series of chemical
reactions. The process gives off oxygen.
• Cellular respiration is a series of chemical reactions
that convert the energy in food molecules into a
usable form of energy called ATP.
• Photosynthesis and cellular respiration can be
considered opposite processes of each other.
Lesson 2: Plant Responses
• Although plants cannot move from one place to
another, they do respond to stimuli, or changes in
their environments. Plants respond to stimuli in
different ways. Tropisms are
growth responses toward or
away from stimuli such as
light, touch, and gravity.
Photoperiodism is a plant’s
response to the number of
hours of darkness in its
environment.
• Plants respond to chemical stimuli, or plant
hormones, such as auxins, ethylene, gibberellins,
and cytokinins. Different hormones have different
effects on plants.
Carbon dioxide, oxygen, and water
vapor pass into and out of a plant
through which part of a plant?
A. leaves
B. phloem
C. roots
D. xylem
Water flows to all parts of a plant
in which of these?
A. xylem
B. phloem
C. chloroplasts
D. chlorophyll
Which term refers to a response
that results in plant growth
toward or away from a stimulus?
A. photoperiodism
B. photosynthesis
C. stimuli
D. tropism
When the growth is toward a
stimulus, what is the tropism
referred to as?
A. negative
B. photoperiodism
C. photosynthesis
D. positive
Which acts as chemical
messengers in plants?
A. hormones
B. stoma
C. tendrils
D. xylem
Which term refers to a series of
chemical reactions that convert light
energy, water, and carbon dioxide into
the food-energy molecule glucose?
A. cellular respiration
B. photosynthesis
C. xylem
D. phloem
Where does the first step of
photosynthesis occur?
A. xylem
B. phloem
C. mesophyll cells
D. chloroplasts
Which term describes any changes
in an organism’s environment that
cause a response?
A. tropism
B. gravitropism
C. phototropism
D. stimuli
Short-day plants require how
many hours of darkness for
flowering to begin?
A. 12 or more
B. 10 to 12
C. 8 to 10
D. less than 8
A growing ivy plant comes into
contact with a brick building and
begins to grow up the building.
What is this response?
A. gravitropism
B. photoperiodism
C. phototropism
D. thigmotropism