practical skills-mod 1

Question 1

millimetre to micrometre to nanometre

Answer 1

mm to pm= x 1000, pm to nm= x 1000
mm to nm=x 1 000 000
nm to pm= /1000
pm to mm=/1 000 000

Question 2

magnification equation

Answer 2

image size/actual size

Question 3

what is resolution

Answer 3

ability to distinguish two separate objects, minimum distance between two objects where they can still be seen as two objects

Question 4

unit conversions

Answer 4

1m= 1000 mm
1mm= 1000 pm
1pm= 1000nm

Question 5

light microscope

Answer 5

magnify to x1000
living and dead cells
stain may be needed
resolution capped to 200nm due nature of light
wavelength of light= 400nm to 700nm
details are seen at half of wavelength, blue is shortest
colour filters used for different resolutions

Question 6

how to prepare microscope slides

Answer 6

cut thin slice of specimen using tweezers
cut with scissors to size
clean coverslip with tissue
place peel on slide
add iodine or dye using pipette
squeeze flat lightly with mounted needle, non air bubbles

Question 7

graitcule v micrometer

Answer 7

measure specimen under microscope, graticule measured in epus whereas micrometer is 10mm in total length
large division=100pm/0.1mm
small division=100pm/0.01 mm
must be calibrated
1pm=0.001mm

Question 8

two types of mounts

Answer 8

wet mount-dip with liquid to allow variety of organisms,

dry mount-observe hairs and insect parts, thin slice so light can go through, tweezers pick up specimen

Question 9

biological drawing guidance

Answer 9

-draw what is seen not diagram, add annotations, use scale, label clearly, clear continous lines, no overlapping lines, no extreme detail, use accuracy, non arrowheads, use sharp pencil, detailed title, no ruler to draw cells, protractor to draw petri dish, add scale bar (measurement1/2)
high powering=detailed, individual cells, adjacent cells, no shading

low powering=different tissue and limit boundary lines, no single cells,

Question 10

what are the types of electron microscope

Answer 10

scanning/ SEM and transmitting/TEM

Question 11

how does the TEM microscope work

Answer 11

different areas of the specimen have different thicknesses and densities, different amount of electron pass through different regions, recorded on photographic plate

Question 12

how does a SEM work

Answer 12

electron bounces off specimen, detectors pick it up and dispplays image, direction of rebound gives information on surface topography and composition

Question 13

difference between SEM and TEM

Answer 13

transmission is 2d image, black and white, higher mag, lower res, ultrastructure

scanning is 3d image, black and white, lower mag, higher res, surface/topography

Question 14

what is a disadvantage of electron microscopes

Answer 14

cannot view living cells as they use vacuums

Question 15

effect of temperature on permability of membrane