Experiment #1
Question: Does penicillin prevent infection?
Hypothesis: If the medicine prevents infection, than the medicine will prevent the growth of bacteria that cause infection.
Experiment: Leo placed two circles of paper in a 500 Petri dish (something used for growing bacteria).In 250 dishes, the paper was soaked with Peniccilin solution and then inoculated with bacteria. The other 250 dishes were soaked in water only and inoculated with same bacteria .All other conditions including light and temperature remained the same. After 48 hours, Leo observed all dishes and noticed there was no bacteria growth in the penicillin dishes a circle. All dishes with water only had large colonies of bacteria growing in them.
At the end of the experiment, a circle with a radius of 2cm formed around the circle of paper soaked in penicillin. There were no bacteria growing in the 2cm circle. No change had occurred around the other circle of paper. The bacteria were growing well.
A. What was the independent variable? ______________________________________________________
B. What was the dependent variable? ________________________________________________________
C. What was the control? _____________
D. What was the constant
E. What type of study is this? Explain
Experiment 2: Does eating a new sauce of Krabby Patties reduce the incident of gas?
Mr. Krabbs wants to make Bikini Bottom a nicer place to live. He has created a new sauce he thinks will reduce the production of body gas associated with eating krabby patties from the Krusty Krab. He recruits 100 customers with a history of gas problem. He has 50 of them (Group A) eat krabby patties with the new sauce. The other 50 (Group B) eat krabby patties with sauce that looks just like the new sauce, but is really just a mixture of mayonnaise and food coloring. Both groups were told that they were getting the sauce that would reduce gas production. Two hours after eating the krabby patties, 30 customers in group A reported having fewer gas problems and 5 customers in group B reported having fewer gas problems.
A. What was the independent variable? The sauce used in Group A
B. What was the dependent variable? The amount of body gas
C. What was the control? Group B
D. What was the constant
The time.
E. What type of study is this? Explain
Placebo Effect The new Krabby pattie sauce is effective towards the hypothesis and reduces gas production this is evident as 30 customers in group A reported having fewer gas problems. 5 customers in group B also had fewer gas problem.
Is Rubella virus associated with higher levels of birth defect?
Mothers who contract rubella during lattrer part of pregnancies have babies with higher rates of cardiac, visio and hearing disoders.
To test their observation, Dr Kulkarni studies more than 1200 pregnant women in 4 hospitals over a period of 7 years. Of the 1200, they tracked the mothers health during the final trimester,a nd infant health during the first year after birth. When a mother shows visible sympotoms of rubella, Dr Kulkarnis team noted the severity and duration of her symptoms. From their data, the observed that women who showed symptoms of rubella were 200 times more likely than women with no symptoms to give birth to a baby with heart problems, blindness and deafness.
A. What was the independent variable?
B. What was the dependent variable?
C. What was the control?
D. What was the constant
E. What type of study is this? Explain