OCR- AS Biology- Unit 1, Module 1- Cells Questions

Question	Answer
What three things did Schwann and Schleiden say about cells?	-All living things consist of cells -New cells are formed from the division of old cells -Instructions for growth are passed on to new cells
What is the magnification and resolution of a light microscope?	x1500 magnification 200nm resolution
Which of TEM and SEM has a greater magnification?	TEM
What is the resolution of both TEM and SEM?	0.2nm
What is the definition of magnification?	Th number of times greater an image is than the object
What is the definition of resolution?	The ability to distinguish two separate points that are distinct from each other.
Why is a stain required in light microscopy?	This allows the different parts of a cell to become distinct from each other and creates definition.
What stain is used in TEM and what will the image look like?	Electrons pass through the sample- the more dense the sample, the longer it will take. False colour is applied afterwards to define between the different parts and this produces a 2D image
Why is a gold stain used in a SEM?	The gold stain allows the electrons fired at the sample to 'bounce' off, creating a 3D image that shows the contours of the specimen.
What is the equation for magnification?	Magnification= Image/ Actual

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	Created by Laura Perry about 9 years ago