1Describe how to produce a scientific diagram
No sketched or hanging or crossing lines
No shading
No overlapping labels
It must look similar to the image and labelled correctly
Correct scale calculated and stated
2Describe how to measure an object using the eye piece gratitule in an optical microscope
Calibrate the gratitule using the stage micrometer
Count the number of divisions in the eye piece graticule to measure the image
Multiply the number of divisions by the calibrated measurement of each division
3Give the magnification equation
Magnification= size of image/size of real objesct
4Describe and explain how to prepare a specimen for a light microscope
Slice the specimen very thinly so light can pass through
Add a drop of stain to the specimen to increase contrast between different cellular components
Add the coverslip ensuring there are no air bubbles
5Give two safety precautions that must be taken when cutting a specimen
Cut onto a hard surface
Cut away from yourself
6Why do you press down lightly on the cover slip but not push it sideways
Push down
Do not push sideways as it may roll cells on top of one-another
7Describe the principles of a light microscope
Light microscopes use light transmitted through the specimen to form an image
They have a maximum resolution of 0.2μm meaning they are unable to show smaller cellular components such as ribosomes
The maximum magnification is about ×1500
8Give the difference between magnification and resolution
Magnification is how much bigger the image is compared to the object whereas resolution is the shortest distance between two points on a specimen that can still be distinguished as seperate by the observer
9Describe the principles of a TEM
Transmission electron microscopes (TEM) use a beam of electrons through the specimen to form an image
Electrons don't pass through as easily at denser parts
The image is therefore 2D
They have a high resolution of 0.1nm
The maximum magnification is about ×500,000
Samples need to be dead, thinly sliced and in a vacuum
The images are black and white
10Describe the principles of an SEM
Scanning electron microscopes use a beam of electrons to reflect off the specimen which are then scattered on to the receiver
The image is built by a computer to be 3D
They have a high resolution of 0.1nm
The maximum magnification is about ×100,000
The sample needs to be dead, thinly sliced and in z vacuum
The image is black and white
11Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of their use when studying cells
TEM uses electrons and optical use light; TEM allows a greater resolution; TEM can view smaller organelles and in greater detail
TEM view only dead specimens while optical microscopes can view live ones
TEM requires thinner specimens; requiring a more complex and time consuming preparation
TEM focuses using magnets and optical microscopes use glass lenses
12An electron microscope can see more detail and view smaller organelles than light microscopes
Electron microscopes have a much higher resolution than light microscopes so they can distinguish details that are much closer together