Biology (Holt)

Before You Begin

Plants use to produce food.

One product of photosynthesis is oxygen. In

this activity, you will observe the process of

photosynthesis and determine the rate of

photosynthesis for Elodea.

1.Write a definition for the boldface term above.

2.Create a Data Table like the one below.

Procedure

1.Add 450 mL of baking-soda-and-water

solution to a beaker.

2.Put two or three sprigs of Elodeain the

beaker. The baking soda will provide the

Elodeawith the carbon dioxide it needs for

photosynthesis.

3.Place the wide end of the funnel over the

Elodea.The end of the funnel with the small

opening should be pointing up. The Elodea

and the funnel should be completely under

the solution, as shown on the facing page.

4.Fill a test tube with the remaining

baking-soda-and-water solution. Place

your thumb over the end of the test tube.

Turn the test tube upside-down, taking

care that no air enters. Hold the opening

of the test tube under the solution and

place the test tube over the small end of

the funnel. Try not to let any solution leak

out of the test tube as you do this.

photosynthesis

Skills Practice Lab

SKILLS

• Measuring


• Collecting Data


• Graphing

OBJECTIVE

• Measureamount of
  oxygen produced by
  an Elodeasprig.

Observing Oxygen Production

from Photosynthesis

Elodea

114 CHAPTER 5Photosynthesis and Respiration

ChemSafety

ChemSafety

CAUTION: Always

wear safety gog-

gles and a lab apron to protect

your eyes and clothing.

CAUTION: Glassware is

fragile. Notify the teacher

of broken glass or cuts. Do not

clean up broken glass or spills

with broken glass unless the

teacher tells you to do so.

CAUTION: wear dispos-

able polyethlene gloves

when handling any plant. Do

not eat any part of a plant or

plant seed used in the lab.

Wash hands thoroughly after

handling any part of a plant.

Amount of Gas Present in the Test Tube

Days of exposure Total amount of Amount of gas

to light gas present (mm) produced per

day (mm)

0 1 2 3 4 5

MATERIALS

• 500 mL of 5 percent
  baking-soda-and-
  water solution


• 600 mL beaker


• 20 cm long Elodea
  sprigs (2–3)


• glass funnel


• test tube


• metric ruler


• protective gloves