IB Biology Skills: Validity 1

The video tutorial covers the concept of validity in IB Biology experiments, focusing on the roles of independent, dependent, and controlled variables. It uses examples from an archery competition and a catalase activity experiment to illustrate how these variables affect the validity of conclusions. The tutorial emphasizes the importance of changing only one independent variable at a time to ensure valid results and discusses how to select appropriate dependent variables. It also highlights the need to maintain controlled variables to draw meaningful conclusions.

What is the primary aim of a science experiment?

• To change as many variables as possible

• To see how changing the independent variable affects the dependent variable

• To keep all variables constant

• To measure the speed of the reaction

In the archery competition example, what was the independent variable?

• The distance to the target

• The type of bow used

• The archer

• The weather conditions

Why is it important to have only one independent variable in an experiment?

• To make the experiment more complex

• To attribute changes in the dependent variable to a single cause

• To ensure the experiment is quick

• To allow for multiple conclusions

Which of the following is a valid dependent variable in the catalase experiment?

• The temperature of the solution

• The color change of the solution

• The height of the column of oxygen bubbles

• The time it takes for bubbles to reach the top

What is a controlled variable?

• A factor that is kept constant in an experiment

• A factor that is measured in an experiment

• A factor that is ignored in an experiment

• A factor that is changed in an experiment

Why must controlled variables be kept constant?

• To ensure the experiment is easy to perform

• To prevent them from affecting the dependent variable

• To make the experiment more interesting

• To allow for multiple independent variables

In the archery competition, why is it important that all archers use the same type of bow?

• To allow for different styles

• To make the competition more challenging

• To test different types of bows

• To ensure the competition is fair

What is the role of the independent variable in an experiment?

• It is the factor that is measured

• It is the factor that is kept constant

• It is the factor that is ignored

• It is the factor that is manipulated or changed

What should be the focus when selecting a dependent variable?

• It should be the most complex factor

• It should directly address the experimental aim

• It should be easy to measure

• It should be unrelated to the independent variable

What is the key takeaway regarding validity in experiments?

• Validity ensures that the experiment tests the aim and hypothesis

• Validity is only about measuring the dependent variable

• Validity is about changing as many variables as possible

• Validity is not important in experiments