Microscopes

Question 1

Light Microscopes

Answer 1

• can achieve a magnification of 2,000 times max of x400 or x1000 common in labs
• resolution is 0.2 UM the higher the magnification of the image = more detail you see
• magnification to see distance smaller than 0.2 UM does no give more detail
• possible to see nucleus and nucleolus in a typical animal cell

Question 2

Electron Microscope

Answer 2

• simplest way to magnify is using hand lens
• 10 to 20 fold magnification
• two or more lenses used together = greater magnification
• greater resolution than light microscopes because electrons have a much shorter wavelength than visible light
• can resolve 0.1 NM apart

Question 3

Magnification

Answer 3

Number of times an image is bigger then the object from which it is derived

Question 4

Resolution

Answer 4

Smallest distance that can be distinguished as two separate point in a microscope
• tells you how close two point can be and still be separately distinguished

Question 5

Onion Epidermis

Answer 5

1) cut a white onion vertically and remove leaf
2) insert fine forceps just below the epidermis on adaxil surface, which is upper surface on a piece of onion curving upwards
3) maintain tension on the sheet of cells that lifts off, cut it off with scissors
4) use scissors to cut a square of unfolded epidermis, each slide 5mm
5) two drops of methylene blue or iodine and cover with a slab

Question 6

Red Onion & Rhubarb Epidermis

Answer 6

1) insert fine forceps just beneath the epidermis of a rhubarb petiole or adaxial epidermis of a red onion leaf
2) place over slide, use scissors to cut a square of unfolded epidermis, each slide 5mm
3) two drops of water on the specimen and cover

Question 7

Amoeba

Answer 7

1) pipette two drops of liquids Amoeba, place in a slide
2) add two drops of glycerol, increasing viscosity to slow Amoeba’s movements

Question 8

Eyepiece Graticule (epu)

Answer 8

• in eye piece to calculate size
• objective lenses of different magnification = divisions on graticule represents different lengths
• higher power of objective lens = smaller length each division of graticule represents

Question 9

Stage Micrometer (smu)

Answer 9

• microscope slide on which the object is a line 1MM
• ruled with markings for tenths and hundredths of MM

Question 10

Calibrating a Microscope

Answer 10

1) line zero of eyepiece graticule with a major division of stage micrometer - gradual lines are parallel
2) look along line to where they coincide again
3) calculate with x40 objective lens
4) 80 epu = 20 smu
5) 1 epu = 20 divided by 80 smu x 0.01 MM
= 0.0025 MM
1 epu = 0.0025 x 1000 UM
= 2.5 UM

Question 11

Making a Measurement

Answer 11

1) middle of vision
2) rotate eyepiece to be parallel along measure line
3) count number of small epu to make measurements
4) using x40 maximum length = 99 epu
x40 means 1 epu = 2.5 UM
99 x 2.5 = 247.5 UM

Question 12

Magnification of Drawing

Answer 12

• magnification = image size divide by actual size
Measure in mm not cm (1 cm = 10 MM)
1) converts to UM 1 MM : 1000 UM
2) make sure everything is the same unit
3) image larger than object = magnification is greater than 1 (vice versa)

Question 13

Measure from Electron Micrographs

Answer 13

Object size = image size divided by magnification