effect of caffeine on body.pdf

7/28/2019 effect of caffeine on body.pdf

1/17

BIOLOGY LAB REPORT

TITLE : THE EFFECT OF CAFFEINE ON HEART RATE

PREPARED BY :

I/C NUMBER :

STUDENT ID :

GROUP :

LECTURERS NAME :

PRACTICAL DATE :

SUBMISSION DATE :


2/17

OBJECTIVE

To investigate the effect of caffeine on the heart rate of Daphnia (water fleas). To highlight experimental and investigative skills.

Introduction

DAPHNIA(1)

Figure 1 : Daphnia(2)

Daphnia is a large genus comprising about 150 species, belonging to the cladoceran family

Daphniidae . Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. They are

commonly called water fleas because of their saltatory swimming .They live in various aquatic

environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers. The most

important features of Daphnia are the compound eyes, the second antennae, and a pair of

abdominal setae. In many species, the carapace is translucent or nearly so and as a result they make

excellent subjects for the microscope as one can observe the beating heart.

Even under relatively low power microscope, the eye being moved by the ciliary muscles can be

seen, as well as its heart beat. The heart is at the top of the back, behind the head, and the average

heart rate is approximately 180 bpm under normal conditions. Daphnia, like many animals, are prone

to alcohol intoxication, and make excellent subjects for studying the effects of the depressant on

the nervous system and due to the translucent exoskeleton, and the visibly altered heart rate.
http://en.wikipedia.org/wiki/Cladocerahttp://en.wikipedia.org/wiki/Daphniidaehttp://en.wikipedia.org/wiki/Planktonhttp://en.wikipedia.org/wiki/Crustaceanhttp://en.wikipedia.org/wiki/Water_fleahttp://en.wikipedia.org/wiki/Saltation_(gait)http://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Swamphttp://en.wikipedia.org/wiki/Fresh_waterhttp://en.wikipedia.org/wiki/Compound_eyehttp://en.wikipedia.org/wiki/Antenna_(biology)http://en.wikipedia.org/wiki/Setahttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Microscopyhttp://en.wikipedia.org/wiki/Ciliary_musclehttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Nervous_systemhttp://en.wikipedia.org/wiki/Heart_ratehttp://en.wikipedia.org/wiki/Heart_ratehttp://en.wikipedia.org/wiki/Nervous_systemhttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Ciliary_musclehttp://en.wikipedia.org/wiki/Microscopyhttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Setahttp://en.wikipedia.org/wiki/Antenna_(biology)http://en.wikipedia.org/wiki/Compound_eyehttp://en.wikipedia.org/wiki/Fresh_waterhttp://en.wikipedia.org/wiki/Swamphttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Saltation_(gait)http://en.wikipedia.org/wiki/Water_fleahttp://en.wikipedia.org/wiki/Crustaceanhttp://en.wikipedia.org/wiki/Planktonhttp://en.wikipedia.org/wiki/Daphniidaehttp://en.wikipedia.org/wiki/Cladocera


3/17

They are tolerant of being observed live under a cover slip and appear to suffer no harm when

returned to open water.

Figure 2 : Reproduction of Daphnia(2)

Daphnia reproduce parthenogenetically usually in the spring until the end of the summer. In

addition to the production of eggs capable of overwintering, this switch to sexual reproduction has

also been proposed to allow greater offspring variation that is useful in varied or unpredictable

conditions.

The lifespan of a Daphnia does not exceed one year and is largely temperature dependent.For example, individual organisms can live up to 108 days at 3 C (37 F) while some organisms live

for only 29 days at 28 C (82 F). A clear exception to this trend is during the winter time in which

harsh conditions limit the population in which females have been recorded to live for over six

months. These females generally grow at a slower rate but in the end are larger than ones under

normal conditions.

Sometimes Daphnia may be used in certain environments to test the effects oftoxins on

an ecosystem. This makes Daphnia an indicator species, particularly useful in that area because of its

short lifespan and reproductive capabilities. As they are nearly transparent, their internal organs are

easy to study in live specimens . They are often fed to tadpoles or small species of amphibians such

as the African Dwarf Frog. Daphnia are also a popular live food in tropical and marine fish keeping.
http://en.wikipedia.org/wiki/Parthenogenesishttp://en.wikipedia.org/wiki/Toxinhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Indicator_specieshttp://en.wikipedia.org/wiki/African_Dwarf_Froghttp://en.wikipedia.org/wiki/African_Dwarf_Froghttp://en.wikipedia.org/wiki/Indicator_specieshttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Toxinhttp://en.wikipedia.org/wiki/Parthenogenesis


4/17

CAFFEINE(3)

Figure 3 : Caffeine formula(2)

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found

in seeds, leaves, and fruit of some plants.Caffeine acts as a natural pesticide that paralyzes and kills

certain insects feeding on the plants. It is most commonly consumed by humans in infusions

extracted from the bean of the coffee plant and the leaves of the tea bush, as well as from various

foods and drinks containing products derived from the kolanut.

Figure 4 : Side effects of Caffeine in human(2)

Figure 5 : Effect of moderate caffeine consumption(2)
http://en.wikipedia.org/wiki/Crystallinehttp://en.wikipedia.org/wiki/Xanthinehttp://en.wikipedia.org/wiki/Alkaloidhttp://en.wikipedia.org/wiki/Stimulanthttp://en.wikipedia.org/wiki/Coffea_arabicahttp://en.wikipedia.org/wiki/Camellia_sinensishttp://en.wikipedia.org/wiki/Camellia_sinensishttp://en.wikipedia.org/wiki/Coffea_arabicahttp://en.wikipedia.org/wiki/Stimulanthttp://en.wikipedia.org/wiki/Alkaloidhttp://en.wikipedia.org/wiki/Xanthinehttp://en.wikipedia.org/wiki/Crystalline


5/17

Caffeine can have both positive and negative effects on anxiety disorders depending on the

dose. At high doses ( greater than 300 mg) , it can both cause and make anxiety worse. At low doses

it may reduce symptoms of anxiety. Caffeine withdrawal, on the other hand, can cause an increase in

anxiety level. In moderate doses caffeine typically does not affect learning or memory. It does

however improve cognitive function in people who are fatigued, due to its effect on alertness. Some

studies have however found a modest protective against Alzheimer disease, but the evidence is

inconclusive.

Caffeine is also used as a flavour enhancer in cola and other soft drinks also it has medicinal

uses in aspirin preparations and is found in weight-loss drug and as a stimulant in normal people in

everyday to keep them alert in their work.
http://en.wikipedia.org/wiki/Effect_of_caffeine_on_memoryhttp://en.wikipedia.org/wiki/Alzheimer_diseasehttp://en.wikipedia.org/wiki/Alzheimer_diseasehttp://en.wikipedia.org/wiki/Effect_of_caffeine_on_memory


6/17

Problem Statement :

How does the concentration of caffeine affect the heart rate of Daphnia?

Hypothesis :

The higher the caffeine concentration, the higher the number of heart beat of Daphnia.

Variables :

Types of Variables Ways to control the variables

Manipulated Variable:

Concentration of caffeineUse different amount of caffeine powder,

measured with electronic balance and mix with

fixed amount of water needed.

Responding Variables:

Number of heart beat of Daphnia/ 15 secondsNumber of heart beat of Daphnia was calculated

by making marks on paper while counting the

heart beat and later calculate and record.

Fixed Variables:

Temperature of surrounding of Daphnia

Daphnia used

Hold experiment at room temperature

throughout experiment

Use same Daphnia throughout the experiment.


7/17

Apparatus

Stop watch, dropper, cavity slide, microscope, measuring cylinder, electronic balance, 100ml beaker

Materials

Daphnia, distilled water, coffee powder, cotton wool, tissue paper

Technique used

The Daphnia was observed under light microscope. The heart beats off Daphnia was counted directly

by observing the heart of the transparent Daphnia by one person. The experiment was done by each

group with different concentration to prevent contamination of different concentration of caffeine

on Daphnia, thus result in alteration of result, causing less validity of result.


8/17

Procedure :

1. A cotton wool was placed on cavity of microscope slide to restrict the movement ofDaphnia.

2. A daphnia was transferred from a beaker containing pond water to the cavity ofmicroscope slide using a dropper.

3. Excess liquid was removed using tissue paper. Two drops of distilled water was placedon Daphnia specimen using dropper.

4. Another slide was placed under the specimen slide to act as heat sink, works bypreventing loss of water.

5. The slide was then placed on microscope stage.6. Daphnia was examined in low power objective lens and the location of eye, heart

and other part was determined. The heart of Daphnia was observed .

7. A stop clock was used to record the number of heartbeats for every 15 seconds for 10minutes. Heartbeats were counted under normal condition (distilled water) at

intervals of 2 minutes over a 10 minute period. Daphnias heart rate was counted

within 15 seconds for every 2 minutes. A pencil was tapped by observant on a piece of

paper and the pencil marks was counted at the end of the time period.

8. It is a good idea to do a blind study to avoid bias in the results.9.

Different caffeine concentration was prepared using coffee powder. 0.1g of coffeepowder was diluted in 100ml for preparation of 1% of caffeine concentration.

10.Step 8 was repeated using of 0.4g, 0.6g and 0.8g coffee powder and diluted with100ml for preparation of 0.4% , 0.6% and 0.8%.

11.Steps 1 until 7 was repeated using same Daphnia under different concentration ofcaffeine as stated in table below.

12.At the end of the experiment, the Daphnia was returned to the stock culture.13.

The results were tabulated.

14.The increase in heart rate of Daphnia was obtained by calculating the difference in theheart rate of Daphnia before and after put in targeted solution.

15.A graph of time against heart rate of Daphnia was plotted.16.A bar graph plotted for caffeine concentration against number of heart beat.


9/17

RESULTS

DATA COLLECTION

Number of heart beat/ 15 seconds

Length of time in solution /

minutes (min)

2 4 6 8 10 Mean

Treatment Caffeine

(0.4%)

53 54 56 56 58 55.4

Caffeine

(0.6%)

59 60 61 63 63 61.2

Caffeine(0.8%)

62 65 65 69 68 65.8

Caffeine

(1.0%)

73 73 74 76 75 74.2

Mean 61.75 63 64 66 66

Control 56 55 55 54 54 54.8

Control 67 67 66 64 65 65.8

Control 63 65 65 62 64 63.8

Control 66 61 62 64 65 63.6

Mean 63 62 62 61 62

Table 1 : Treatment used for 10 minutes against number of heart beat


10/17

58

59

60

61

62

63

64

65

66

67

2 4 6 8 10

NumberofHeartbeat/15seond

s

Time (min)

Time against Number of Hearbeat/15 seconds

Control

With Caffeine

Concentration

Graph 1 : Time(min) against number of heartbeat / 15 seconds

Graph 2 : Caffeine concentration (%) against number of heart beat/15 seconds


11/17

DISCUSSION

Analysis of data

An experiment was held to determine the effect of caffeine concentration on number of heart beat

of Daphnia. A Daphnia was obtained from pond water using dropper and placed inside cavity of slide.

Cotton wool is used to restrict the movement of Daphnia. The heartbeat of Daphnia in distilled water

was observed and recorded for ten minutes and for every 2 minutes, it was recorded for 15 seconds.

This step was carried out with different concentration of caffeine solution that is diluted according to

the masses in procedure above. The heart beat was recorded and at last, both results were

compared. Used Daphnia was returned to the pond water, reducing ethical issues. Since usage of

higher concentration of caffeine will kill the Daphnia, thus solution used is diluted first and the

highest concentration used is 1%.

In graph 2, there is steady increase of heart beat number with caffeine concentration from

0.4% to 0.8%. However, there is tremendous increase from 0.8% to 1.0% caffeine concentration. This

may due to the Daphnia being immersed too long in caffeine solution before the heart beat is

calculated. Another possible cause is may be the caffeine concentration higher than stated value as

the solution is being added without wiped first for preventing the Daphnia from die.

At the beginning of the experiment, the heartbeats of Daphnia is obtained by calculating the

heartbeats of Daphnia in 15 seconds timed by a stopwatch, while observing under light microscope.

Without the presence of caffeine (in distilled water), the initial heartbeat of Daphnia obtained by

making marks on paper and counting it. Since every group is doing control study, thus all readings

were collected and the mean is obtained. Restricting the Daphnia using cotton wool from swimming

around increase the validity of data as the observer can calculate the heart beat with full

concentration. It also can be observed that the number of heart beat of Daphnia in distilled water

decreasing, remaining the same and then decrease again and at last increase. It shows that the heart

beat of Daphnia in distilled water is also altered and since the Daphnia used are not same, thus the

data is taken for mean.


12/17

The heart beat number before the Daphnia is soaked in concentrated but still diluted caffeine

solution has an obvious effect. This can be seen in Graph 1. The number of heart beat of Daphnia

with caffeine water is higher that without caffeine (control which is distilled water). This perfectly

shows that caffeine will increase number of heart beat of Daphnia (likewise in human). It is also can

be observed as time increases the number of heart beat also increase. But at 8th

minute till 10th

minute it can be seen that the number of heart beat stays same. This may be due to maximum

tolerance of Daphnia towards the caffeine concentration. The Daphnia also may suffer from stress

due to the culture solution. It is also possible that not same species used by all the group. Thus it can

be concluded that different Daphnia species have different tolerance toward caffeine concentration,

results in effecting the data.

Thus as a conclusion, it can be said that increase in caffeine concentration will increase

number of heart beat off Daphnia over time. There is clear difference between number of heart beat

when the Daphnia was cultured in caffeine solution and distilled water. This further stresses that the

presence of caffeine will affect the heart beat of Daphnia. This can be said that the caffeine is

working as a stimulant thus increasing the number of heart beat.


13/17

Evaluation

Limitation and improvement

Several limitation are found in this experiment. Sources of error can be avoided totally at times or

reduced to minimum most of the time. But, in this experiment , the limitations are bit harder to

overcome. The daphnia used in experiment may suffer from a genetic defect or have an abnormally

high or low tolerance to caffeine, leading to inaccurate results. Thus, using one daphnia for control

and the same daphnia for specific concentration of caffeine and finding the mean for both constant

values and different caffeine concentration minimizing inaccuracy of data.

Another limitation is there may be some error in calculating the heart beats of Daphnia. Since

the experiment were done by a group of student consisting three, it is possible for human error to

happen. Stopwatch may be start late or earlier than stated. The observer also may start counting the

heart beat before the stop clock switch on and stop later after the stop clock is stopped. Counting of

the pencil marks also can be limited since in the rush of plotting the marks, the points may overlap

causing the reader to not to able to count the overlapping point, resulting in inaccuracy of result.

Taking mean reading (for 5 readings) may increase the data improvement.

Furthermore, using heat sink to keep the Daphnia in a cool environment is not accurate

because as the water eventually evaporate over time because of the microscopes light, the

Daphnias environment is warmer resulting in a higher initial heart rate as usual. Heart rate of

Daphnia may increased not only due to deprivation of water but also putting it into new environment

(caffeine) might increase the stress level of the Daphnia. This is overcome by putting drops of water

in between some time, thus decreasing the effect of water deprivation, improving the data.


14/17

Validity and reability

For ensure the validity of the results, only one Daphnia was used per group and other groups used

same size of Daphnia as possible as can. Before the experiment was carried out with caffeine

solution, the Daphnias heart beat was determined with distilled water as constant and the average

reading was obtained. Heart beat of Daphnia when cultured with caffeine solution was obtained and

average reading was recorded. Since only one Daphnia is used , thus it increase the validity and

reability of the data.

Furthermore, the caffeine used may be an overdose for the Daphnia despite using

measured coffee powder, causing adverse effect on it rather than the desired effect. Using different

amount of caffeine on only one specific Daphnia and finding mean increase the datas validity and

reability.

Extra care was taken when activity of reading data was taken place. Since overlapping of

points marked by observer may affect the validity of data, thus when the observer start to plot the

marks on the paper, another person or the reader of data start counting the sound of the pencil

hitting the paper. This will, for sure, give arise to two readings afterwards and most likely to happen

result is chosen .This ensures the heart beat of Daphnia in both distilled water and caffeine solution

to be continuous and logical ,guarantee the validity and reability of data.

Using pond water / Daphnia culture solution, in this case , using pond water for the Daphnia

to be cultured before the experiment starts also increases the reability of data. Since the pond water

is the suitable surrounding for Daphnia, thus its heart beat will be in normal rate and culturing the

Daphnia in either distilled water and caffeine solution will show the perfect differences leading to

increasing in validity and reability of data.


15/17

Risk Assessment

Safety precaution

In order to avoid any accident or injury during the experiment in laboratory, the

precautionary steps should be taken and applied. Wearing lab coat and a pair of suitable shoes are

compulsory when conducting an experiment in the lab at all times to protect the skin and clothing

from spillage of any chemical substance. Furthermore, the glassware such as beakers and boiling

tubes should be handled with full care because they are fragile. The microscopes used are very fragile

and the light bulbs can get hot, precautionary steps should taken. For the Daphnia, make sure to be

careful, not to feed too much caffeine to the Daphnia only a maximum of 1% as we may not be able

to get reading due to it dying. The concentration of the solution is controlled so that the Daphnia

wont be affected.

Ethical issue

To determine the effects of a human life, we have to take a substitute of a human being and

then infer that any result that we obtain from this experiment will be the same as what will happen

in a human. Obviously we have to take into count that the amount of caffeine consumption of the

Daphnia and that of human will be different as the scales as to how big we are different. We hve to

be careful not to feed too much caffeine to the Daphnia only a maximum of 1% as we may not be

able to get a reading due to it dying.Daphnia are a great model for this experiment because they can

be easily handled and manipulated. Daphnia are also visible under the microscope and it is easier to

see their heart beat. Daphnia are advantageous when it comes to experiments because they are easy

to keep and maintain, they are also easy to study plus they are inexpensive. But, humans cant be

compared to daphnia due to their difference in the central nervous system. It should also be

assumed that daphnia are small and the caffeine concentration that increased the daphnia heart rate

to max will not increase the heart rate of the human. Another important fact is that, daphnia have a

neurogenic heart meaning it doesnt contract but instead conducts impulses versus human hearts;

they are myogenic meaning they contract. Although the Daphnia are simple organisms that may not

suffer in the same way as higher animal, they still deserve respect. These Daphnia should be returned

promptly to the holding tank after being examined.


16/17

Further Investigation

A similar experiment can be carried out to investigate the relationship between number of Daphnias

heart beat and alcohol concentration. This investigation is run to see the effect of varying amount of

alcohol concentration on Daphnias heart beat. Since the alcohol is known as depressant , two valid

hypothesis can be made.

First of all, in the presence of alcohol, the number of heart beat of Daphnia may decrease.

And for the second hypothesis, as the amount of alcohol increases, the number of heart beat will

decrease. The procedure for this experiment is the same with above and all we need to do is

substituting the caffeine concentration with alcohol amount or concentration of 10%. 20%, 30%, 40%

and 50%. Control should be taken with distilled water or better in pond water solution to get the real

number of heart beat.

There should be a decrease in number of heart beta for 15 seconds for 10 minutes as alcohol

introduced because of the depressant property of alcohol, slowing ddown the number of heart beat.

Conclusion

In conclusion, as the caffeine increased, the daphnias heart rates also increased and the hypothesis

is accepted. Through the labs results it is believed that thereis a relationship between the daphnias

and humans heart rate therefore if an increase in the daphnias heart rate is due to high caffeine

concentration, then humans also have a high heart rate after consumption of caffeine. This is

dangerous as mentioned before because this makes human prone to numerous diseases in the body

that correlate with caffeine. First of all, increase in heart rate means that blood is being pumped in

the human body at a higher rate which increases the chance of damaged or erupted veins and

arteries which further will increases the humans chance of getting atherosclerosis.


17/17

Reference

1. http://en.wikipedia.org/wiki/Daphnia2. http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&

bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa

=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm

=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffei

ne&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=68

1

3. http://en.wikipedia.org/wiki/Caffeine
http://en.wikipedia.org/wiki/Daphniahttp://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://en.wikipedia.org/wiki/Caffeinehttp://en.wikipedia.org/wiki/Caffeinehttp://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://www.google.com.my/search?q=daphnia+culture&hl=en&safe=off&biw=1366&bih=681&prmd=imvnsfd&source=lnms&tbm=isch&ei=j8ijTqWxKoXorQeWkrH9Dw&sa=X&oi=mode_link&ct=mode&cd=2&sqi=2&ved=0CA8Q_AUoAQ#hl=en&safe=off&tbm=isch&sa=X&ei=msijTqjLFcjlrAf0zNzhAQ&ved=0CDoQvwUoAQ&q=daphnia+and+caffeine&spell=1&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=efa7cf78339474ac&biw=1366&bih=681http://en.wikipedia.org/wiki/Daphnia

Documents

effect of caffeine on body.pdf