Sunlight + Water + Carbon Dioxide Glucose + Oxygen

[Pages:3]Photosynthesis Reading/Guide

How Plants Feed Themselves:

Name:____________________ Date:__________ Pd:_____

Have you ever wondered how plants feed themselves? Most plants create meals for themselves in the form of sugar. This process is called photosynthesis. The word `photo' means light, and the word `synthesis' means making. Photosynthesis means making food with light.

If we were to put the ingredients for photosynthesis on a recipe card, here is what we would need: water, carbon dioxide from the air, chlorophyll from the cells of green plants, and sunlight for energy. Without these ingredients, plants could not make the sugar they need for food.

Here is how the recipe would work: Photosynthesis begins at the roots of the plant. The roots suck up water from the ground, which travels to the leaves through tubes in the stems of the plant called xylem.

Then carbon dioxide from the air, which is breathed out by animals, is absorbed into the leaves through tiny pores called the stomata. It is then taken to cells inside the leaves. These cells contain a green pigment called chlorophyll. The chlorophyll absorbs energy from the sunlight. Altogether, the overall chemical equation for photosynthesis (below) shows what molecules are needed for the process to work as well as what molecules are produced as a result. As you read through the following sections, keep track of these different molecules.

Sunlight + Water + Carbon Dioxide Glucose + Oxygen

Light Dependent Reactions:

In the first step of photosynthesis, called the light-dependent reactions, energy from the sunlight breaks down the water in the leaves and turns it into oxygen and hydrogen. The plant uses some of the oxygen to help it grow, and some of the oxygen is given off into the air. People and animals use oxygen to breathe. Also, electrons are stripped and carried through an electron transport chain in order to make ATP molecules. These ATP molecules provide the energy necessary to build glucose molecules in the second step of photosynthesis.

The Calvin Cycle:

In the second step of photosynthesis, the Calvin Cycle, energy from ATP molecules is used to combine hydrogen from water with the carbon dioxide inside the cells of the leaves. This process, called "carbon fixation," creates food molecules in the form of sugar (glucose) for the plant. The plant stores the glucose in its leaves, stems, and roots. The sugar, among many other things, helps the plant grow.

Since most living things eat plants, it can be said that photosynthesis is the source of all life. The process of photosynthesis continually regenerates oxygen in our environment. Altogether, the ingredients used in the photosynthesis recipe feed almost all living things on Earth.

Science With Mr. Comerford

Photosynthesis

Photosynthesis Reading/Guide

Name:____________________ Date:__________ Pd:_____

True or False: Mark the place in the article where you find the information about each statement. If a statement is true, mark True. If a statement is false, mark False and write the correct statement in the box.

Statement

1. Plants are capable of creating their own meals

Before T / F

After T / F

Corrected Statement

2. Photosynthesis means "making light"

3. Plants require sunlight to make energy

4. The water plants require comes from their leaves

5. Leaves contain a pigment called chlorophyll which absorbs carbon dioxide

6. Sunlight breaks water molecules in the light reaction

7. The light reactions give off oxygen, which animals can breathe

8. Transporting electrons helps plants make molecules of oxygen

9. Energy from ATP combines hydrogen and carbon to make glucose during the Calvin Cycle

10. Only plants benefit from photosynthesis

Science With Mr. Comerford

Photosynthesis

Photosynthesis Reading/Guide

Name:____________________ Date:__________ Pd:_____

Organize Your Thoughts: Use information from the article to fill in each box in the organizer below.

Name of Photosynthesis

1.

2.

Stage

Main Purpose / Function

Molecules Required (In)

Molecules Produced (Out)

Finish the Picture: Use the terms from the word bank to fill in the diagram below.

Glucose Carbon dioxide (CO2)

Word Bank Light

Oxygen (O2)

Water (H2O) Chlorophyll

Science With Mr. Comerford

Photosynthesis

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download