ENERGY PROCESSING IN PLANTSC10L1

CHAPTER INTRODUCTION

What processes enable plants to survive and reproduce?

• 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

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 food-making cells, enters phloem, and flows to all plant cells.

Materials for Plant Processes

Carbon dioxide, oxygen, and water vapor pass into and out of a plant through tiny openings in leaves.

Materials for Plant Processes (cont.)

How do materials move through plants?

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

photosynthesisfrom Greek photo–, means “light”; and synthesis, means “composition”

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.)

Photosynthesis (cont.)

What are the two steps of photosynthesis?

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

Cellular Respiration (cont.)

What is cellular respiration?

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.)

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.