Experimental Design

Harvey A. Sweettooth, owner of the Sweettooth Candy Factory, has a fine line of hard candies. Recently, Mr. Sweettooth received a letter from a long time client, a Ms. Susie Saccharin, complaining that the candies in his assorted hard candies line did not all dissolve at the same rate.

1. Which of the following best represents the question that would lead to a scientific investigation of Ms. Saccharin's complaint?

1. Do all the candies last the same time?
   
2. Are all the candies the same size?
   
3. Do all the candies taste the same?
   
4. Do all the candies dissolve at the same rate?

2. Before an appropriate hypothesis can be formed, which information must be provided?

1. Whether all the candies taste the same
   
2. The surface area and volume of each type of candy
   
3. The mass of each type of candy
   
4. The color of each type of candy

3. Mr. Sweettooth suggests this hypothesis: "All candies dissolve at the same rate". Which of these would be the first step in preparing the experiment?

1. Gather all the types of candies
   
2. Call in people to serve as tasters
   
3. Contact Ms. Saccharin
   
4. Find out if there have been other complaints about the candies

A group of biology students has been reading about chicken eggs. Their research has lead them to form the following hypothesis: "The shell of a chicken egg is lined with a semipermeable membrane". A semipermeable membrane allows small molecules, like H₂O, O₂, and CO₂, to pass easily while keeping large molecules, like C₆H₁₂O₆ (glucose), from crossing.

The students used vinegar to remove the calcium shell from two eggs. They placed one egg in a beaker and covered it with water. They placed the second egg in another beaker and covered it with syrup.

4. If their hypothesis is correct, which of the following should be expected?

1. After 24 hours, both eggs will look the same
   
2. After 24 hours, one egg will be larger than the other
   
3. The eggs will float in their beakers
   
4. The eggs will hatch in their beakers

5. If their hypothesis is correct, which of the following should be expected?

1. Water will move into the egg covered with water
   
2. Water will move into the egg covered with syrup
   
3. Water will move out of the egg covered with water
   
4. Water will move into both eggs

An investigation was done to determine the relationship between color of light to which a Diffinia plant is exposed and the number of flowers it develops. A summary of the investigation is presented below.

Experiment 1: 10 Diffinia were grown under green lights at constant temperature with controlled amounts of moisture and food. The plants had, on average, two flowers each.

Experiment 2: 10 Diffinia were grown under normal sunlight at constant temperature with controlled amounts of moisture and food. The plants produced, on average, four flowers each.

Experiment 3: 10 Diffinia were grown under blue lights at constant temperature with controlled amounts of moisture and food. The plants produced, on average, six flowers each.

Experiment 4: 10 Diffinia were grown under red lights at constant temperature with controlled amounts of moisture and food. The plants did not produce flowers.

6. Which experiment served as the control?

1. experiment 1
   
2. experiment 2
   
3. experiment 3
   
4. experiment 4

7. Which of the following was a variable in this series of experiments?

1. temperature
   
2. color
   
3. food
   
4. plant species

8. Which is a valid conclusion based on experiment 3 alone?

1. blue lights make Diffinia produce more flowers than normal
   
2. blue lights make Diffinia produce fewer flowers than normal
   
3. Diffinia produce flowers if exposed to blue light
   
4. Diffinia produce flowers only if exposed to blue light