But, Why SEX?
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McVeigh, Steve Dunbar VHS
1. To find the importance of sex in the study of continuity of life theme in
2. To show the idea of sex offering genetic variability therefore allowing evolution
to proceed at a faster rate when necessary.
Various sizes/colors of felt cloth - red, blue, yellow
Magnets (if chalk board is steel backed) and if NOT, then use pins, tacks, or
strips of Velcro tape
Colored dittos - red and blue will do
Ask students the description of the video Pacman game. Hopefully, they will
mention monsters, pacman, power pills, maze, etc. Then develop a "biological" pacman
maze by using a 3' by 3' piece of RED colored felt.
This felt becomes the background environment for the felt pacman shapes that can
stick to it.
Then describe the two pacman types. Each pactype has two traits: eye and skin
color. One pactype has red colored eyes and blue skin, the other has blue eye color
and red skin.
Arbitrarily decide that blue eye will have superior vision compared to red eye.
Superior referring to how they can see the power pills/monsters better than red eyes.
Have the students explain why red skin is superior to blue skin color. The idea is
that red skin is camouflaged by the RED (maze) environment.
Review, if necessary, the idea of genetic information being duplicated and the
products of this duplication are allocated approximately to the daughter cells so
that each receives only one copy of each message.
1. Have a yellow circle of felt as a nucleus placed within the pacman. Then have two
felt chromosomes of different shapes and colors to represent the two traits and
the alleles for that trait. Ask the students what would happen to the
chromosomes, if to reproduce, the pacman will undergo binary fission. Use smaller
felt pacmen for the daughter cells formed. Do this reproduction for both
2. Ask what traits would "Super Pacman" have, and what process would allow two
monoploid pactypes to produce an offspring with both beneficial characteristics,
i.e., superior vision and camouflage in the environment. Point out importance of
sexual reproduction in offering genetic variability.
3. Using colored ditto masters make an activity sheet that the student can mark in
the traits, chromosomes, and offspring pactypes, for both asexual & sexual
reproduction. However, this time have a BLUE maze environment, and let red eye be
superior to blue eye.
(Note: in any of the above activities, students can come to the felt maze and move
the pactypes and their offspring)
Article by A. Journet in Science Teacher, Oct' 84, page 50.