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Scientific Method
Controlled Experiments
Independent vs. Dependent
Experimental Design
Bonus Questions
100
When heavy rains occur while apple or orchards are in bloom, the apple crop the following fall is much smaller than normal. This information can best be described as a/an
Observation
100
A drug company tested a new medication before putting it on the commercial market. Group A received pills containing the new medication while Group B received pills containing sugar. In this experiment, the individuals in Group B serve as the
Control Group
100
What is the name of the variable that is changed in the experiment?
independent variable
100
Cut flowers in vases of water do not last forever, but people have different ways to try to make them last longer. Three ideas that might help flowers last longer are putting a penny into the water, putting five drops of bleach into the water, and putting a packet of commercial "flower food" into the water. State a hypothesis that is consistent with the above information.
*Answers may vary* Example: Flowers that are given "flower food" will last the longest.
100
The pH of the water will affect of the heights of the radish plants. This statement is known as the ______ in a experiment
What is the hypothesis?
200
After looking outside and seeing the sidewalk is wet, your mother tells you it rained last night. This information is best described as...
An inference
200
A new drug for the treatment of asthma is tested on 100 people people. The people are evenly divided into two groups. One is given the drug, the other group is given a sugar pill. The experimental group is
Group given the experimental drug
200
What is the name of the variable that is being measured in an experiment?
Dependent Variable
200
Cut flowers in vases of water do not last forever, but people have different ways to try to make them last longer. The three we will consider here are putting a penny into the water, putting five drops of bleach into the water, and putting a packet of commercial "flower food" into the water. State the independent variable.
Treatment of cut flower (flower food, penny, or bleach)
200
An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. The heights of the radish plants were measured every 2 days for a period of 2 weeks. What is a possible hypothesis that was tested during the experiment?
"The pH of the water will affect the heights of the radish plants" Plants with a pH of ___ will grow more/less or faster/slower than _____
300
Tomato plants in a garden are not growing well. The gardener hypothesizes that the soil has the wrong pH. To test this hypothesis accurately, the gardener could...
Change the pH of the soil
300
Define controlled experiment.
What type of experiment contains one group receiving an independent variable and one does not? An experiment with only one difference between the groups
300
Where is the independent variable is placed on a graph?
The x-axis
300
Cut flowers in vases of water do not last forever, but people have different ways to try to make them last longer. The three we will consider here are putting a penny into the water, putting five drops of bleach into the water, and putting a packet of commercial "flower food" into the water. List 2 variables that should be controlled in this experiment.
type of flowers, type of water, type of vase, temperature of room, etc
300
An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. The heights of the radish plants were measured every 2 days for a period of 2 weeks. What was the dependent variable in this experiment?
The pH of the water. *This is the one thing that is different between groups at the START of the experiment.
400
The group being tested or receiving treatment is known as...
the experimental group
400
A student placed five geranium plants of equal size in five environmental chambers. Growing conditions were the same for each plant except color of light. At the end of 20 days, plant growth was measured. State one variable that should be controlled.
Answers May Vary -fertilizer -location of the plants (sunlight or shade) -temperature -intensity of light
400
Where is the dependent variable is placed on the graph?
On the the y axis
400
Cut flowers in vases of water do not last forever, but people have different ways to try to make them last longer. Three methods tested in one experiment were putting a penny into the water, putting five drops of bleach into the water, and putting a packet of commercial "flower food" into the water. State the dependent variable.
How fresh the flowers are; the appearance of the flowers
400
An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. The heights of the radish plants were measured every 2 days for a period of 2 weeks. What was the independent variable in this experiment?
The height of the plants. *This is the measurable outcome of the experiment.
500
Along with using controlled experiments, scientists also learn about the world through...
*Answers may vary* -Field Studies -Making Observations -Collecting data
500
Why is it important to test only one variable at a time?
To be certain your results are the result of that specific variable, not of some other difference between groups.
500
A scientist who was concerned about the effects of acid rain on newly fertilized fish eggs in lakes. She decided to investigate the hatching rates of these fish eggs in water at different acidic pH levels. Fish eggs were kept in water with different pH levels and the number of eggs that hatched was recorded. All other variables were controlled. ______ is the independent variable.
pH level because that it the single difference between groups at the start of the experiment.
500
When studying the effect of colored light on plant growth, Brian used two tomato plants in identical puts with the same soil. He watered each plant once a day with the same amount of water. He exposed one tomato plant to red light for 5 hours a day and the other to green light for 8 hours a day. Was his experiment a controlled experiment? Why or why not?
No-There were 2 differences between the groups. Color of light and hours of light.
500
An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. The heights of the radish plants were measured every 2 days for a period of 2 weeks . What is the testable question?
What is "Does the pH of the water will affect the heights of the radish plants"?