1What does magnification measure?
How much bigger the image is compared to the real object.
2What does resolution measure?
The ability to distinguish between two points or how detailed the image is.
3What is the formula for magnification?
Magnification = size of image / size of real object.
4What type of light do optical microscopes use?
They use visible light to form an image.
5What is the maximum resolution of an optical microscope?
About 0.2 micrometers (µm).
6What organelles can optical microscopes not see?
They can’t see ribosomes, the endoplasmic reticulum, or lysosomes.
7What is the maximum useful magnification of an optical microscope?
About ×1500.
8What do electron microscopes use to form an image?
They use a beam of electrons.
9What is the maximum resolution of an electron microscope?
About 0.0002 micrometers (µm).
10What is the maximum magnification of an electron microscope?
About ×1,500,000.
11What is an advantage of electron microscopes over optical microscopes?
They have a much higher resolution, so they can see smaller structures.
12What are the two types of electron microscopes?
Transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs).
13How do TEMs work?
They use electromagnets to focus a beam of electrons that passes through the specimen.
14What is an advantage of TEMs?
They give high-resolution images and show internal structures.
15What is a disadvantage of TEMs?
They can only be used on very thin specimens.
16How do SEMs work?
They scan a beam of electrons across the surface of the specimen.
17What kind of image do SEMs produce?
They create a detailed 3D image of the specimen's surface.
18What is an advantage of SEMs?
They show the surface of a specimen in detail.
19What is a disadvantage of SEMs?
They have a lower resolution than TEMs.
20What is the purpose of cell fractionation?
To separate organelles from a cell to study them.
21What are the three steps of cell fractionation?
Homogenisation, filtration, and ultracentrifugation.
22What happens during homogenisation?
Cells are broken apart using vibrations or grinding.
23Why is a buffer solution used in homogenisation?
To maintain pH and prevent damage to organelles.
24What happens during filtration?
The homogenised mixture is filtered to remove large debris or unbroken cells.
25What passes through the filter during filtration?
Organelles, as they are much smaller than the debris.
26What happens during ultracentrifugation?
The mixture is spun at high speeds to separate organelles by mass.
27Which organelles are separated first in ultracentrifugation?
The heaviest organelles, like nuclei.
28What organelles are separated after nuclei?
Mitochondria, then lysosomes, and finally lighter organelles like ribosomes.
29What is a key limitation of TEMs?
They can only be used on thin specimens.
30What is the main advantage of using SEMs for biological research?
They produce detailed 3D images of the specimen’s surface.
31Why is it important to keep the homogenised solution cold?
To reduce enzyme activity that could damage organelles.