The compound light microscope effectively

26 Jun The compound light microscope effectively

Question
MicroscopyandtheMetric System

MargaretE.Vorndam,M.S. Version42-0090-00-01

Lab Report Assistant

Thisdocumentisnotmeanttobeasubstitute foraformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables that shouldbeaddressedinaformallabreport. Theintentistofacilitatestudents’writing oflab reports by providing this informationin an editable filewhich can be sent to an instructor.

Observations

DataTable1:CalculatingMagnification

Ocular Lens Magnification

x

ObjectiveLenses

Magnification=

Total Magnification

Data Table 2: Diameter of a Viewing Field

Magnification

(ocular x objective

lens’powers)

mm diameter

of fieldof view

μm diameter *

of fieldof view

Scanning Lens

LowPowerLens

HighPowerLens

Exercise1:Measuring Length,Weight,Volume, and

Temperature

Try the following conversions for practice.

240,000 ng = mg = g 50 cm = mm= m

Procedure

1. Length:Ametricrulerisusefulformeasuring itemsoflength.Therulerbelowmeasuresin mm, indicated by the small mm near 0.

a. How many mm are there in 1 cm? , in a meter (m)?

.0/msohtmlclip1/01/clip_image002.jpg”>

(Ruler is not to scale. See ruler in dissectionkit.)

b. Locateameasurableobjecttouseforthisexercise.Iftheobjectislong,obtaina yardstick that includes a cm scale; they can be found in local hardware stores.

c. Record the length of the object below and do the conversions:

Name of object

Volume:Alwayspouranapproximatevolumeofliquidintoacleanbeakerandthenfromthe beakerintothevolumetricflask orgraduatedcylinder.Thiswillminimizecontaminationofthe parentliquidsource.Dispose properlyofanyleftoverliquid. DoNOTpouritbackintotheoriginal container. Why?

Whenusingapipetordroppertomeasure liquid,pouranaliquotintoacleanbeaker andthen drawuptheliquidfromthebeakerintothepipet.NEVERtrytodraw upchemicalsbymouth. Why?

Weight:Usethepenscalefromthelabkittomeasureoutexactlythreegramsofsugar.Make suretotarethebagbeforeaddingthesugar.Whymustthebagbetaredbeforeaddingthesugar?

How is the weight of the bag accounted for when the sugar is weighed?

Temperature:

Practiceconvertingthe following with this conversion formula:

45°F = °C 62°F = °C 98.6°F = °C

45°F = 62°F = 98.6°F =

UseaCelsius thermometertomeasurethe°Ctemperatureofseveraldifferent aliquotsofcold andwarmtapwater.Makesuretoallowthethermometertoremainuntil thetemperatureis stable and no longer changes.Record the temperatures:

°C

°C °C

Questions

A. What laboratory equipment would be used to measure the following items?

5 g flour

36 mL water

The length of a frog’s leg

36 g water

38ºC

Volume of a turtle*

125ºF

Volume of blood

Weight of a plant

Weight of blood

Temperature of a fish’sbody

Temperature of blood

*This answer may require some creativity.How could it be done?

B. Providethecalculationsteps,including theconversionfactorthatwouldbeneededtoconvert the followingmeasurements, andthefinalanswers.UseU.S.andliquid unitswhereappropriate.

248 g

= mg

145,000 μL

= mL

536 mL

= cc

0.372 kg

= g

0.75 L

= μL

20.39 cm

= m

C. Providethecalculationsteps,including theconversionfactorthatwouldbeneededtoconvert the following measurements, and the finalanswers. Use US and liquid units where appropriate.

3 cups = L 7,893 mg = lb

2.25 oz = cc 36ºC = ºF

145,000 uL = tsp 96ºF = ºC

D. WhatadvantagesdoesthemetricsystemhaveovertheEnglish methodofmeasurement? What are the disadvantages?

E.Outline the steps necessary to accurately weigh 3.5 g of starch.

F. Outlinethestepsnecessarytoaccuratelypipet5mLofdistilled water.Pouranaliquot of distilledwater into a clean beaker.

Exercise 2: Microscopy

Thecompound lightmicroscopeeffectivelymagnifies intherangeof40xto2000x.Ifanobject under view is 10 nm in length without any magnification, what will be its viewing size at 40x?

at 2000x?

What is the equivalent size at these magnifications,in inches? Show your calculations.

Thescanning electronmicroscope (SEM)employselectronbombardmenttoimageverysmall specimens.Electronmicroscopesare used toimage specimensthat range from 1 nmto100 µm in size. What is the equivalent in inches? . Show your calculations.

Procedure

1. PartsoftheCompound LightMicroscope:Refertoamicroscopeasthissectionis read.Label the microscope diagram that follows as the examinationof the microscope proceeds.

a. Eyepiece(OcularLens):Themagnification powerisstampedontheoutsideofthelens.

Whatisthepoweroftheocularlens?Microscopesmayhaveinterchangeableocular

lenses of differentmagnification.

b. Body Tube:Holds the ocular and objectivelenses at the correct focal distance.

c. Arm:Used to transport microscope and hold the body tube.

d. Nosepiece:Therevolvingdevicethatholdstheobjectivelenses.Mayalsobereferredto as the turret.

e. ObjectiveLenses:Consists of one or more lenses:

i. The scanning power objectivelens is the shortest of the lenses. What is its power?

ii. The low-power objectiveis slightly longer than the scanning objective.What is its power?

iii. The high-power objectiveis longer than the low-power objective.What is its power?

Label this microscope diagram with the appropriate part names and their functions:

.0/msohtmlclip1/01/clip_image004.gif”>a b c

d e f g h i

Parts not included in microscope are:

2. Focusing the Microscope:

If the microscope includes an oil immersion lens, place a drop of immersion oil on the slide cover slip before rotatingthe lens into place. The functionof the oil is to minimize light diffractionthrough the slide and subject so that greater detail can be seen. Afterusing the oil immersion lens, clean excess oil offof the lens and the slide with a lens cloth. Never tilta microscope when using oil or if viewing a wet slide. Why?

3. Operatingthe Microscope:

a. Obtainacleanslideandcover slipfromthe slidebox.Place the slideandcover slip separatelyonapapertowelorothersoft surfacetoreducethepossibilityofscratching them.

b. With scissors, cut a letter “e” from an old magazine or newspaper. c. Place the letterin the center of the slide.

d. Follow the instructionsin Section6 below to make a wet mount of the letter.

e. Followingthedirections outlinedaboveunderHandling andFocusing theMicroscope, place the prepared slide on the microscope stage. Leave the scanning lens in place and focussothattheletterisclearly viewable.Makedrawingsoftheletterintheboxesbelow as instructed.

Sideof the slidefurthestawayfrom student

Look from the side of the microscope, view

and then draw the letterhere, as it appears on

the slide on the stage.

Draw the letterhere as it appears when viewing it through the microscope.

Sideof the slideclosesttostudent

f. Whatisobserved?Microscopesinverttheimageontheslide.Thismeansthatthesubject will appear to be 180° rotated and reversed from the actual image viewed on the slide.

g. While viewingtheletterthroughthelenses,movetheslideslightly.Whatdoyouobserve about the movement of the letterand slide when viewed through the lenses?

h. Use thedirectionsabovetoviewtheletteratthehigherobjectivepowers.Onthedrawing made above,circletheportion oftheletterthatisviewableassuccessivelyhigherpower observationsaremade.Whatis yourconclusionaboutwhathappenswhenhigherpower objectivesare used?

4. TotalMagnificationCalculation:Typically,theocularlensofamicroscopewillbe10x,butit may be higher or lower. The power is recorded on the side of the lens.

a. Whatistheocularlenspowerofthemicroscopethatyouareusing?Itmaybe10xor15x.

Record it in Table 1.

b. The objectivelenses alsohavethemagnificationpowerrecordedontheirsides. What powers do the objectivelenses on the microscope have? Record them in Table 1.

c. Now,calculatethetotalmagnificationoftheviewingareabymultiplyingthepowerof the ocularlenswiththatoftheobjectivelensinuse.Forinstance, ifamicroscopehas a10xmagnificationocular lensanda4xobjectivelensinplaceforviewing,thetotal magnificationwillbe40x(10xmultiplied by4x).Whatotherviewmagnifications are possiblewiththemicroscope?Calculatethetotalmagnificationforeachsetoflensesin Table 1.

Table 1: CalculatingMagnification

Ocular Lens Magnificationx

ObjectiveLenses

Magnification=

Total Magnification

5. Diameter of Field:

a. Withthelow-powerobjective inviewingposition, placeashorttransparentmetricruler on the stage.

b. While viewingtherulerthroughthelenses,measurethelow-powerdiameteroffieldof view in mm. Convert this measurement to μm and record in Table 2.

c. Switchtotheother higherpowerobjectives,noting thediameter,inmm,foreachinTable

2.Convertmeasurementstoμm.Howmightthisinformationbeusefulwhenviewing

microscopic subjects?

Table 2: Diameter of a Viewing Field

Magnification

(ocular x objectivelens’

powers)

mm diameter

of fieldof view

μm diameter *

of fieldof view

Scanning Lens

LowPowerLens

High PowerLens

6. DepthofField: Prepareawetmountslideofthreedifferentlycoloredcrossedthreadsusing the wet-mount techniquedescribed above. Place the slideon the microscope stage with the threadcrossingareainthecenter oftheviewingarea.Focuscarefully,movingthescanning objectivelens up and down, taking care not to break the cover slip.

Record the order of the threads in this table. Note that, when one thread is in focus, the others appear blurred. Why? When you focus on another thread, what happens to the thread that you were viewing?

Depth

ThreadColor

Top

Middle

Bottom

Switch to high power and focus on one thread, then focus on another thread. What do you noticeabout the depth of field?Can you see as much of the thread in focus at the high power as you could at the low power magnification?

7. View an animal cell:

a. Observe the prepared slideunderthe microscope, beginningwiththe scanninglensand then proceedingtohighermagnificationlevels.Locatethenucleus inseveralcells.Locate the cytoplasmandthe plasmamembrane. Ona sheet ofpaper, make a drawingofa few cells, and label the observed parts.

8. View a plant cell:

a. Observe the slide under the microscope, beginning with the scanning lens and then proceeding to higher magnification levels. Locate the cell wall and the nucleusinseveralcells.Makeadrawingofafewcellsandlabeltheobservedparts.

b. Countacolumnofcells,stackedend-to-end,acrossthefield ofvisionunderhigh-power magnification.

c. F. Basedonthefieldofvisionmeasurementyoucalculatedabove,computetheaverage length of one cell in the column of cells with this formula:

μm average length of cell = μm diameter of fieldof view ÷ total number of cells in the column.

d. What differenceswere noted between the animal cells and the plant cells?

e. How do the differencesdictate the form of the organism?

Discussion

A. What is the purpose of staining cells before viewing them under a microscope?

B. Whattypeofmicroscopewouldyouusetoviewthefollowingorganisms? Theremaybemore than one correct response for each.

Strep throat culture

Mitochondria in an animal cell

Structure of a bird feather

Chloroplasts in a leaf cell

Earthworm digestive system

Enterococcusbacteria

DNA structure in the nucleus

Spores from a mushroom

Cells from plant leaf

Herpes simplex

C. Summarize the capabilitiesof each of the microscopes listed in Table 2-3 below.

Table 3: Summary of Microscope Capabilities

Typeof Microscope

TypeofDetection

Beam

MagnificationRange,metric

Examples of ViewableSpecimens

Dissecting

CompoundLight

Scanning electron

Transmission electron

Laboratory Summary

1. What have you learned from doing this laboratory?

2. Why is the informationpresented in this laboratory intrinsic to all future studies in biology?

Lab Report Assistant

Thisdocumentisnotmeanttobeasubstitute foraformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables that shouldbeaddressedinaformallabreport. Theintentistofacilitatestudents’writing oflab reports by providing this informationin an editable filewhich can be sent to an instructor.

Observations

DataTable1:CalculatingMagnification

Ocular Lens Magnification

x

ObjectiveLenses

Magnification=

Total Magnification

Data Table 2: Diameter of a Viewing Field

Magnification

(ocular x objective

lens’powers)

mm diameter

of fieldof view

μm diameter *

of fieldof view

Scanning Lens

LowPowerLens

HighPowerLens

Exercise1:Measuring Length,Weight,Volume, and

Temperature

Try the following conversions for practice.

240,000 ng = mg = g 50 cm = mm= m

Procedure

1. Length:Ametricrulerisusefulformeasuring itemsoflength.Therulerbelowmeasuresin mm, indicated by the small mm near 0.

a. How many mm are there in 1 cm? , in a meter (m)?

.0/msohtmlclip1/01/clip_image002.jpg”>

(Ruler is not to scale. See ruler in dissectionkit.)

b. Locateameasurableobjecttouseforthisexercise.Iftheobjectislong,obtaina yardstick that includes a cm scale; they can be found in local hardware stores.

c. Record the length of the object below and do the conversions:

Name of object

Volume:Alwayspouranapproximatevolumeofliquidintoacleanbeakerandthenfromthe beakerintothevolumetricflask orgraduatedcylinder.Thiswillminimizecontaminationofthe parentliquidsource.Dispose properlyofanyleftoverliquid. DoNOTpouritbackintotheoriginal container. Why?

Whenusingapipetordroppertomeasure liquid,pouranaliquotintoacleanbeaker andthen drawuptheliquidfromthebeakerintothepipet.NEVERtrytodraw upchemicalsbymouth. Why?

Weight:Usethepenscalefromthelabkittomeasureoutexactlythreegramsofsugar.Make suretotarethebagbeforeaddingthesugar.Whymustthebagbetaredbeforeaddingthesugar?

How is the weight of the bag accounted for when the sugar is weighed?

Temperature:

Practiceconvertingthe following with this conversion formula:

45°F = °C 62°F = °C 98.6°F = °C

45°F = 62°F = 98.6°F =

UseaCelsius thermometertomeasurethe°Ctemperatureofseveraldifferent aliquotsofcold andwarmtapwater.Makesuretoallowthethermometertoremainuntil thetemperatureis stable and no longer changes.Record the temperatures:

°C

°C °C

Questions

A. What laboratory equipment would be used to measure the following items?

5 g flour

36 mL water

The length of a frog’s leg

36 g water

38ºC

Volume of a turtle*

125ºF

Volume of blood

Weight of a plant

Weight of blood

Temperature of a fish’sbody

Temperature of blood

*This answer may require some creativity.How could it be done?

B. Providethecalculationsteps,including theconversionfactorthatwouldbeneededtoconvert the followingmeasurements, andthefinalanswers.UseU.S.andliquid unitswhereappropriate.

248 g

= mg

145,000 μL

= mL

536 mL

= cc

0.372 kg

= g

0.75 L

= μL

20.39 cm

= m

C. Providethecalculationsteps,including theconversionfactorthatwouldbeneededtoconvert the following measurements, and the finalanswers. Use US and liquid units where appropriate.

3 cups = L 7,893 mg = lb

2.25 oz = cc 36ºC = ºF

145,000 uL = tsp 96ºF = ºC

D. WhatadvantagesdoesthemetricsystemhaveovertheEnglish methodofmeasurement? What are the disadvantages?

E.Outline the steps necessary to accurately weigh 3.5 g of starch.

F. Outlinethestepsnecessarytoaccuratelypipet5mLofdistilled water.Pouranaliquot of distilledwater into a clean beaker.

Exercise 2: Microscopy

Thecompound lightmicroscopeeffectivelymagnifies intherangeof40xto2000x.Ifanobject under view is 10 nm in length without any magnification, what will be its viewing size at 40x?

at 2000x?

What is the equivalent size at these magnifications,in inches? Show your calculations.

Thescanning electronmicroscope (SEM)employselectronbombardmenttoimageverysmall specimens.Electronmicroscopesare used toimage specimensthat range from 1 nmto100 µm in size. What is the equivalent in inches? . Show your calculations.

Procedure

1. PartsoftheCompound LightMicroscope:Refertoamicroscopeasthissectionis read.Label the microscope diagram that follows as the examinationof the microscope proceeds.

a. Eyepiece(OcularLens):Themagnification powerisstampedontheoutsideofthelens.

Whatisthepoweroftheocularlens?Microscopesmayhaveinterchangeableocular

lenses of differentmagnification.

b. Body Tube:Holds the ocular and objectivelenses at the correct focal distance.

c. Arm:Used to transport microscope and hold the body tube.

d. Nosepiece:Therevolvingdevicethatholdstheobjectivelenses.Mayalsobereferredto as the turret.

e. ObjectiveLenses:Consists of one or more lenses:

i. The scanning power objectivelens is the shortest of the lenses. What is its power?

ii. The low-power objectiveis slightly longer than the scanning objective.What is its power?

iii. The high-power objectiveis longer than the low-power objective.What is its power?

Label this microscope diagram with the appropriate part names and their functions:

.0/msohtmlclip1/01/clip_image004.gif”>a b c

d e f g h i

Parts not included in microscope are:

2. Focusing the Microscope:

If the microscope includes an oil immersion lens, place a drop of immersion oil on the slide cover slip before rotatingthe lens into place. The functionof the oil is to minimize light diffractionthrough the slide and subject so that greater detail can be seen. Afterusing the oil immersion lens, clean excess oil offof the lens and the slide with a lens cloth. Never tilta microscope when using oil or if viewing a wet slide. Why?

3. Operatingthe Microscope:

a. Obtainacleanslideandcover slipfromthe slidebox.Place the slideandcover slip separatelyonapapertowelorothersoft surfacetoreducethepossibilityofscratching them.

b. With scissors, cut a letter “e” from an old magazine or newspaper. c. Place the letterin the center of the slide.

d. Follow the instructionsin Section6 below to make a wet mount of the letter.

e. Followingthedirections outlinedaboveunderHandling andFocusing theMicroscope, place the prepared slide on the microscope stage. Leave the scanning lens in place and focussothattheletterisclearly viewable.Makedrawingsoftheletterintheboxesbelow as instructed.

Sideof the slidefurthestawayfrom student

Look from the side of the microscope, view

and then draw the letterhere, as it appears on

the slide on the stage.

Draw the letterhere as it appears when viewing it through the microscope.

Sideof the slideclosesttostudent

f. Whatisobserved?Microscopesinverttheimageontheslide.Thismeansthatthesubject will appear to be 180° rotated and reversed from the actual image viewed on the slide.

g. While viewingtheletterthroughthelenses,movetheslideslightly.Whatdoyouobserve about the movement of the letterand slide when viewed through the lenses?

h. Use thedirectionsabovetoviewtheletteratthehigherobjectivepowers.Onthedrawing made above,circletheportion oftheletterthatisviewableassuccessivelyhigherpower observationsaremade.Whatis yourconclusionaboutwhathappenswhenhigherpower objectivesare used?

4. TotalMagnificationCalculation:Typically,theocularlensofamicroscopewillbe10x,butit may be higher or lower. The power is recorded on the side of the lens.

a. Whatistheocularlenspowerofthemicroscopethatyouareusing?Itmaybe10xor15x.

Record it in Table 1.

b. The objectivelenses alsohavethemagnificationpowerrecordedontheirsides. What powers do the objectivelenses on the microscope have? Record them in Table 1.

c. Now,calculatethetotalmagnificationoftheviewingareabymultiplyingthepowerof the ocularlenswiththatoftheobjectivelensinuse.Forinstance, ifamicroscopehas a10xmagnificationocular lensanda4xobjectivelensinplaceforviewing,thetotal magnificationwillbe40x(10xmultiplied by4x).Whatotherviewmagnifications are possiblewiththemicroscope?Calculatethetotalmagnificationforeachsetoflensesin Table 1.

Table 1: CalculatingMagnification

Ocular Lens Magnificationx

ObjectiveLenses

Magnification=

Total Magnification

5. Diameter of Field:

a. Withthelow-powerobjective inviewingposition, placeashorttransparentmetricruler on the stage.

b. While viewingtherulerthroughthelenses,measurethelow-powerdiameteroffieldof view in mm. Convert this measurement to μm and record in Table 2.

c. Switchtotheother higherpowerobjectives,noting thediameter,inmm,foreachinTable

2.Convertmeasurementstoμm.Howmightthisinformationbeusefulwhenviewing

microscopic subjects?

Table 2: Diameter of a Viewing Field

Magnification

(ocular x objectivelens’

powers)

mm diameter

of fieldof view

μm diameter *

of fieldof view

Scanning Lens

LowPowerLens

High PowerLens

6. DepthofField: Prepareawetmountslideofthreedifferentlycoloredcrossedthreadsusing the wet-mount techniquedescribed above. Place the slideon the microscope stage with the threadcrossingareainthecenter oftheviewingarea.Focuscarefully,movingthescanning objectivelens up and down, taking care not to break the cover slip.

Record the order of the threads in this table. Note that, when one thread is in focus, the others appear blurred. Why? When you focus on another thread, what happens to the thread that you were viewing?

Depth

ThreadColor

Top

Middle

Bottom

Switch to high power and focus on one thread, then focus on another thread. What do you noticeabout the depth of field?Can you see as much of the thread in focus at the high power as you could at the low power magnification?

7. View an animal cell:

a. Observe the prepared slideunderthe microscope, beginningwiththe scanninglensand then proceedingtohighermagnificationlevels.Locatethenucleus inseveralcells.Locate the cytoplasmandthe plasmamembrane. Ona sheet ofpaper, make a drawingofa few cells, and label the observed parts.

8. View a plant cell:

a. Observe the slide under the microscope, beginning with the scanning lens and then proceeding to higher magnification levels. Locate the cell wall and the nucleusinseveralcells.Makeadrawingofafewcellsandlabeltheobservedparts.

b. Countacolumnofcells,stackedend-to-end,acrossthefield ofvisionunderhigh-power magnification.

c. F. Basedonthefieldofvisionmeasurementyoucalculatedabove,computetheaverage length of one cell in the column of cells with this formula:

μm average length of cell = μm diameter of fieldof view ÷ total number of cells in the column.

d. What differenceswere noted between the animal cells and the plant cells?

e. How do the differencesdictate the form of the organism?

Discussion

A. What is the purpose of staining cells before viewing them under a microscope?

B. Whattypeofmicroscopewouldyouusetoviewthefollowingorganisms? Theremaybemore than one correct response for each.

Strep throat culture

Mitochondria in an animal cell

Structure of a bird feather

Chloroplasts in a leaf cell

Earthworm digestive system

Enterococcusbacteria

DNA structure in the nucleus

Spores from a mushroom

Cells from plant leaf

Herpes simplex

C. Summarize the capabilitiesof each of the microscopes listed in Table 2-3 below.

Table 3: Summary of Microscope Capabilities

Typeof Microscope

TypeofDetection

Beam

MagnificationRange,metric

Examples of ViewableSpecimens

Dissecting

CompoundLight

Scanning electron

Transmission electron

Laboratory Summary

1. What have you learned from doing this laboratory?

2. Why is the informationpresented in this laboratory intrinsic to all future studies in biology?