Homework Sourse1 brine shrimp or sea monkeys normally live at pH 8 you want
1. brine shrimp or sea monkeys normally live at pH 8. you want to test the effect of pH on the ability of brine shrimp to survive at a lower pH (pH 4,5 6 and 7).
a. what would be the experimental groups?
b. explain your answer.
c. what would be the appropriate control group?
d. explain your answer.
2. scientists have discovered a new drug to treat breast cancer. they determine the effectiveness of the drug by measuring the size of the patients tumor each week at two different doses ( low and high).
a. what is the control group in this experiment?
b. explain your answer.
c. what are the experimental groups in this experiment?
d. explain your answer.
Solution
1) The experimental groups would be shrimps growing at – pH 4, pH 5, pH 6 and pH 7 respectively.
Since the brine shrimps grow at pH 8, the control group will have the same pH.
Both control and experimental groups would be conducted in tank of equal size and volume, carrying equal amount of water at same temperature and aeration. Also the number of shrimps (also they should be of same growth phase or age and healthy) introduced to the tank would be same. pH 4 would have a significant declining effect on the brine shrimp population. With pH 5 and 6 it would have a climbing population curve, while pH 7 will have the highest population growth among the experimental groups as it is the closest to the natural living conditions of pH 8.
2) The control group in this case is one with placebo.
Control group is either given a standard treatment or a placebo. This placebo has no therapeutic effect and thus used as a control in testing for new drugs. Placebo (control) group ensures that it mimics the actual treatment.
The experimental groups are patients receiving low (n =48) and high dose (n=52) of the drug. The graph shows percentage change in the tumor size after the drug has been given in low and high dose.
