Daphnia Size and Heart Rate
The next activity is based off a Biology 210A lab activity. In Biology 210A undergraduates
study the impact of caffeine on the heart rate of an arthropod. Below you will find the
instructions for that lab. Using the tools outlined in class, use JMP to analyze the data
from Biology 210A to determine if the distribution of Daphnia heart rates are different for
Daphnia exposed to various concentrations of caffeine. In Appendix A you will find real
record sheets from 210A students.
In this Biology 200 activity you are asked to specifically address the following:
1. Evaluate the design of this study and explain how you might improve it.
#
2. Create JMP output that has summary statistics for the heart rates of Daphnia at
different concentrations of caffeine. Produce graphs that allow you to compare the
heart rate distributions at each concentration. Write down a verbal description of
how the distributions differ among the concentrations (record that in this manual).
#
#
3. Can you conclude that caffeine causes heart rates to increase in Daphnia? #
#
#
4. It is possible that some animals are not sensitive to caffeine. Explain how it might
be possible that Daphnia is not sensitive to caffeine and that any observed
differences that you found in this Daphnia study could be due to chance alone.
#
30
Microscopy#III:#Measurements#(Daphnia'Size#and#Heart#Rate)#
Student#Learning#Outcomes:!
By!the!end!of!this!lab!exercise,!students!should!be!able!to:!
• Accurately!determine!the!size!of!a!microorganism!using!an!ocular!micrometer!and!
stage!micrometer!
• Be!able!to!identify!basic!features!of!Daphnia'magna!!
• Develop!a!hypothesis,!experimental!design!and!perform!an!experiment!using!the!
scientific!method!to!then!obtain!accurate!results!and!conclusion!relating!to!the!
effects!of!caffeine!on!Daphnia!heart!rate!
• Study!the!effects!of!caffeine!on!heart!rate!in!Daphnia'magna!
!
INTRODUCTION#
Daphnia'(common!name!?water!fleas?)!are!microcrustaceans!(related!to!shrimp)!that!have!
a!clear!outside!skeleton!(carapace)!and!jointed!legs.!They!are!often!found!in!freshwater!
and!saline!ponds!and!feed!on!particles!found!floating!in!the!water!(phytoplankton)!but!
the!predominant!foods!are!freeFliving!algae,!bacteria!and!fungi.!In!the!summer!months,!
they!can!often!be!seen!?blooming?!in!ponds!and!lakes!as!the!concentration!of!algae!starts!
to!build!up.!!Daphnia!are!often!used!an!indicator!of!water!quality!by!a!number!of!research!
and!industrial!groups!as!they!have!been!proven!to!be!very!sensitive!to!poor!water!
conditions.!!For!example,!they!are!very!sensitive!to!halide!concentration,!like!the!chloride!
or!fluoride!in!tap!water,!which!are!extremely!toxic!to!Daphnia,!even!more!so!than!to!fish.!!
Figure#1.!Photomicrograph!of!Daphnia,!the!common!water!flea.!Note!the!position!of!the!heart.!
31
#
ACTIVITY#2:!Measuring#the#effects#of#caffeine#on#Daphnia#heart#rate#!
The!heart!is!an!organ!structure!responsible!for!pumping!oxygenated!blood!and!essential!
nutrients!throughout!the!body.!!The!objective!of!this!experiment!is!to!test!whether!
caffeine!and!ethanol!have!an!effect!on!heart!rate,!using!the!freshwater!crustacean,!
Daphnia,!as!an!experimental!model!system.!!
There!are!various!factors!that!influence!heart!rate!in!individuals.!!Stress,!heart!structural!
abnormalities,!as!well!as!environmental!factors!which!include!temperature!and!various!
chemicals!play!a!role!in!altering!heart!rate.!!!
Like!any!model!system,!there!are!advantages!and!disadvantages!to!Daphnia.!They!are!
fairly!easy!to!keep,!easy!to!study,!and!inexpensive.!However,!they!are!evolutionarily!farF
removed!from!humans,!so!you!need!to!be!cautious!when!interpreting!your!results.!What!
happens!when!Daphnia!are!exposed!to!caffeine!may!or!may!not!have!similarities!to!when!
humans!drink!coffee.!
The!outer!carapace!of!Daphnia!is!transparent,!so!you!can!see!through!to!the!internal!
organs!(Figure#1).!!This!allows!you!to!monitor!the!heart!rate!of!individual!Daphnia!that!
you!observe!with!a!compound!microscope.!!Larger!than!a!Plasmodium,!this!multicellular!
animal!is!roughly!the!size!of!a!pinhead!and!can!be!seen!darting!about!under!the!
microscope.!!Using!a!compound!light!microscope,!individual!Daphnia!can!be!viewed!
under!low!power!with!the!help!of!a!special!microscope!slide!known!as!a!depression#
slide.!The!depression!slide!has!a!polished,!concave!depression!at!the!center!that!can!hold!
a!large!drop!of!water.!A!coverslip!can!be!placed!on!top!of!the!slide!to!allow!for!easy!
viewing!of!Daphnia!without!physically!damaging!this!microorganism.!!
*Measurements!should!be!taken!quickly,!so!that!the!Daphnia!does!not!become!stressed!in!
the!small!volume!of!water!and!students!should!avoid!heating!the!solution!with!your!
illuminating!light!as!Daphnia!heart!rate!is!also!temperatureFsensitive.!!
Materials:##(2F3!students!per!group)!
•
•
•
•
•
•
•
•
Daphnia'in!culture!liquid!(per!group)!
transfer!pipettes!!
A!clean!depression!slide!!
Lens!wipe!or!tissue!paper!
A!small!container!for!“used”!Daphnia'
Spring!water!(or!dechlorinated!tap!water)Fkept!at!20οC!in!water!bath'
Caffeine!(200!mg/L!stock!solution)!
Microcentrifuge!tubes/tube!rack!
32
• PF1000!micropipette!and!fixed!volume!micropipette!(50!µl)!and!sterile!tips!
• Compound!microscope!
Observation:#
You!have!observed!Daphnia!in!the!previous!activity!using!prepared!slides.!!Remember!the!
location!of!the!heart!in!this!activity!and!also!note!the!fact!that!live!Daphnia!are!motile!!You!
will!count!the!number!of!heartbeats!in!ten!seconds!in!the!absence!of!any!chemicals!and!
then!determine!whether!this!rate!will!change!in!the!presence!of!caffeine.!Considering!
your!initial!knowledge!of!caffeine,!decide!what!effect!it!might!have!on!Daphnia.!
Stimulants!act!to!speed!up!the!BPM!(beats!per!minute)!while!depressants!act!to!slow!
down!the!BPM.!
!
Develop#a#Hypothesis:!
Before!you!begin!your!experiment,!develop!a!hypothesis!about!the!effect!of!
caffeine/ethanol!on!the!heart!rate!of!Daphnia.!!Write!your!hypothesis!as!a!prediction,!
clearly!stating!the!result!you!expect!to!see!if!Daphnia!are!subject!to!either!caffeine!or!
ethanol!(Each!group!will!look!at!only!one!of!these!factors!so!your!hypothesis!is!NOT!
whether!caffeine!or!ethanol!will!have!an!effect,!this!is!too!general—state!instead!
specifically!if!caffeine!(or!ethanol)!will!increase!or!decrease!heart!rate!and!at!what!
concentration!might!you!expect!to!see!the!greatest!effect.!!
Protocol:###
1. Starting!with!the!200!mg/L!stock!solution!of!caffeine!prepare!six!serial!10Ffold!
dilutions,!with!each!dilution!in!a!total!of!500!µL.!!Label#each#tube!carefully!to!help!
you!keep!track!of!each!solution.!!Be!sure!to!use!the!*spring!water!provided!and!
place#each#dilution#tube#in#the#20ο C#water#bath#until#that#particular#tube#is#to#be#
used!in!your!experiment.#
(Remember:!use!spring!water!to!dissolve!the!caffeine.!Tap!water!usually!contains!chlorine!(and/or!chloramine)!
as!a!disinfectant,!which!will!kill!Daphnia!(and!other!aquatic!organisms).!
#
2. Keep#the#light#for#your#microscope#OFF#as#much#as#possible#to#avoid#
overheating#your#Daphnia!#
#
3. Using!a!clean!transfer!pipette,!carefully!transfer!a!Daphnia!onto!a!depression!slide!
and!absorb!the!excess!water!with!a!small!amount!of!cotton!wool.!!Quickly!add!
ONE'drop!of!liquid!(initially!spring!water!only:!0!mg/L).!Keep!the!drop!small!so!
that!the!Daphnia!cannot!swim!out!of!your!field!of!view. Pipette!carefully!to!avoid!
33
introducing!air!bubbles!beneath!the!carapace!of!the!Daphnia.!(Air!bubbles!make!
Daphnia!float!at!the!surface,!unable!to!swim,!which!will!eventually!kill!them.) Place
a cover slip on top.#
#
4. Place!the!slide!under!the!microscope!and!focus!on!the!Daphnia!so!that!you!can!see!
the!beating!heart!using!the!scanning!objective!(4X)!(Remember:!its!heart!is!on!its!
back!)!
!
5. Count!the!number!of!heart!beats!that!occur!in!10!seconds.!Have!your!lab!partner!
time!
ten!seconds!for!you!as!you!count!heartbeats.!You!want!to!take'your'measurements'
quickly,!so!that!the!Daphnia!does!not!become!stressed!in!the!small!volume!of!water.!
!
6. Record!the!number!of!heart!beats!in!the!data!table!below!for!each!Trial.!Take!at!
least!three#separate!heart!rate!measurements!for!each!individual!Daphnia!and!
calculate!the!average!of!the!three!measurements.!
!
7. When!you!have!finished!recording!the!heart!rate!in!water!(the!Control!solution),!
use!a!small!amount!of!cotton!wool!to!absorb!the!spring!water!from!the!depression!
slide!cavity!and!then!add!ONE'drop!of!the!0.001#mg/L#caffeine#solution!to!the!
slide.!Turn!the!light!OFF!and!wait!30!seconds.!
!
8. Turn!the!light!back!on!and!count!the!number!of!heart!beats!for!10!seconds!again,!
repeating!at!least!3!times.!Record!your!results!in!the!data!table.!
!
9. Rinse!the!Daphnia'into!the!“used”!container,!then!repeat!steps!#!3F9!with!a!new!
Daphnia'for!each!new!concentration!of!caffeine.!Remember!to!use!a!small!amount!
of!cotton!wool!to!absorb!the!excess!run!and!that!for!each!consecutive!run,!you!will!
then!quickly!add!a!drop!of!the!next!concentrated!solution!of!caffeine,!working!
your!way!up!to!the!most!concentrated!solution:!in!other!words!0!mg/L!caffeine!
(water!only)!first,!followed!by!0.001!mg/L,!0.01!mg/L,!0.1!mg/L,!1.0!mg/L,!10!mg/L,!
and!100!mg/L!respectively.!!Use!a!fresh!pipette!with!each!new!concentration.!
DATA:!
1. In!the!table!below,!write!the!number!of!heartbeats!counted!in!ten!(10)!seconds.!You!
will!count!the!number!of!heartbeats!three!separate!times!per!individual!Daphnia!
34
and!record!them!as!separate!trials.!Convert!each!rate!into!heartbeats/minute!
(multiply!each!number!by!6).!!Write!the!average!number!of!heartbeats!per!minute!
(60!seconds)!for!each!concentration!of!caffeine!including!the!control!(water!only).!!
Sample!of!the!Results!Table:!Effect!of!Caffeine!on!Daphnia!Heart!Rate!
Concentration#of#
Caffeine#
Observed#
Heart#beats/#10#seconds#
Computed#
Heart#beats/#60#seconds#
Mean#
Trial'#1'
Trial'#2'
Trial'#3'
Trial'#1'
Trial'#2'
Trial'#3'
(*BPM)#
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
0!mg/L!(control)!
!
0.001!mg/L!
!
!
0.01!mg/L!
!
!
0.1!mg/L!
!
!
#
Assignment 2: Daphnia Measurements
Write a short report (less than one page, including tables/figures) that addresses the
question:
Does caffeine affect Daphnia heart rates?
Write the report in a style that tells the reader what was discovered. Selectively use key
graphs and a small set of specific statistics in your description of the findings. Any graph
or set of statistics presented must be discussed in the text of the report. Groups may
choose to submit a group report.
A strong report will be focused, without redundancy, contain at least one strong graphic
that supports the points being made, summary statistics to support general descriptions,
and a narrative (writing) that tells a coherent story about what was discovered. In this
case, the story should be useful in deciding if there is a problem with using various labs
for the collection of the calcium and phosphorus data.
35
Daphnia Size and Heart Rate
The next activity is based off a Biology 210A lab activity. In Biology 210A undergraduates
study the impact of caffeine on the heart rate of an arthropod. Below you will find the
instructions for that lab. Using the tools outlined in class, use JMP to analyze the data
from Biology 210A to determine if the distribution of Daphnia heart rates are different for
Daphnia exposed to various concentrations of caffeine. In Appendix A you will find real
record sheets from 210A students.
In this Biology 200 activity you are asked to specifically address the following:
1. Evaluate the design of this study and explain how you might improve it.
#
2. Create JMP output that has summary statistics for the heart rates of Daphnia at
different concentrations of caffeine. Produce graphs that allow you to compare the
heart rate distributions at each concentration. Write down a verbal description of
how the distributions differ among the concentrations (record that in this manual).
#
#
3. Can you conclude that caffeine causes heart rates to increase in Daphnia? #
#
#
4. It is possible that some animals are not sensitive to caffeine. Explain how it might
be possible that Daphnia is not sensitive to caffeine and that any observed
differences that you found in this Daphnia study could be due to chance alone.
#
30
Microscopy#III:#Measurements#(Daphnia'Size#and#Heart#Rate)#
Student#Learning#Outcomes:!
By!the!end!of!this!lab!exercise,!students!should!be!able!to:!
• Accurately!determine!the!size!of!a!microorganism!using!an!ocular!micrometer!and!
stage!micrometer!
• Be!able!to!identify!basic!features!of!Daphnia'magna!!
• Develop!a!hypothesis,!experimental!design!and!perform!an!experiment!using!the!
scientific!method!to!then!obtain!accurate!results!and!conclusion!relating!to!the!
effects!of!caffeine!on!Daphnia!heart!rate!
• Study!the!effects!of!caffeine!on!heart!rate!in!Daphnia'magna!
!
INTRODUCTION#
Daphnia'(common!name!?water!fleas?)!are!microcrustaceans!(related!to!shrimp)!that!have!
a!clear!outside!skeleton!(carapace)!and!jointed!legs.!They!are!often!found!in!freshwater!
and!saline!ponds!and!feed!on!particles!found!floating!in!the!water!(phytoplankton)!but!
the!predominant!foods!are!freeFliving!algae,!bacteria!and!fungi.!In!the!summer!months,!
they!can!often!be!seen!?blooming?!in!ponds!and!lakes!as!the!concentration!of!algae!starts!
to!build!up.!!Daphnia!are!often!used!an!indicator!of!water!quality!by!a!number!of!research!
and!industrial!groups!as!they!have!been!proven!to!be!very!sensitive!to!poor!water!
conditions.!!For!example,!they!are!very!sensitive!to!halide!concentration,!like!the!chloride!
or!fluoride!in!tap!water,!which!are!extremely!toxic!to!Daphnia,!even!more!so!than!to!fish.!!
Figure#1.!Photomicrograph!of!Daphnia,!the!common!water!flea.!Note!the!position!of!the!heart.!
31
#
ACTIVITY#2:!Measuring#the#effects#of#caffeine#on#Daphnia#heart#rate#!
The!heart!is!an!organ!structure!responsible!for!pumping!oxygenated!blood!and!essential!
nutrients!throughout!the!body.!!The!objective!of!this!experiment!is!to!test!whether!
caffeine!and!ethanol!have!an!effect!on!heart!rate,!using!the!freshwater!crustacean,!
Daphnia,!as!an!experimental!model!system.!!
There!are!various!factors!that!influence!heart!rate!in!individuals.!!Stress,!heart!structural!
abnormalities,!as!well!as!environmental!factors!which!include!temperature!and!various!
chemicals!play!a!role!in!altering!heart!rate.!!!
Like!any!model!system,!there!are!advantages!and!disadvantages!to!Daphnia.!They!are!
fairly!easy!to!keep,!easy!to!study,!and!inexpensive.!However,!they!are!evolutionarily!farF
removed!from!humans,!so!you!need!to!be!cautious!when!interpreting!your!results.!What!
happens!when!Daphnia!are!exposed!to!caffeine!may!or!may!not!have!similarities!to!when!
humans!drink!coffee.!
The!outer!carapace!of!Daphnia!is!transparent,!so!you!can!see!through!to!the!internal!
organs!(Figure#1).!!This!allows!you!to!monitor!the!heart!rate!of!individual!Daphnia!that!
you!observe!with!a!compound!microscope.!!Larger!than!a!Plasmodium,!this!multicellular!
animal!is!roughly!the!size!of!a!pinhead!and!can!be!seen!darting!about!under!the!
microscope.!!Using!a!compound!light!microscope,!individual!Daphnia!can!be!viewed!
under!low!power!with!the!help!of!a!special!microscope!slide!known!as!a!depression#
slide.!The!depression!slide!has!a!polished,!concave!depression!at!the!center!that!can!hold!
a!large!drop!of!water.!A!coverslip!can!be!placed!on!top!of!the!slide!to!allow!for!easy!
viewing!of!Daphnia!without!physically!damaging!this!microorganism.!!
*Measurements!should!be!taken!quickly,!so!that!the!Daphnia!does!not!become!stressed!in!
the!small!volume!of!water!and!students!should!avoid!heating!the!solution!with!your!
illuminating!light!as!Daphnia!heart!rate!is!also!temperatureFsensitive.!!
Materials:##(2F3!students!per!group)!
•
•
•
•
•
•
•
•
Daphnia'in!culture!liquid!(per!group)!
transfer!pipettes!!
A!clean!depression!slide!!
Lens!wipe!or!tissue!paper!
A!small!container!for!“used”!Daphnia'
Spring!water!(or!dechlorinated!tap!water)Fkept!at!20οC!in!water!bath'
Caffeine!(200!mg/L!stock!solution)!
Microcentrifuge!tubes/tube!rack!
32
• PF1000!micropipette!and!fixed!volume!micropipette!(50!µl)!and!sterile!tips!
• Compound!microscope!
Observation:#
You!have!observed!Daphnia!in!the!previous!activity!using!prepared!slides.!!Remember!the!
location!of!the!heart!in!this!activity!and!also!note!the!fact!that!live!Daphnia!are!motile!!You!
will!count!the!number!of!heartbeats!in!ten!seconds!in!the!absence!of!any!chemicals!and!
then!determine!whether!this!rate!will!change!in!the!presence!of!caffeine.!Considering!
your!initial!knowledge!of!caffeine,!decide!what!effect!it!might!have!on!Daphnia.!
Stimulants!act!to!speed!up!the!BPM!(beats!per!minute)!while!depressants!act!to!slow!
down!the!BPM.!
!
Develop#a#Hypothesis:!
Before!you!begin!your!experiment,!develop!a!hypothesis!about!the!effect!of!
caffeine/ethanol!on!the!heart!rate!of!Daphnia.!!Write!your!hypothesis!as!a!prediction,!
clearly!stating!the!result!you!expect!to!see!if!Daphnia!are!subject!to!either!caffeine!or!
ethanol!(Each!group!will!look!at!only!one!of!these!factors!so!your!hypothesis!is!NOT!
whether!caffeine!or!ethanol!will!have!an!effect,!this!is!too!general—state!instead!
specifically!if!caffeine!(or!ethanol)!will!increase!or!decrease!heart!rate!and!at!what!
concentration!might!you!expect!to!see!the!greatest!effect.!!
Protocol:###
1. Starting!with!the!200!mg/L!stock!solution!of!caffeine!prepare!six!serial!10Ffold!
dilutions,!with!each!dilution!in!a!total!of!500!µL.!!Label#each#tube!carefully!to!help!
you!keep!track!of!each!solution.!!Be!sure!to!use!the!*spring!water!provided!and!
place#each#dilution#tube#in#the#20ο C#water#bath#until#that#particular#tube#is#to#be#
used!in!your!experiment.#
(Remember:!use!spring!water!to!dissolve!the!caffeine.!Tap!water!usually!contains!chlorine!(and/or!chloramine)!
as!a!disinfectant,!which!will!kill!Daphnia!(and!other!aquatic!organisms).!
#
2. Keep#the#light#for#your#microscope#OFF#as#much#as#possible#to#avoid#
overheating#your#Daphnia!#
#
3. Using!a!clean!transfer!pipette,!carefully!transfer!a!Daphnia!onto!a!depression!slide!
and!absorb!the!excess!water!with!a!small!amount!of!cotton!wool.!!Quickly!add!
ONE'drop!of!liquid!(initially!spring!water!only:!0!mg/L).!Keep!the!drop!small!so!
that!the!Daphnia!cannot!swim!out!of!your!field!of!view. Pipette!carefully!to!avoid!
33
introducing!air!bubbles!beneath!the!carapace!of!the!Daphnia.!(Air!bubbles!make!
Daphnia!float!at!the!surface,!unable!to!swim,!which!will!eventually!kill!them.) Place
a cover slip on top.#
#
4. Place!the!slide!under!the!microscope!and!focus!on!the!Daphnia!so!that!you!can!see!
the!beating!heart!using!the!scanning!objective!(4X)!(Remember:!its!heart!is!on!its!
back!)!
!
5. Count!the!number!of!heart!beats!that!occur!in!10!seconds.!Have!your!lab!partner!
time!
ten!seconds!for!you!as!you!count!heartbeats.!You!want!to!take'your'measurements'
quickly,!so!that!the!Daphnia!does!not!become!stressed!in!the!small!volume!of!water.!
!
6. Record!the!number!of!heart!beats!in!the!data!table!below!for!each!Trial.!Take!at!
least!three#separate!heart!rate!measurements!for!each!individual!Daphnia!and!
calculate!the!average!of!the!three!measurements.!
!
7. When!you!have!finished!recording!the!heart!rate!in!water!(the!Control!solution),!
use!a!small!amount!of!cotton!wool!to!absorb!the!spring!water!from!the!depression!
slide!cavity!and!then!add!ONE'drop!of!the!0.001#mg/L#caffeine#solution!to!the!
slide.!Turn!the!light!OFF!and!wait!30!seconds.!
!
8. Turn!the!light!back!on!and!count!the!number!of!heart!beats!for!10!seconds!again,!
repeating!at!least!3!times.!Record!your!results!in!the!data!table.!
!
9. Rinse!the!Daphnia'into!the!“used”!container,!then!repeat!steps!#!3F9!with!a!new!
Daphnia'for!each!new!concentration!of!caffeine.!Remember!to!use!a!small!amount!
of!cotton!wool!to!absorb!the!excess!run!and!that!for!each!consecutive!run,!you!will!
then!quickly!add!a!drop!of!the!next!concentrated!solution!of!caffeine,!working!
your!way!up!to!the!most!concentrated!solution:!in!other!words!0!mg/L!caffeine!
(water!only)!first,!followed!by!0.001!mg/L,!0.01!mg/L,!0.1!mg/L,!1.0!mg/L,!10!mg/L,!
and!100!mg/L!respectively.!!Use!a!fresh!pipette!with!each!new!concentration.!
DATA:!
1. In!the!table!below,!write!the!number!of!heartbeats!counted!in!ten!(10)!seconds.!You!
will!count!the!number!of!heartbeats!three!separate!times!per!individual!Daphnia!
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and!record!them!as!separate!trials.!Convert!each!rate!into!heartbeats/minute!
(multiply!each!number!by!6).!!Write!the!average!number!of!heartbeats!per!minute!
(60!seconds)!for!each!concentration!of!caffeine!including!the!control!(water!only).!!
Sample!of!the!Results!Table:!Effect!of!Caffeine!on!Daphnia!Heart!Rate!
Concentration#of#
Caffeine#
Observed#
Heart#beats/#10#seconds#
Computed#
Heart#beats/#60#seconds#
Mean#
Trial'#1'
Trial'#2'
Trial'#3'
Trial'#1'
Trial'#2'
Trial'#3'
(*BPM)#
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
0!mg/L!(control)!
!
0.001!mg/L!
!
!
0.01!mg/L!
!
!
0.1!mg/L!
!
!
#
Assignment 2: Daphnia Measurements
Write a short report (less than one page, including tables/figures) that addresses the
question:
Does caffeine affect Daphnia heart rates?
Write the report in a style that tells the reader what was discovered. Selectively use key
graphs and a small set of specific statistics in your description of the findings. Any graph
or set of statistics presented must be discussed in the text of the report. Groups may
choose to submit a group report.
A strong report will be focused, without redundancy, contain at least one strong graphic
that supports the points being made, summary statistics to support general descriptions,
and a narrative (writing) that tells a coherent story about what was discovered. In this
case, the story should be useful in deciding if there is a problem with using various labs
for the collection of the calcium and phosphorus data.
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c. Can you identify any questionable statistical practice(s) that these authors and
their peer-reviewers found to be acceptable?
4. In 1898, Hermon Bumpus collected data on one of the first examples of natural
selection directly observed in nature. Immediately following a bad winter storm, 136
English house sparrows were collected and brought indoors. Of these, 72 subsequently
recovered, but 64 died. Bumpus made several measurements on all of the birds, and he
was able to demonstrate strong natural selection on some of the traits as a result of this
storm.
Bumpus published all of his data, and they are given in the file "Bumpus.csv." Determine
whether the birds that survived differ from the dead birds for each of the following traits:
a. Total length
b. Sex
c. Skull width
d. Beak and Head length
e. Weight
f. Age
5. Reminder: This is B level assignment. Return to the Daphnia and caffeine study. Write
a one page short report that addresses the question: Does exposure to 0.001mg/L
caffeine increase the heart rate of Daphnia? Utilize the Fall 2012 data file, found on the
class website. Also, write another separate and independent short report that addresses
the question: Does exposure to 1.0mg/L caffeine increase the heart rate of Daphnia?
Assume these studies were conducted with the same protocol as the study reviewed in
the earlier chapter, except individual Daphnia were exposed to only one concentration of
caffeine, treatments were randomly assigned, and the observers were blinded to the
concentration.
Use the guidelines for short-reports.
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