Mealworm Puzzle With sample Solutions

An experimenter wanted to test the response of mealworms to light and moisture.  To do this he set up four boxes as shown in the diagram below.  He used lamps for light sources and constantly watered pieces of paper in the boxes for moisture.  In the center of each box he placed 20 mealworms.  One day later he returned to count the number of mealworms that had crawled to the different ends of the boxes.

The diagrams show that mealworms resond to (response means move toward or away from):

A. light but not moisture

B. moisture but not light

C. both light and moisture

D. Neither light nor moisture

Explain your choice.

Student sample answers

Juan Diego

1. “No definite pattern was followed by the mealworms.”

Norma Kuhn

1. “Because even though the light was moved in different places, the mealworms 

       didn’t do the same things.

Colleen Wiz

A.  “They usually went to the end of the  box with the light.”

Jackie Haun

1. “Because there are 17 worms by the light and there are only 3 by the moisture.”

Harold O’Kelly

1. “Because in all situations, the majority go where there’s light. Wetness doesn’t

        seem to make a difference.”

Barbara Danour

      C. “Boxes I and II show they prefer dry and light to wet and dark, Box IV eliminates 

        dryness as a factor, so they do respond to light only.  Box III shows that wetness  

        cancels the effect of the light, so it seems they prefer dry.  (It would be clearer if

        one of the boxes was wet-dry with no light).”

David Kentin

C.  “ When the light was on the dry side they all crowded to the dry side.  When it 

         was on  the wet side, an equal amount went to each side.”

Alexa Johnson

C.   “In experiment 3 the mealworms split half wet, half dry.  So it’s safe to assume

        that light was not the only factor involved.”

Deloris Bates

1. “I, II, and IV show that mealworms seem to like the light, but in III they seem to 

       be equally spaced. This leads one to believe that mealworms like the dryness and 

       the reason in pictures III and IV they are by the light is because of the heat that

       the light produces which gives a dryness effect.”

John Blake

1. “The Mealworms in all cases respond to light.  However in box 3 the division is about 1:1.  This shows that the worms are attracted to the light but not like the situations where the dry area was next to the light.  When there is no choice between wet and dry such as in case IV the worms turn to the light.”

Note:  We might also test a box like this wet/dry with no light to further verify the effect of moisture.

Or create a matrix

	Wet	Dry	Totals
Most light	10 + 15 = 25	17 + 18 = 35	60
Less light	3 + 4 = 7	10 + 2 = 12	19
Totals	32	47

 

	Wet	Dry	Totals
Most light
Less light
No light
Totals

Could also add a third to moisture. Wet, moist, dry. (moist = 1/2 of what we is set to be.)