Question 1

In an experiment testing the effect of water on plant growth, which of the following is the independent variable?

Accepted Answer

The amount of water each plant receives

Question 2

A scientist wants to determine if a new fertilizer increases tomato yield. She applies the fertilizer to one group of plants and leaves another group untreated. What is the dependent variable in this experiment?

Accepted Answer

The yield (number of tomatoes produced)

Question 3

Which of the following best describes a positive control in an experiment?

Accepted Answer

A group that receives a treatment with a known response to ensure the experiment is working

Question 4

A student is testing which type of paper airplane design flies the farthest. What is the independent variable in this experiment?

Accepted Answer

The type of paper airplane design

Question 5

In an experiment, the temperature at which an alligator's egg is incubated determines the sex of the offspring. What is the dependent variable?

Accepted Answer

The sex of the baby alligator

Question 6

Which of the following best defines a variable in a scientific experiment?

Accepted Answer

A measurable or changeable element of the experiment

Question 7

A scientist is testing the effect of temperature on bacterial reproduction rate. Which is the independent variable?

Accepted Answer

The temperature at which the bacteria are incubated

Question 8

Why are negative controls important in experimental design?

Accepted Answer

They help identify effects not caused by the independent variable

Question 9

A researcher gives one group of patients a sugar pill and another group a new drug to test its effectiveness. The group receiving the sugar pill is an example of:

Accepted Answer

Negative control

Question 10

Which of the following statements about placebo controls is correct?

Accepted Answer

They help account for psychological effects in participants

Question 11

A scientist sets up four groups of wheat plants to study the effects of nitrogen: Group A gets 20 pounds/acre, Group B gets 40 pounds/acre, Group C gets 60 pounds/acre, and Group D gets 0 pounds/acre. Which group is the control group?

Accepted Answer

Group D

Question 12

Which of the following is an example of a false positive result?

Accepted Answer

A pregnancy test says you are pregnant when you are not

Question 13

In a controlled experiment, why is it important to only change one variable at a time?

Accepted Answer

To ensure that any observed effect is due to the variable being tested

Question 14

Which of the following best describes the role of a control group in an experiment?

Accepted Answer

It is used for comparison to see if the independent variable has an effect

Question 15

A scientist is testing a new medication. Patients in the experimental group fall asleep faster, while those in the placebo group do not. What does this suggest about the medication?

Accepted Answer

The medication is likely effective

Question 16

If a variable is kept constant throughout an experiment, what is it called?

Accepted Answer

Control variable

Question 17

Which of the following is an example of an independent variable in a real-world experiment?

Accepted Answer

The temperature at which bacteria are incubated

Question 18

A scientist wants to test the effect of light intensity on the rate of photosynthesis in plants. Which is the dependent variable?

Accepted Answer

The rate of photosynthesis

Question 19

Which of the following best describes a hypothesis in scientific research?

Accepted Answer

A testable prediction about the outcome of an experiment

Question 20

In an experiment, what is the main purpose of using both positive and negative controls?

Accepted Answer

To validate the experimental results by providing known outcomes

Experimental Design in Biology: Variables, Controls, and Practice

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