C10L1
ENERGY PROCESSING IN PLANTS
CHAPTER INTRODUCTION
What processes enable
plants to survive and
reproduce?
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?
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.