ExpertEasy1 markMultiple Choice
AQA GCSE · Question 04.3 · Cell Biology
Why was a thin layer of onion cells used?
Why was a thin layer of onion cells used?
Answer options:
A.
To allow light to pass through the cells
B.
To allow oxygen to pass through the cells
C.
To allow water to pass through the cells
How to approach this question
Consider how a light microscope works. What needs to travel from the light source, through the specimen, and into your eye for you to see an image?
Full Answer
A.To allow light to pass through the cells✓ Correct
To allow light to pass through the cells
A light microscope functions by shining a light from below, through the specimen on the slide, and then through the objective and eyepiece lenses to the observer's eye. For an image to be formed, light must be able to pass through the specimen. If the layer of cells is too thick, it will be opaque, blocking the light. Therefore, a very thin layer, ideally only a single cell thick, is prepared so that it is transparent enough for light to pass through and reveal the internal structures of the cells.
Common mistakes
✗ Focusing on other substances like oxygen or water, which are not relevant to the principle of light microscopy.
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