Name:
Date:
Period:
BACKGROUND:
Lucy the Lunch Lady has just started her first day on the job in the
cafeteria of the local middle school. Her boss has given her the
job of making fruit and gelatin salad for the seventh grade lunch
menu. Seeing several pineapples in the kitchen, she decides to
add fresh pineapple to the gelatin. When lunchtime arrives she
opens the refrigerator only to find a gooey mess!
Lucy knows she will need to make gelatin dessert again next
week. She remembers from biology class that the enzymes in
some fruits can break down gelatin. Lucy suspects the pineapple
she added to the gelatin may contain an enzyme that stopped the
gelatin from hardening.
Help Lucy discover if the pineapple is to blame for her disgusting
dessert disaster.
MATERIALS:
Two test tubes, Test tube rack, Fresh pineapple pieces, Hot gelatin (prepared by your teachers),
Masking tape, Marker, Safety glasses, Paper towels for cleanup
PROCEDURE:
Step 1: What change could we make to the liquid gelatin to see if pineapple enzymes would prevent it
from hardening?
OUR PROBLEM: What are the effects of ____________________ on _______________________?
Identify the following:
Control group: ___________________________________________________________________
Independent variable: _____________________________________________________________
Dependent variable: ______________________________________________________________
------------------------------------------------------------ STOP! --------------------------------------------------------------1
Step 2: Hypothesis
What do you know about enzymes? Using your knowledge of enzymes and their effects on
substrates, write a hypothesis.
IF pineapples stop gelatin from hardening, THEN _____________________________________,
------------------------------------------------------------ STOP! --------------------------------------------------------------Step 3: Your teachers have prepared hot gelatin at the front of the classroom. After putting on safety
glasses, each lab group will come to the front of the class and observe the hot gelatin.
(CAUTION LIQUID AND CONTAINER ARE HOT, DO NOT TOUCH!)
Table 1: Qualitative Observations of Gelatin before cooling:
Step 4: What is a quantitative observation that you can we make of the hot gelatin liquid? What kind
of tool would you use to make such a quantitative observation? Using Table 1 as an example, write a
title for this table.
Table 2: ________________________________________________________________________
------------------------------------------------------------ STOP! --------------------------------------------------------------Step 5: Experiment
1. Take two (3) cups. Label them #1, #2 and #3 using the marker.
2. Have your teacher pour 5 ml of hot gelatin into each of your cups (CAUTION CUPS AND
GELATIN WILL BE HOT). Observe the gelatin. Record your qualitative observations below.
3. Cup #1 is your CONTROL GROUP
4. Place three pieces of fresh pineapple into CUP #2.
5. Place three pieces of canned pineapple into CUP #3.
6. When finished raise your hands and your teachers will help you cool your cups.
------------------------------------------------------------ STOP! --------------------------------------------------------------2
Step 6: Gather and Record Your Data
After the cups have cooled, OBSERVE EACH CUP. Use your senses, BUT DO NOT EAT! Record
your information below. Don’t forget to title this table!
Table 3: _________________________________________________________________________
Variable Group
BEFORE COOLING
AFTER COOLING
Cup # 1:
CONTROL
Cup # 2:
FRESH
PINEAPPLE
Cup # 3:
CANNED
PINEAPPLE
Remember you made a quantitative observation before cooling the gelatin. Now, make the same
measurement and record your information below. Don’t forget to title this table!
Table 4: _________________________________________________________________________
Cup Number:
Temperature (C) Before
Cup # 1
Cup # 2
Cup # 3
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Temperature (C) After
Step 7: Analyze Data and Conclusions (Write in complete sentences.)
1. What did you observe or measure about the gelatin before it cooled?
2. Does the data you gathered during the experiment SUPPORT or DISPROVE your hypothesis?
Support your answer with evidence from your experiment?
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3. If gelatin is a kind of substrate and pineapple contains an enzyme that dissolves gelatin, how can
you explain what happened in cup # 2? (You may write or draw what you think happened in the space
below. If you decide to draw what happened, be sure to label your drawing.)
4. Was there a difference in the results in cup #2 and cup #3? Explain why or why not?
5. What do you think Lunch Lady Lucy should do next week to avoid a gooey gelatin disaster?
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