Brine Shrimp Lab and Recessive Genes

 

In class, 10/3/13, we collected the second set of data for the brine shrimp lab. In this lab we placed different concentrations of salt water (0.0%, 0.5%, 1.0%, 1.5%, and 2.0%) into Petri dishes. Then we put around 20 brine shrimp eggs and covered them. We collected data after 24 hours and saw that the Petri dish that contained 1.5%   NaCl concentration had the highest number of shrimp swimming( 10 shrimps) , the second highest was the dish containing 0.5% NaCl concentration ( 6 shrimps), and the third was the 1.0% with 4 shrimp swimming. The other two containers did not have any shrimp swimming. After 48 hours we collected more data and saw that there were less shrimp swimming than before, 8 shrimps in the 0.5% and 1 in the 1.5%. The other three containers did not have any shrimp swimming. This lab shows that some shrimp developed variations which made them more adapted to higher concentration salt water than others, and the others could not survive it. This proves the theory of natural selection because only the shrimp that had these variations were more adapted (fit) to the changing environment survived and were able to pass on their genes.

 

 

 

 

            Also in class we did an activity about recessive genes.  We had two types of beads, red beads and green beads. We assigned the red beads to be the dominant gene. We place the beads into a paper bag and selected two beads at a time. If there was a pair of green beads they would die off because it was not the dominant gene. We repeated this process several times and each time we excluded the pairs of not dominant beads. Eventually we found that the dominant gene, the red beads, became more prevalent. This activity represents an isolated community and how the genes over time become similar and recessive.