High School Biology-Chemistry SMILE Meeting
27 February 2001
Notes Prepared by Porter Johnson

Ben Stark (IIT Biology) Mendel's First Law
He asked about the inheritance pattern of the offspring with respect to red and yellow corn. He described the following experiment that he had done previously:

  1. Take pollen from red and yellow corn, and place on corn silks of opposite type.
  2. Wait for the seeds to develop on cobs, and see the results. All are red.
  3. The first generation is then crossed, and their offspring examined at full development. Some are red and some are yellow, but not in the same proportion.
  4. R gene (alleles)  Þ color (R: red or r: yellow) of kernel.
We conclude that R (red) is dominant over r (yellow). For every gene there are two copies per cell, so you can have RR (red), Rr (red), and rr (yellow).

Gametes have only one gene, but body cells have two  For gametes we have the following rules:

We represent the possibilities through the Punnett Square for the first cross:  RR ´  rr:

First\Second

r r
R  Rr (red) Rr (red)
R  Rr (red) Rr (red)

Now the Punnett Square for the second cross:  Rr ´ Rr:

First\Second

R r
R  RR (red) Rr (red)
r  rR (red) rr (yellow)

Thus, we expect the second generation to by 75 % red and 25 % yellow.  Actual results with 150 seeds:

112 red 74.66 %
38 yellow 25.33 %

Pat Riley (Lincoln Park HS) Gas Laws
Non-Mathematical Part:

Part involving some mathematics:
Pressure
(Number of Books)
Volume (cm3) Inverse Volume (cm-3)
0 100 10.0 ´ 10-3
1 97 10.3 ´ 10-3
2 83 10.8 ´ 10-3
3 86 11.6 ´ 10-3
4 75 13.3 ´ 10-3
5 70 14.3 ´ 10-3

More mathematical part:


          6  |
  Pressure   |                                  *
  # books    |                                *
          3  |                              *
             |                            *
             |                          * 
             |________________________*_________
             |    2    4    6    8   10   12   14   10-3
             |                    .
             |    1/V           .
          -3 |                .
             |              . 
             |            . 
          -6 |          .
             |        .
             |      .
          -9 |    .
             |  .
             |.
         -12 |

Atmospheric pressure [as measured in "number of books" on syringe] corresponds to the crossing point on the vertical axis; the vertical intercept,  or about 11 or 12 books.

Next presentation: Charles Law

Notes taken by Therese Donatello.