Chapter 2 - Basic components of living systems - microscopy

Question 1

what is the most common and earliest microscope called?

Answer 1

Light microscope

Question 2

give some advantages of a light microscope

Answer 2

cheap
easily available
can be used to observe living organisms

Question 3

name the lenses in a compound light microscope

Answer 3

objective lens (near the specimen) and eyepiece lens (the bit you look through)

Question 4

label a diagram of a light microscope

Answer 4

(top to bottom) 
eyepiece lens
coarse-focusing knob
fine-focusing knob
turret
objective lens
stage
light

Question 5

give the names and examples of the four types of slide preparation

Answer 5

dry mount (hair) wet mount (aquatic animals) smear slide (blood) squash slide (root tips)

Question 6

what are the key things to remember when drawing a biological diagram?

Answer 6

state the magnification
use as much of the available space as possible
draw smooth, not jagged lines
don’t shade
label lines shouldn’t cross or have arrow heads

Question 7

define magnification

Answer 7

how many times larger the image is than the actual size of the object

Question 8

define resolution

Answer 8

the ability to see individual objects as separate entities

Question 9

what is resolution limited by?

Answer 9

diffraction of light. in optical microscopy structures that are closer than half the wavelength of light cannot be resolved

Question 10

what can overcome limitations of resolution?

Answer 10

using laser beams - the wavelength is a thousand times shorter than light

Question 11

what is the magnification equation?

Answer 11

M=I/A

Magnification = size of Image/Actual size

Question 12

what is an eyepiece graticule?

Answer 12

a glass disc marked with a scale 1-100 with no units

Question 13

what is a stage micrometre?

Answer 13

a microscope slide with a scale marked in micrometres used to calibrate and measure size of specimens

Question 14

what is the limiting factor in light microscopy?

Answer 14

resolution

Question 15

give some disadvantages of electron microscopy

Answer 15

expensive
can only be used in a dedicated space
specimens can be damaged by the electron beam
the preparation process is very lengthy and complicated
there can be problems with artefacts

Question 16

what is an artefact?

Answer 16

structures produced during the preparation of the slide

Question 17

what are the two types of electron microscope?

Answer 17

SEM and TEM - scanning electron microscope and transmission electron microscope

Question 18

which type of electron microscopy has the best resolution?

Answer 18

TEM

Question 19

which type of electron microscopy produces a 3D image?

Answer 19

SEM

Question 20

what kind of microscope isn’t an electron microscope or a light microscope?

Answer 20

Laser Scanning Confocal Microscope

Question 21

how does a LSCMicrocsope work?

Answer 21

It moves a single spot of focused light across a specimen causing fluorescence from the components labelled with a dye. the emitted light is filtered through a pinhole aperture.