Practice - Compose a coherent, structured lab report adhering to IB MYP Objectives A–C, integrating scientific terminology with reflective commentary.
Practice Questions
Test your understanding with targeted questions
In the context of the microscopy chapter, what is the independent variable when you are specifically testing the effect of different stains on a cell sample?
* Answer: The type of stain (or stain brand/chemical).
* Hint: It's the factor you intentionally choose to manipulate or change.
💡 Hint: It's the factor you intentionally choose to manipulate or change.
Name a cellular structure (e.g., in an onion cell) that is the dependent variable you are observing for clarity.
* Answer: The nucleus (or cell wall, cytoplasm, or specific organelles).
* Hint: It's the part of the cell whose visibility changes based on the stain.
💡 Hint: It's the part of the cell whose visibility changes based on the stain.
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Interactive Quizzes
Quick quizzes to reinforce your learning
When comparing the effectiveness of two different stains, the dependent variable is:
* Type: mcq
* Options: The stain used, The light intensity, The resulting clarity of the cell structure
* Correct Answer: The resulting clarity of the cell structure
* Explanation: The clarity is the factor that is measured or observed as the result of changing the independent variable (the stain).
* Hint: What outcome are you measuring?
💡 Hint: What outcome are you *measuring*?
True or False: In a controlled microscopy experiment, the independent variable is the factor that must be kept the same across all trials.
* Type: boolean
* Options: True, False
* Correct Answer: False
* Explanation: The controlled variables are kept the same; the independent variable is the factor that is deliberately changed.
* Hint: What do you manipulate in the experiment?
💡 Hint: What do you *manipulate* in the experiment?
2 more questions available
Challenge Problems
Push your limits with advanced challenges
Design a basic procedure to test whether the age of a slide (freshly prepared vs. 24 hours old) affects the visible structure of a stained cell. Clearly identify all three variable types.
* Solution:
* Procedure: Prepare two identical slides (e.g., cheek cells). Stain both slides using the same stain concentration, light intensity, and microscope setting. Observe and record the clarity of structures on the first slide immediately. Observe the second slide 24 hours later using the exact same settings and record the clarity.
* Independent Variable: Age of the slide (time elapsed).
* Dependent Variable: Clarity/intactness of cell structures.
* Controlled Variables: Stain type and concentration, light intensity, sample type, microscope setting/magnification.
* Hint: The only factor you are varying is the time, everything else must be fixed.
💡 Hint: The only factor you are varying is the time, everything else must be fixed.
Evaluate the statement: "In a microscopy comparison of stain concentration, it is acceptable for the observer to adjust the light intensity to make each sample look as clear as possible."
* Solution: The statement is false. Adjusting the light intensity (a controlled variable) for each sample introduces an uncontrolled factor. Changes in perceived clarity could be due to the altered light intensity rather than the stain concentration, invalidating the experiment's conclusion. To ensure a valid comparison, the light intensity must be kept constant for all observations.
* Hint: If you change the light, how can you be sure the stain is the only factor affecting visibility?
💡 Hint: If you change the light, how can you be sure the stain is the only factor affecting visibility?
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