# 5.4: Enrichment

Difficulty Level: At Grade Created by: CK-12

## Enrichment 4-1: Teacher Activity Notes

Transport of Materials-Exploring Diffusion

### PLAN

Summary

Students observe the diffusion of potassium permanganate \begin{align*}(KMnO_4)\end{align*} crystals and water in a graduated cylinder.

Objectives

Students:

\begin{align*}\checkmark\end{align*} describe what happens when several crystals of potassium permanganate are placed at the bottom of a column of water in a graduated cylinder.

\begin{align*}\checkmark\end{align*} explain the effect of stirring on the rate of diffusion.

\begin{align*}\checkmark\end{align*} explain the effect of heating or cooling on the rate of diffusion.

Student Materials

• Activity Guide
• Activity Report

Teacher Materials

• Activity Guide
• Two \begin{align*}50-1,000 \ ml\end{align*} (milliliter) graduated cylinders
• One 2-foot-long piece of clean, dry glass tubing with an internal diameter of about \begin{align*}3 \ mm\end{align*}
• 1 container of potassium permanganate \begin{align*}(KMnO_4)\end{align*} crystals
• Water

Obtain the \begin{align*}KMnO_4\end{align*}, graduated cylinders, and glass tubing. If you don't have these available, they can be borrowed from the science department of your local high school. Or they can be ordered from a scientific supply house.

Carolina Biological Supply Company, 2700 York Rd., Burlington, NC 27215. Call 1-800-334-5551.

Estimated Time

20 minutes to set up the demonstration. Setup can be done before class. 5-10 minutes each period over several days. Allow enough time for students to observe the diffusion.

Interdisciplinary Connection

Math Tables and rate determination of diffusion could be completed in math class.

Prerequisites and Background Information

SAFETY CAUTION: Potassium permanganate is poisonous. Be sure that students do not come in contact with it at any time.

Diffusion can be defined as the movement of materials from a region of greater concentration to a region of lesser concentration due to random motion. The energy required for this movement comes from molecular motion of the materials involved. This energy is available to move materials in systems above \begin{align*}-273^\circ C\end{align*}. Diffusion will continue as long as there is a difference in concentration and molecular motion within the system. Diffusion will stop when equilibrium is reached. Once equilibrium is reached, although diffusion stops, molecular motion continues.

Temperature is a net measurement of the molecular motion of the substances in a given system. For example, in an ice cube, water molecules are vibrating as they would in any solid. In liquid water, molecules are moving slowly and randomly. In water vapor, a gas, water molecules are moving rapidly.

Altering the rate of molecular motion can change the rate of diffusion. Molecular motion can be increased by adding more energy to the system in the form of heat energy (raising the temperature) or mechanical energy (stirring). Removing heat from the system (cooling) can slow the rate of diffusion.

Also, the nature of the substance determines its rate of diffusion. For example, perfume diffuses more rapidly than motor oil.

### IMPLEMENT

Steps 1-4 If you set this demonstration up in advance, you may want to encourage students to try to explain how you put the potassium permanganate at the bottom of the cylinder. Take a second cylinder, fill it with water, and drop some crystals into the water. These crystals will dissolve and diffuse on the way down to the bottom.

The rate of diffusion also can be influenced by concentration. For example, you can change the rate by increasing or decreasing the substance added or by increasing or decreasing the amount of liquid in the system.

You may wish to do the demonstration at different temperatures, with varying concentrations or amounts of mechanical energy (stirring). Encourage students to record the time required for diffusion under different conditions and to make a drawing, table, or graph of the results.

• It is important that the glass tubing is dry.
• It is best to select two or three medium-size crystals of potassium permanganate.

Step 5 You and your students should see a clearly distinct band of the purple dye at the bottom of the cylinder. Over a period of several days, have students observe the process of diffusion. Have them record their observations each day. The size and number of crystals will influence the time necessary for diffusion to reach equilibrium.

### ASSESS

Use the observations of the diffusion of potassium permanganate \begin{align*}(KMnO_4)\end{align*} crystals and water in a graduated cylinder and the written responses on the Activity Report to assess if students can:

\begin{align*}\checkmark\end{align*} describe what happens when potassium permanganate crystals are placed at the bottom of a column of water in a graduated cylinder.

\begin{align*}\checkmark\end{align*} explain the effect of stirring on the rate of diffusion.

\begin{align*}\checkmark\end{align*} explain the effect of heating or cooling on the rate of diffusion.

\begin{align*}\checkmark\end{align*} explain the effect of concentration on the rate of diffusion.

## Enrichment Activity 4-1: Transport of Materials-Exploring Diffusion – 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. Explain the process of diffusion.
2. Draw the apparatus.
3. Describe the water in the apparatus. \begin{align*}\text{Day} \ 1 && \text{Day} \ 2 && \text{Day} \ 3 && \text{Day} \ 4\end{align*}
4. How long did the diffusion process take to reach equilibrium?

## Enrichment 4-1 Activity Guide: Transport of Materials-Exploring Diffusion (Student Reproducible)

Introduction

SAFETY CAUTION: Potassium permanganate is poisonous. Be sure that you do not come in contact with it at any time. Because of the poisonous nature of potassium permanganate, it is recommended that this Enrichment be done as a whole-class demonstration.

The diffusion of potassium permanganate \begin{align*}(KMnO_4)\end{align*} crystals in water can be used as a colorful (purple) and simple demonstration.

In this demonstration, your teacher places a few crystals of \begin{align*}KMnO_4\end{align*} at the bottom of a column of pure water in a graduated cylinder. The diffusion of the \begin{align*}KMnO_4\end{align*} is easily observed as it diffuses throughout the column of water.

Predict what will happen to the crystals when placed at the bottom of the cylinder of water and how long it will take for equilibrium to be reached.

Describe why and how the process of diffusion occurs.

Procedure

Step 1 Fill two graduated cylinders \begin{align*}(50-1,000 \ ml)\end{align*} with water. One cylinder will serve as a control. The potassium permanganate \begin{align*}(KMnO_4)\end{align*} will be placed at the bottom of the other. Discuss the role of controls in good experimental design.

Step 2 Select a 2-foot-long piece of clean, dry glass tubing with an internal diameter of about \begin{align*}3 \ mm\end{align*}. The teacher places a thumb over one end of the tube and puts several crystals of \begin{align*}KMnO_4\end{align*} into the other end of the tube. The teacher inverts the tube allowing the crystals to fall down to the other end of the glass tube where the teacher's thumb is positioned.

Step 3 The teacher's thumb is tight against one end of the tube while it is placed into the graduated cylinder. It is important that the cylinder is tipped slightly without spilling the water as the tube is placed carefully into the cylinder. The end of the tube comes into contact with the bottom of the cylinder.

Step 4 Once the tube is placed on the bottom of the cylinder, the cylinder is returned to an upright position to allow the crystals to fall to the bottom of the tube. The teacher quickly removes the tube from the cylinder without removing his/her thumb from the end of the tube.

Step 5 Within a minute, you should see a clearly distinct band of the purple dye at the bottom of the cylinder. Over a period of several days, the class can observe the process of diffusion. The size and number of crystals will influence the time necessary for diffusion to reach equilibrium.

## Enrichment 4-1 Activity Report: Transport of Materials-Exploring Diffusion (Student Reproducible)

1. Explain the process of diffusion.

2. Draw the apparatus.

3. Describe the water in the apparatus.

Day 1

Day 2

Day 3

Day 4

4. How long did the diffusion process take to reach equilibrium?

## Enrichment 4-2: Teacher Activity Notes

Chemical Digestion Simulation

### PLAN

Summary

In this activity students simulate the chemical digestion of food in the mouth, stomach, and small intestine by moving models of nutrients through the digestive tract while simulating the action of digestive enzymes on them.

Objectives

Students:

\begin{align*}\checkmark\end{align*} simulate the action of the digestive enzymes on carbohydrates, fats, and proteins in the mouth, stomach, and small intestine.

\begin{align*}\checkmark\end{align*} identify the end products of the chemical digestion of carbohydrates, fats, and proteins and where they are absorbed.

\begin{align*}\checkmark\end{align*} describe what happens to vitamins, minerals, and water in the digestive tract.

Student Materials

• Activity Guide
• Activity Report
• Butcher paper
• Marking pens
• Food nutrient cards (6)
Carbohydrate, Fat, Protein,
Vitamin, Mineral, Water
• Scissors labeled Carbohydrases
• Scissors labeled Proteases
• Scissors labeled Lipases

Teacher Materials

• Torso model or chart of the digestive system
• Samples/charts representing the six food nutrients

Prepare a set of nutrient cards per group or colored \begin{align*}3 \times 5\end{align*} cards or construction paper. 3 pair labeled scissors per team.

Estimated Time

\begin{align*}1 \ \frac{1}{2}\end{align*} to 2 class periods

Interdisciplinary Connections

Music/Band Make musical sounds of digestion.

Language Arts Students can write about the digestive process in a paragraph, poem, or song.

Physical Education Create a dance or a physical game simulating digestion.

Prerequisites and Background

Knowledge of the nutrients that require digestion and the location and action of the digestive enzymes is helpful.

### IMPLEMENT

Introduce Enrichment 4-2 by reviewing with students the composition and end products of carbohydrates, fats, and proteins, as well as digestive enzymes and the locations where they work in the digestive tract.

Steps 1-2 Because of space, you may need to have students complete Step 1 at different times depending on how many groups there are. Monitor student progress at the completion of Step 2.

Steps 3-4 Monitor student progress at the completion of Step 4.

Steps 5-6 Monitor student progress at the completion of Step 6.

Steps 7-11 Monitor student progress at the completion of Step 11.

### ASSESS

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

\begin{align*}\checkmark\end{align*} demonstrate the action of the digestive enzymes carbohydrases, lipases, and proteases on the appropriate nutrients.

\begin{align*}\checkmark\end{align*} identify the end products of the chemical digestion of carbohydrates, fats, and proteins and where they are absorbed.

\begin{align*}\checkmark\end{align*} describe what happens to vitamins, minerals, and water in the digestive tract.

## Enrichment Activity 4-2: Chemical Digestion Simulation – 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. What is the only food nutrient chemically digested in the mouth?
2. Where are the enzymes produced that partially digest this food nutrient in the mouth?
3. What is the general name for these enzymes?
1. What food nutrient is chemically digested initially in the stomach?
2. Where are the enzymes produced that partially digest this food nutrient in the stomach?
3. What is the general name for these enzymes?
1. What food nutrient is chemically digested initially in the small intestine?
2. Where are the enzymes produced that digest this food nutrient in the small intestine?
3. What is the general name for these enzymes?
1. What other food nutrients are chemically digested in the small intestine?
2. Where are the enzymes produced that partially digest these food nutrients in the small intestine?
1. What are the names of the nutrients or molecules that are ready to be absorbed into the wall of the small intestine?
2. What are the two main characteristics of food nutrients in their final form that allows them to be absorbed into the small intestine?
3. What other nutrients are not chemically digested in your digestive tract but are absorbed? Explain.

## Enrichment Activity Guide: Chemical Digestion Simulation (Student Reproducible)

Introduction

What is the purpose of chemical digestion? Where does it take place in your digestive tract? In this activity you simulate the process of chemical digestion of food by enzymes that takes place in your mouth, stomach, and small intestine.

Materials

• Butcher paper
• Marking pens
• Food nutrient cards (6)
Carbohydrate, Fat, Protein
Vitamin, Mineral, Water
• Scissors labeled Carbohydrases
• Scissors labeled Proteases
• Scissors labeled Lipases
• Activity Report

Procedure

Step 1 Have a group member lie down on a large sheet of butcher paper, and have another group member trace his/her body outline with a pencil.

Step 2 Using the map of your digestive tract on page 26, draw the digestive tract to scale within the body outline. Label the mouth, stomach, and small intestine on the digestive tract drawing. Draw and label the salivary glands and pancreas.

Digestion in the mouth

Step 3 Place the cards that represent the six nutrients in the mouth region of the digestive tract drawing.

Step 4 Using a pair of scissors to represent the carbohydrase enzymes from the salivary glands, cut the carbohydrate card (starch) into double units. These double unit pieces represent double sugars.

Digestion in the stomach

Step 5 Move all the nutrient cards and pieces into the stomach region of the digestive tract.

Step 6 Using a pair of scissors to represent the protease enzymes from the stomach, cut the protein card into short pieces of 2-4 units each. These pieces represent short amino acid chains.

Digestion in the small intestine

Step 7 Move all the nutrient cards and pieces into the small intestine region of the digestive tract.

Step 8 Using a pair of scissors to represent the lipase enzymes from the pancreas and small intestine, cut the fat card into individual pieces that represent fatty acids (3) and glycerol. These fatty acids and the glycerol molecule are small and soluble. They can be absorbed into the small intestine (villi) and bloodstream.

Step 9 Using a pair of scissors to represent the carbohydrase enzymes from the pancreas and small intestine, cut the carbohydrate pieces consisting of double units into single units. These single units are glucose molecules that are small and soluble. They can be absorbed into the small intestine (villi) and bloodstream.

Step 10 Using a pair of scissors to represent the protease enzymes from the pancreas and small intestine, cut the protein pieces into smaller pieces that represent individual amino acids. These amino acid molecules are small and soluble and therefore can be absorbed into the small intestine (villi) and bloodstream.

Step 11 You should notice that the nutrients water, vitamins, and minerals are not digested because they are small and soluble and ready for absorption in the small intestine. A lot of the water passes into the colon or large intestine and is absorbed there.

Step 12 Check with your teacher as to cleanup procedures.

Step 13 Discuss with the members of your group the questions on the Activity Report and then record your answers.

## Enrichment 4-2 Activity Report: Chemical Digestion Simulation (Student Reproducible)

1. a. What is the only food nutrient chemically digested in the mouth?

b. Where are the enzymes produced that partially digest this food nutrient in the mouth?

c. What is the general name for these enzymes?

2. a. What food nutrient is chemically digested initially in the stomach?

b. Where are the enzymes produced that partially digest this food nutrient in the stomach?

c. What is the general name for these enzymes?

3. a. What food nutrient is chemically digested initially in the small intestine?

b. Where are the enzymes produced that partially digest this food nutrient in the small intestine?

c. What is the general name for these enzymes?

4. a. What other food nutrients are chemically digested in the small intestine?

b. Where are the enzymes produced that partially digest these food nutrients in the small intestine?

5. What are the names of the nutrients or molecules that are ready to be absorbed into the wall of the small intestine?

6. What are the two main characteristics of food nutrients in their final form that allows them to be absorbed into the small intestine?

7. What nutrients are not chemically digested in your digestive tract but are absorbed? Explain.

## Enrichment 4-3: Teacher Activity Notes

What Happens to the Digested Nutrients in the Small Intestine?

### PLAN

Summary

Students explore the process of absorption and the characteristics of a selectively permeable membrane. They use dialysis tubing as a model of the selectively permeable membrane of the small intestine and investigate which substances pass through it into the bloodstream.

Objectives

Students:

\begin{align*}\checkmark\end{align*} describe how a selectively permeable membrane works and compare it to cell membranes of the intestine.

\begin{align*}\checkmark\end{align*} explain why glucose, but not starch or fiber, passed through the dialysis tubing.

Student Materials

• Activity Guide
• Activity Report
• 2 test tubes in rack; Benedict's solution; Stirring rod; Iodine solution; Hot plate; String (2 \begin{align*}15-cm\end{align*} pieces); Safety goggles; Dialysis tubing \begin{align*}(20 \ cm)\end{align*}; Paper towels; Water; Jar or \begin{align*}500-ml\end{align*} (milliliter) beaker; Eye dropper; Starch solution; Glucose solution; \begin{align*}250 \ ml\end{align*} (milliliter) beaker; Cereal such as shredded wheat

Teacher Materials

• Extra student supplies including test tubes

Order iodine, Benedict's solution, and soluble starch. Obtain dialysis tubing (from local medical supply store, science supply, or hospital). Prepare (or order) the glucose and starch solutions. The glucose solution can be prepared by adding \begin{align*}25 \ ml\end{align*} of corn syrup to \begin{align*}1,000 \ ml\end{align*} of water. The starch solution can be prepared by adding 15 grams of cornstarch to \begin{align*}1,000 \ ml\end{align*} of water.

Estimated Time

One 45-50-minute class period

Prerequisites and Background Information

Knowledge of digestion in the small intestine, the basic principles of diffusion, and the characteristics of a selectively permeable membrane is helpful.

### IMPLEMENT

Introduce Enrichment 4-3 by discussing what a selectively permeable membrane is and how it works.

Steps 1-4 It may be helpful to make controls to review the positive tests for starch and glucose using iodine and Benedict's solution. Demonstrate a positive test for the presence of glucose and starch.

Steps 5-7 Caution students to be very careful using hot plates. Remind them of the importance of wearing safety glasses during lab activities. Remind students to tie back long hair and roll up loose sleeves. Wear goggles as you demonstrate how to heat the Benedict's solution.

Point out to students that the cereal represents fiber that the body cannot digest because of the lack of the appropriate enzymes.

### ASSESS

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

\begin{align*}\checkmark\end{align*} describe and confirm a positive test for glucose and starch.

\begin{align*}\checkmark\end{align*} explain why some substances moved across the selective membrane and others did not.

## Enrichment Activity 4-3: What Happens to the Digested Nutrients in the Small Intestine? – 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. Predict if glucose, starch, or fiber will pass through the membrane of the dialysis tubing. How will you know which ones passed through?
2. Did starch pass through the dialysis tubing? Explain.
3. Did glucose (sugar) pass through the dialysis tubing? Explain.
4. Did fiber, represented by the shredded wheat, pass through the dialysis tubing? Explain.
5. What do the results of this activity tell you about the dialysis tubing membrane? How is the dialysis tubing membrane similar to an intestinal cell membrane (small intestine)?

## Enrichment 4-3 Activity Guide: What Happens to the Digested Nutrients in the Small Intestine? (Student Reproducible)

Introduction

During digestion, food nutrients are converted to a small, soluble molecular form that can pass into the cells of your small intestine and bloodstream. In this activity you investigate a model of a cell membrane and observe the selective process of the absorption of nutrients.

Materials

• 2 test tubes in rack
• Benedict's solution
• Stirring rod
• Hot plate
• Iodine solution
• String (2, \begin{align*}15 \ cm\end{align*} pieces)
• Safety goggles
• Dialysis tubing \begin{align*}(20 \ cm)\end{align*}
• Paper towels
• Water
• Beakers/jars
• Eye dropper
• Starch solution
• Glucose solution
• \begin{align*}250 \ ml\end{align*} beaker
• Cereal such as shredded wheat

Procedure

Step 1 Soak a \begin{align*}20-cm\end{align*} piece of dialysis tubing in water for a few minutes. Gently rub the ends between your thumb and forefinger until the ends separate.

Step 2 Fold one end of the tubing and then tie it tightly with a piece of string, so it will not leak.

Step 3 Fill a beaker or jar \begin{align*}\frac{1}{3}\end{align*} full of a solution of glucose. Add an equal amount of starch solution. Add the contents of 1 or 2 pieces of fiber (shredded wheat) to the solution. Carefully stir to mix the solutions together.

Step 4 Fill the dialysis tubing \begin{align*}\frac{3}{4}\end{align*} full of the starch/sugar solution plus fiber. Tie the dialysis tubing tightly with a piece of string. Place the dialysis tubing in the beaker containing water.

Wait 15 minutes.

Discuss with your partner/group Question 1 on the Activity Report, then record your response.

Your teacher will demonstrate a positive test for the presence of glucose and starch.

After 15 Minutes

Step 5 Transfer four eyedroppers full of the contents of the beaker into a test tube labeled #1. Put a similar amount into a second test tube labeled #2.

Step 6 Add several drops of iodine into test tube #1. If starch is present, the iodine will change in color from red to purple. Discuss with your partner/group Question 2 on the Activity Report, then record your response.

Step 7 Add 2 droppers full of Benedict's solution into test tube #2. Wearing goggles, gently heat test tube #2 in the water bath. If glucose is present, the Benedict's will change in color from blue to orange/brown. Discuss with your partner/group Questions 3 and 4 on the Activity Report, then record your responses.

Step 9 Complete the Activity Report.

## Enrichment 4-3 Activity Report: What Happens to the Digested Nutrients in the Small Intestine? (Student Reproducible)

1. Predict if glucose, starch, or fiber will pass through the membrane of the dialysis tubing. How will you know which ones pass through?

2. Did starch pass through the dialysis tubing? Explain.

3. Did glucose (sugar) pass through the dialysis tubing? Explain.

4. Did fiber, represented by the shredded wheat, pass through the dialysis tubing? Explain.

5. What do the results of this activity tell you about the dialysis tubing membrane? How is the dialysis tubing membrane similar to an intestinal cell membrane (small intestine)?

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