microscopes and magnification

Question 1

define the purpose of a microscope

Answer 1

observe tiny organisms that the human eye can not see

Question 2

define the function, magnification and structure of a light microscope

Answer 2

function -
uses visible light and lenses to magnify small objects
magnification -
up to x1000
structure -
-» eyepiece; the part you look in
-» objective lenses; places near the specimen
-» stage; the platform where the slide with the specimen is placed on
-» coarse and fine focus; used to focus on the image of the specimen
-» light source; provides light to make the specimen visible

Question 3

define the function, magnification and structure of a electron microscope

Answer 3

function -
uses beam of electrons instead of light to magnify objects
magnification -
up to x2,000,000 allowing higher resolution and magnification
structures -
transmission electron microscope ( TEM )
-» transmits electros through the specimen to create an image and is mostly used to examine thin sections of cells
scanning electron microscope ( SEM )
-» scans surface of specimen to create 3D image and is mostly used for surface details

Question 4

define magnification

Answer 4

how much larger an object appears to be compared to its actual size

Question 5

describe the formula for calculating magnification

Answer 5

. image size
magnification = —————
actual size

Question 6

define resolution

Answer 6

how clear and detailed an image is between two points that are very close together

Question 7

describe the formula for calculating actual size

Answer 7

. image size
actual size = ——————-
magnification

Question 8

describe the conversions from metre ( m ) to nanometre ( nm )

Answer 8

metre ( m ) - 1 metre
centimetre ( cm ) - 100 metres
millimetre ( mm ) - 1000 metres
micrometre ( um ) - 1,000,000 metres
nanometres ( nm ) - 1,000,000,000 metres
multiply by 1000 each time from one term to another

Question 9

list the rules to a biological cell drawing

Answer 9

-» use smooth lines
-» no shading
-» no colouring
-» only draw outlines of cell structure
-» label drawing with lines using pencil and ruler; no arrows
-» always add labels to the structure drawn

Question 10

describe the process to using a microscope

Answer 10

-» carry the microscope with one hand gasping the arm and the other holding the base
-» place the microscope on a flat surface and plug into a socket and switch on the light source
-» turn the nosepiece to the lowest objective lens until its clicked in at x10
-» place the slide on the stage and fasten it with the stage clips
-» raise the stage so the lens and slide is as close as possible without direct contact
-» use coarse focus to view the cells on the slide with clarity
-» use fine focus to make the view sharper
-» repeat the two steps above using a higher magnification lens
-» produce a biological drawing of the observed cell

Question 11

describe two reasons for the importance of microscopy

Answer 11

-» allow scientists to examine the structure of cells which allows us to understand the function
-» help diagnose diseases
-» used to study microorganisms, genetics and cell biology

Question 12

define the importance of iodine

Answer 12

some specimens are transparent so adding iodine or staining it adds contrast to the image making the cells visible