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Activities and Answer Keys

Created by: CK-12

Activity 3-1: Catalysts and Enzymes in Your Life

PLAN

Summary Students conduct experiments to distinguish between a catalyst (manganese dioxide, MnO_2) and an enzyme (catalase). They investigate the action of the enzyme catalase on hydrogen peroxide (H_2O_2) and explore factors that influence enzyme activity.

Objectives

Students:

\checkmark distinguish between a catalyst (manganese dioxide, MnO_2) and an enzyme (catalase).

\checkmark investigate the action of the enzyme catalase on hydrogen peroxide.

\checkmark explore factors that influence enzyme activity.

\checkmark explain the role of enzymes in maintaining homeostasis in cells.

Student Materials

  • Data Table
  • Activity Report
  • Test tubes (5 per team); Test tube rack; Test tube holder; Marking pen/pencil for test tubes; Graduated cylinder; Forceps; Stirring rod; Hydrogen peroxide (H_2O_2-3%); Sand; Manganese dioxide (MnO_2); Wood splints; Paper towels; Goggles for each team member; Liver cell samples (cooked and uncooked)

Teacher Materials

  • Activity Report Answer Key
  • Data Table (Optional: to be used if students do not design their own or as a model)
  • Extra test tubes, splints, hydrogen peroxide, and paper towels should be available.
  • Liver cell samples (uncooked, cooked, and uncooked soaked in vinegar)
  • Test tube brushes at sinks
  • Wooden splints and matches, for demonstration to identify gas bubbles as oxygen

Advance Preparation

Review student pages relating to enzymes.

Gather and prepare necessary lab materials.

Purchase fresh liver from a local butcher preferably one or two days before the activity. Keep refrigerated until use.

Prepare three liver samples, one cubic centimeter in size, for each team.

Each team needs

  • one piece of fresh liver, best prepared on the day of the activity.
  • one piece of fresh liver that has been thoroughly cooked for 5-10 minutes in a microwave. It is recommended that the samples be placed in a small amount of water and covered before microwaving, in order to prevent drying out. Cooked samples can be stored overnight in a refrigerator.
  • one piece of fresh liver that has been soaked overnight in vinegar.

If time is limited, copy Data Table for student use.

Estimated Time One class period

Interdisciplinary Connection

Art Draw a picture or make a model to illustrate how enzymes work.

Prerequisites and Background

Students need some knowledge of how catalysts and enzymes work. They also need to know how to construct a data table and use a graduated cylinder.

IMPLEMENT

Introduce Activity 3-1 by discussing lab safety rules. Remind students to wear safety goggles as they do this activity. Model the use of goggles.

Step 1 You can choose to have students design their own data table. Or you can copy the Data Table on TE page 35 for students to use.

Step 2 For each team, set out lab materials in trays in an area easily accessible to all students. Glass containers can be substituted for test tubes. The containers must have a minimum height of 2'' to allow for the effervescence of oxygen bubbles. Glass baby food jars could be used.

Steps 3-12 Safety Caution: Be sure students keep hydrogen peroxide capped and stored away from fire and heat.

This lab activity can be used in a variety of ways. If you have time, students can complete the entire lab in their groups. This activity can be done in one period or done by section during successive class periods.

If time is limited, consider using Part A as a demonstration and have students complete Part B in lab groups. Another approach is to have lab groups each complete a different section of the experiments and then pool results to share with the class.

Helpful Hints

Students should design their own data tables, if time permits. One example of a student data table is included.

Clean up directions should emphasize the importance of wrapping any pieces of used liver or other solid materials in paper towels for disposal.

Set up stations for washing and cleaning equipment at the end of each class. Include test tube brushes.

For further explorations, invite students to design experiments exploring other factors influencing enzyme activity, such an extreme drop in temperature caused by freezing the liver. They also could investigate what happens when the liver has been subjected to a high pH (alkaline or basic condition).

Extend Activity 3-1 by demonstrating how to identify the released gas as oxygen. Be sure you have a safe area with a water supply for this demonstration. Discuss lab safety rules and model safe lab techniques, making sure to wear goggles during the demonstration.

To carry out this demonstration, use the following procedure.

  • Put 5-10 ml hydrogen peroxide into a clean test tube. Then add a small amount of manganese dioxide. You should see many bubbles given off.
  • Now light a wooden splint with a match and then blowout the fire. While the splint is still glowing, place it into the test tube near the surface of the bubbles.
  • The splint should burst into flame because of the rich oxygen supply produced by the decomposing of hydrogen peroxide. Be careful not to place the glowing splint into the liquid or it will go out.
  • You may want to repeat this demonstration substituting uncooked liver in place of manganese dioxide.

ASSESS

Use the completion of the activity, the written answers on the Activity Report, and the student presentation to assess if students can

\checkmark distinguish between a catalyst (manganese dioxide, MnO_2) and an enzyme (catalase).

\checkmark describe the action of the enzyme catalase on hydrogen peroxide (H_2O_2)

\checkmark distinguish factors that influence enzyme activity (high temperature due to prolonged heating) and pH (prolonged exposure to vinegar, an acid).

\checkmark explain the importance of enzymes in maintaining homeostasis in cells.

Activity 3-1: Catalysts and Enzymes in Your Life – Activity Report Answer Key

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.

Part A

How are a catalyst and an enzyme similar and how are they different?

  1. What is the purpose of using sand in test tube #1?
  2. Manganese dioxide is a nonprotein substance found in nature, but not produced by living cells. Manganese dioxide is an example of a catalyst. Based upon your observations, what is the function of manganese dioxide in test tube #2?
  3. Describe one difference between the catalyst manganese dioxide and the enzyme catalase.
  4. Liver (test tube #3) is composed of cells that produce the enzyme called catalase. How does the action of the enzyme catalase from liver compare with the action of manganese dioxide in test tube #2?
  5. Describe another difference between the catalyst manganese dioxide (test tube #2) and the enzyme catalase (test tube #3).

Part B

What influences enzyme action?

  1. How do the results of test tube #3 (control) compare with those from test tube #4? Use your observations to explain any difference.
  2. How do the results of test tube #3 (control) compare with those from test tube #5? Use your observations to explain any difference.
  3. As a summary of your knowledge of enzymes, explain:
    • what an enzyme is;
    • where enzymes are produced;
    • what an enzyme does;
    • why enzymes are important in cells and in our body; and
    • what some factors are that influence enzyme action.

    You may present this information in the form of a poster, a computer presentation, or another form of your choice.

Activity 3-1: Catalysts and Enzymes in Your Life Data Table Answer Key

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. Sample Observations

Transport of Nutrients: Exploring Diffusion Students design an activity to explore diffusion using items such as perfume, deodorizer spray, and water and food coloring.

What Do You Think?

Considering what happens to red blood cells in different environments, describe what you think would happen if you moved a single-celled organism from its normal freshwater pond to a saltwater environment. What about moving a saltwater single-celled organism to fresh water? Explain.

You and your best friend are in a canoe on a river. Describe the effort you put in to get the boat to move with the current. Suddenly you realize you forgot something on the shore, so you turn around and paddle upstream. Describe your efforts to move against the current. How is this scenario like active and passive transport? Explain.

What Do You Think?

Why do you think it is so important for living things to reproduce and pass on their genetic material? Why is this “the purpose of life”?

Activity 3-2: Cell Division-Double or Nothing

PLAN

Summary Students simulate the process of mitosis using pipe cleaners to represent chromosomes. They compare the cell before and after division to learn that no genetic information is lost during cell division and that each new cell has the same number of chromosomes.

Objectives

Students

\checkmark simulate each stage of mitosis using pipe cleaners to represent chromosomes.

\checkmark identify and explain the sequence of events in mitosis.

\checkmark determine that no genetic information is lost during cell division and each new cell has the same number of chromosomes.

Student Materials

  • Resources 1 and 2
  • Activity Report
  • Crayons or colored pens or pencils (same colors as pipe cleaners if possible)
  • Large paper plates (2)
  • Eight pipe cleaners (2 long of color A, 2 long of color B, 2 short of color A, and 2 short of color B)

Teacher Materials

  • Activity Report Answer Key
  • Additional student supplies
  • Resources 1 and 2 (Optional)

Advance Preparation

  • Collect student materials.
  • Make copies of Resources 1 and 2 if you plan to do the Optional Activity.

Estimated Time One class period

Interdisciplinary Connection

Art Students can illustrate the processes of mitosis on a poster or in a collage.

Prerequisites and Background

Students need to be familiar with the parts of the cell and the process of mitotic cell division.

IMPLEMENT

Steps 1-8 Have students work in pairs. Give one set of student materials to each pair. However, each student should complete his or her own Activity Report.

Monitor student progress to check students' knowledge after each simulated stage of mitosis.

Optional Activity To provide an optional (but recommended) activity to reinforce concepts presented in this activity, use Resource 1 (student procedure) and Resource 2 (chromosome cards). If you choose to do this optional activity, here are some helpful ideas to use.

1. Consider laminating the chromosome cards before students use them.

2. Encourage students to enhance their demonstrations of chromosome card movements with verbal and/or written explanations.

3. Students can summarize what they learned by completing one of the following additional creative activities to share with classmates. They can create a

  • poster.
  • book, with illustrations.
  • poem.
  • computer simulation.

Helpful Hints

  • Check student knowledge after each simulated stage of mitosis.
  • The first teams to demonstrate the correct sequence of mitotic stages can act as “Teacher Assistants” to help other teams.

ASSESS

Use the completion of the activity and written responses on the Activity Report to assess if students can

\checkmark simulate each stage of mitosis.

\checkmark identify the sequence of events in mitosis.

\checkmark determine that no genetic information is lost during cell division and each new cell has the same number of chromosomes.

Activity 3-2: Cell Division-Double or Nothing – Activity Report Answer Key

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. Compare the chromosome number of the parent cell with that of each of the two daughter cells.
  2. Compare the genetic information of the parent cell with that of each of the two daughter cells with single chromosomes.
  3. What is the importance of mitosis to the organism?
  4. You have 46 chromosomes in each of your somatic cells. If you cut your arm, how many chromosomes would be in each newly formed skin cell?
  5. Pretend that you are a double chromosome in the nucleus of a finger cell. Describe in a paragraph your experience going through cell division becoming a new finger cell. Diagram as you did on your Activity Report.

Mitosis in Action

Students create a cartoon, poster, story book, poem, dance, or song or build a model to summarize what they have learned about mitosis.

What Do You Think?

Some single-celled organisms such as an amoeba don't use gamete cells produced by meiosis. Single-celled organisms reproduce through mitosis only. Why might this process be a good way to pass on their genetic material to their offspring? What might be some problems with this method of reproduction?

Review Questions/Answers

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. What are enzymes and why are they important to the cell?
  2. What are the roles of osmosis and diffusion in the cell?
  3. Why do cells divide?
  4. How are mitosis and meiosis similar? How are they different?

Activity 3-1 Data Table: Catalysts and Enzymes in Your Life (Student Reproducible)

Sample Observations
#1.
#2.
#3.
#4.
#5.

Activity 3-1 Report: Catalysts and Enzymes in Your Life (Student Reproducible)

Part A

How are a catalyst and an enzyme similar and how are they different?

1. What is the purpose of using sand in test tube #1?

2. Manganese dioxide is a nonprotein substance found in nature, but not produced by living cells. Manganese dioxide is an example of a catalyst. Based upon your observations, what is the function of manganese dioxide in test tube #2?

3. Describe one difference between the catalyst manganese dioxide and the enzyme catalase.

4. Liver (test tube #3) is composed of cells that produce an enzyme called catalase. How does the action of the enzyme catalase from liver compare with the action of manganese dioxide in test tube #2?

5. Describe another difference between the catalyst manganese dioxide (test tube #2) and the enzyme catalase (test tube #3).

Part B

What influences enzyme action?

6. How do the results of test tube #3 (control) compare with those from test tube #4? Use your observations to explain any difference.

7. How do the results of test tube #3 (control) compare with those from test tube #5? Use your observations to explain any difference.

8. As a summary of your knowledge of enzymes, explain

  • what an enzyme is;
  • where enzymes are produced;
  • what an enzyme does;
  • why enzymes are important in cells and in our body; and
  • what some factors are that influence enzyme action.

You may present this information in the form of a poster, a computer presentation, or another form of your choice.

Activity 3-2 Resource 1: Cell Division-Double or Nothing (Student Reproducible)

Introduction

How much do you know about mitosis? Can you demonstrate your knowledge of mitosis to a friend? Using the instructions below and the chromosome cards, work with a partner to simulate the sequence of events that occur during mitosis. Be sure that you demonstrate events before and after replication of DNA, the sorting of chromosomes, and the cell division resulting in two daughter cells.

Materials

  • Resource 2 (chromosome cards)
  • Activity Report
  • Scissors
  • Tape
  • Large piece of butcher paper to represent the cell

Procedure

Step 1 Put your initials on the back of each card in your deck of 46 cards. This deck represents the diploid number of chromosomes.

Step 2 Place your chromosomes in numerical sequence from autosomal chromosome #1 through #22 and then the X chromosome. Note the characteristic differences in size and position of the centromere and banding patterns among the chromosomes. This double set represents the number of chromosomes you have in each of your body (somatic) cells.

Step 3 Work with a partner who has a different colored set of cards.

Step 4 To represent DNA replication, take sticky tape and tape your partner's set of chromosomes to each of your chromosomes, pairing each homologous pair. For example, you will have green chromosome #1 linked to yellow chromosome #1. The tape represents the centromere. That is the amount of genetic material that you have in a somatic cell just after DNA replication, but before cell division. The difference is that each chromosome is joined at the centromere so that you have two sister chromatids linked together.

Step 5 Line up your chromosomes in the center of the large sheet of construction paper along the same plane (in single-file order). Separate each of the sister chromatids that are taped together. Send one of each pair to each end of the large piece of construction paper. You can see that each half of the construction paper has a complete set of chromosomes.

Step 6 Cut the butcher paper in the middle. Now you have two cells, each with a complete set of 46 single chromosomes. What do you conclude about the overall outcome of mitosis in terms of chromosome content? Is each daughter cell the same?

Activity 3-2 Resource 2: Cell Division-Double or Nothing (Student Reproducible)

Activity 3-2 Report: Cell Division-Double or Nothing (Student Reproducible)

Activity 3-2 Report: Cell Division-Double or Nothing (Student Reproducible)

1. Compare the chromosome number of the parent cell with that of each of the two daughter cells.

2. Compare the genetic information of the parent cell with that of each of the two daughter cells with single chromosomes.

3. What is the importance of mitosis to the organism?

4. You have 46 chromosomes in each of your somatic cells. If you cut your arm, how many chromosomes would be in each newly formed skin cell?

5. Pretend that you are a double chromosome in the nucleus of a finger cell. Describe in a paragraph your experience going through cell division to become a new finger cell. Diagram as you did on your Activity Report.

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