Examples Of A Poor Lab Report Biology Essay

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Procambarus clarkia, also known as crayfish, belongs to a crustacean family that is called Decapoa. This order has 10,000 species. The different species are divided into two different superfamilies: Astacoidea and Parastacoidea. The Astacoidea, which contains families Astacidae and Cambaridae, occur in the Northern Hemisphere. The Parastacoidea, which contains family Parastacidae, inhabit the Southern Hemisphere. These families live in Europe, Australia, New Zealand, North and South America, and Asia.

Crayfish, which lack a water tight exoskeleton and have gills, establish colonies in aquatic, semi-aquatic, and high humidity areas. Roughly 10 percent of crayfish are of the fresh water species. These crayfish are omnivores, meaning they feed mainly on aquatic vegetation, other invertebrates, and particles of decomposing plant and animals. They are very susceptible to predators during their adolescent and post molting state of their life.

Crayfish are classified as ectotherms. Ectotherms are defined as "any so-called cold-blooded animal; that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface" (Encyclopedia Britannica). "The body temperatures of aquatic ectotherms are usually very close to those of the water. Ectotherms do not require as much food as warm-blooded animals (endotherms) of the same size, but most cannot deal as well with cold surroundings."

Crayfish are good subjects for studies on aspects of "innervation including identifying neuromuscular junctions and their differences, axon types, muscle types, neurotransmitters, behavior, and long term modification of nerve and muscle types" (Stock, Todd). In this case, the crayfish were used to measure CHH (crustacean hyperglycemic hormone). This hormone is released under times of stress and is transferred to the hemolymph (circulatory fluid). This hormone is present at the end of the eyestalk, in an organ called the "x-organ", of crustaceans. The x-organ is a group of neurosecretory cells. This hormone is the more frequently seen hormone in the eyestalk of the crayfish. The main role of this hormone is to maintain the glucose levels in the hemolymph. A similar hormone, called glucagon, maintains the normal glucose levels in the blood of humans. This hormone has the opposite effect of insulin, meaning it increases the glucose levels in the blood.

In this lab, measurements of CHH are being taken from two different crayfish, one with eyes and one without. My null hypothesis is that there will be no change in the glucose levels between these two specimens. My working hypothesis is that there will be a higher glucose level in the sample taken from the crayfish with eyes.

Methods and Materials

In this lab, we used two different types of crayfish (Carolina Biological Supply Burlington, NC), one with eyes and one without eyes (the eyes had been previously removed by instructor). All together, with 2009 and 2010 data, there were a total of twelve pairs of crayfish. The pairs of crayfish were match in size. This was so you didn't have one small crayfish and one that was very large. Chloroform was used to put the crayfish under stress. Ringer's solution (Department of Biology and Environmental Science), which is made of 12g NaCl, 0.4g KCl, 1.5g CaCl2, 0.5g MgCl2, 0.17g NaHCO3 into 700 ml water, was put into the crayfish after removing some hemolymph. This solution substituted for the amount of hemolymph taken from the crayfish. Regular syringes were used to retrieve the samples. A Spectronic 20 Plus was used to measure the absorbance levels.

With each crayfish, we held it from behind, on each side of the cephalothorax. We then held the tail down while someone else inserted a syringe and drew out ~0.1 mL of hemolymph. Immediately after the hemolymph was taken, ~0.1 mL of Ringer's solution was inserted into the crayfish. The hemolymph sample was then placed into a small test tube. This was done to each crayfish before stress. After taking the first sample of hemolymph, the crayfish were put in water to rest for about 15 minutes. Then, they were placed under stress in a small tub of chloroform for 20 seconds. They were then able to rest in the water for 15 more minutes. After they rested for 15 minutes, we took another sample of hemolymph and replaced it with Ringer's solution. After all of our samples were taken and put into small test tubes, we made a blank (~0.1 mL Ringer's solution and ~1.5 mL enzyme solution) and a glucose standard (~0.1 mL glucose, ~0.1 mL Ringer's solution, and ~1.5 mL enzyme solution). To each of the tubes of hemolymph, we added ~1.5 mL enzyme solution (Department of Biology and Environmental Science). We them placed the tubes in a water bath of 37° C for 30 minutes. After the tubes were taken out of the water bath, we placed the contents of each tube in a separate cuvette. The cuvettes were then placed in the Spectronic 20 individually for measuring the absorbance of the samples. After these measurements were taken, the glucose concentration was calculated for each sample.

Results

2010 Data

Before Stress

After Stress

Before Stress

After Stress

Std.

Hemo.

Std.

Hemo.

Glucose Concentration

Pair 1

With eyes

0.34

0.11

0.34

0.26

0.0162

0.0382

Without eyes

0.34

0.06

0.34

0.03

0.0088

0.0044

Pair 2

With eyes

0.24

0.04

0.23

0.05

0.0083

0.0108

Without eyes

0.24

0

0.24

0

0

0

Pair 3

With eyes

0.26

0.18

0.26

0.33

0.0346

0.0635

Without eyes

0.26

0.04

0.26

0.02

0.0077

0.0038

Pair 4

With eyes

0.35

0.235

0.35

0.425

0.0336

0.0607

Without eyes

0.35

0.125

0.35

0.115

0.0179

0.0164

Pair 5

With eyes

0.43

0.42

0.43

0.41

0.0488

0.0477

Without eyes

0.43

0

0.43

0.015

0

0.0174

2009 Data

Before Stress

After Stress

Std.

Hemo.

Std.

Hemo.

Pair 1

With eyes

0.06

0.06

0.06

0.03

Without eyes

0.06

0.17

0.06

0.05

Pair 2

With eyes

0.2

0.25

0.2

0.45

Without eyes

0.2

0.49

0.2

0.34

Pair 3

With eyes

0.11

0.02

0.11

0.24

Without eyes

0.11

0.09

0.11

0.04

Pair 4

With eyes

0.155

0.12

0.155

0.42

Without eyes

0.155

0.79

0.155

0.4

Pair 5

With eyes

0.06

0.025

0.06

0.07

Without eyes

0.06

0.015

0.06

0.02

Pair 6

With eyes

0.28

0.18

0.28

0.23

Without eyes

0.28

0.33

0.28

0.22

Pair 7

With eyes

0.15

0.12

0.15

0.23

Without eyes

0.15

0.06

0.15

0.05

When calculating the glucose, it appears that the crayfish that still had eyes had a higher concentration of glucose in their hemolymph than the crayfish without eyes. In each pair, the glucose levels were higher in the crayfish with eyes. The levels were even higher after the crayfish had been under stress rather than before stress with the crayfish that had eyes. The levels seemed to be higher before stress with the crayfish that did not have eyes. Refer to the tables above.

Based on the working hypothesis the data supports it. The blood concentration of glucose increased dramatically in the crayfish with eyes that were exposed to stress. The blood glucose of crayfish without eyes increased slightly or not at all.

Discussion

With the results that the class calculated, my hypothesis was supported. I hypothesized that the crayfish with eyes would have a higher glucose level than those that did not have eyes. Things that could have gone wrong would be the timing, retrieving the hemolymph, and making the solutions. We may have left the crayfish in the chloroform for too long or not long enough. The crayfish could have been at rest for a longer amount of time after being under stress which could have caused a change in their glucose levels. We could have put the needle in too far or not far enough. We could have gotten the measurements of the solutions wrong, either too little or too much of a certain ingredient. To make the experiment better, we could have reduced the stress from outside sources, such as poking the crayfish or bothering them in general. We could have had more replicates to get more measurements from. We also could have had more controls. We could have taken a sample before we removed the eyes from the crayfish and maybe tried to give the hormone back through injection. Overall the experiment was a success.

Literature Cited

"ectotherm." Encyclopædia Britannica. 2010. Encyclopædia Britannica Online. 05 Oct. 2010 <http://www.britannica.com/EBchecked/topic/1516418/ectotherm>.

Bowen, R. 1999. Glucagon. http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/glucagon.html

Stock, T. 1997. The Crayfish: background and related neurological research pertaining to Cheliped (Claw) research. http://www.biol.sc.edu/~vogt/courses/neuro/notes/crawfish-claw-todd2.pdf

http://www.ncbi.nlm.nih.gov/pubmed/18281112

Laboratory Manual for Introduction to Physiology

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Example of a great lab report:

Effects of the hyperglycemic hormone on regulation of the hemolymph glucose concentration in response to stress in Procambarus clarkii

Introduction

Procambarus clarkii (crayfish) are organisms that thrive in the freshwater swamp regions of North America; generally in the regions of the south-central United States and northeastern Mexico (Rogers, 2000). Crayfish are excellent model organisms to conduct research on because of the location of the x-organ sinus at the base of the eyestalks. The crustacean hyperglycemic hormone (cHH) is a peptide that is produced and stored in the x-organs (Fanjul-Moles, 2005). This area also houses neurosecretory cells that release the cHH. These cells cause the hepatopancreas to release more glucose into the hemolymph (Sullivan, 2009). For the purpose of this study they are excellent organisms to experiment with due to the fact that the x-organs can be removed easily in order to see the effects with and without the hyperglycemic hormone when they are induced with stress. Any hormone that that raises blood glucose concentration is referred to as a hyperglycemic hormone (Saladin, 2010). In decapod crustaceans, hyperglycemia as a response to various kinds of stress has been observed. The crustacean hyperglycemic hormone is the regulator of the hemolymph glucose concentration in the crayfish when it is released from its storage facility in the x-organ complex. The cHH is a contributing factor for maintaining the homeostatic properties to ensure survival of the crustacean. (Chang, 2005).

The purpose for conducting this experiment was to show the correlation between the presence of the hyperglycemic hormone and the amount of hemolymph glucose concentration produced in crayfish. This study involved the application of stress to determine how the hyperglycemic hormone regulates the amount of hemolymph glucose produced in a crayfish with and without eyestalks. Crayfish from which the eyestalks have been removed lack x-organs and sinus glands and so they will not be able to produce or release the hyperglycemic hormone (Sullivan, 2009). The working hypothesis of this experiment stated Procambarus clarkii with intact x-organs exhibit higher hemolymph glucose levels then Procambarus clarkii without x-organs under stress conditions. The corresponding null hypothesis stated that there would be no difference between the experimental and control groups of Procambarus clarkii under stress conditions.

Methods

The following methods were modified from the Laborartoy Manual for Intorduction to Physiology (Sullivan, 2009). Five test tubes were obtained and each one was filled with 0.1mL of crayfish Ringer's and 3.0mL of the combined enzyme-color reagent solution. (This solution included glucose oxidase, peroxidase, and 3-3' dimethoxybenzidine). The control test tube contained 0.1mL glucose standard (with a concentration of 5mg/100mL) in addition to the previous four test tubes. Then, to a cuvette 800 - 1,000µL of crayfish Ringer's solution were added. Two Procambarus clarkii (crayfish) were retrieved; one with eyestalks and one without the eyestalks (removed prior to lab). Approximately 0.1mL of hemolyph glucose was obtained from each of the crayfish at the base of the last walking leg using a 1cc (cubic centimeter) syringe. The collected hemolymph was immediately placed into the designated test tube and was incubated for approximately 30 minutes at 37˚C. Next, while waiting for the test tubes to incubate, approximately 0.1mL of crayfish of Crayfish ringer's was injected into the crayfish. Once injected, the crayfish were given a 15 minute relaxation period. After incubation was complete, the cuvette containing crayfish Ringer's was placed in the Spectrophotometer - 20 from Bausch and Lomb to zero the machine. Approximately 800 - 1,000µL of the incubated solutions and the incubated control were distributed into cuvettes and the absorption was measured using a Spectrophotometer - 20 set 450nm wavelength. Note that after every absorption reading the Spectrophotometer - 20 was re-zeroed using the crayfish Ringer's blank.

Next, the two crayfish were placed in separate containers with about 500mL of 0.1% chloroform (stressful environment) for the same amount of time, which was approximately 20 seconds. They were then placed back into clean water and were allowed to rest for 15 minutes. Using the method previously mentioned, 0.1mL of hemolymph was obtained from the "stressed" crayfish. Immediately after, these samples were then placed into the appropriate test tubes and incubated for approximately 30 minutes at 37˚C. Once incubation was finished 800 - 1,000µL were placed into cuvettes and the absorption was determined using the same technique already mentioned. All supplies used in this experiment were provided by the Carolina Biological Supply Company.

Results

Table 1 shows the relationship between the hemolymph glucose concentration and the presence or absence of eyestalks (x-organs) before and after stress. The Procambarus clarkii (crayfish) with eyestalks (x-organs) exhibited an increase of hemolymph glucose concentration after stress. The crayfish without eyestalks (without x-organs) did not exhibit any observable pattern of hemolymph glucose concentration.

Table 1. Hemolymph glucose concentration in Procambarus clarkii with and without eyestalks before and after stress.

Hemolymph Glucose (mg/100mL)

Before Stress

After Stress

With eyestalks

Crayfish 1

5.000

2.500

Crayfish 2

6.250

11.250

Crayfish 3

0.909

10.909

Crayfish 4

3.871

13.548

Crayfish 5

2.083

5.833

Crayfish 6

3.214

4.107

Crayfish 7

4.000

7.667

Crayfish 8

0.238

1.214

Average

3.196

7.129

Without eyestalks

Crayfish 1

14.167

4.167

Crayfish 2

12.250

8.500

Crayfish 3

4.091

1.818

Crayfish 4

25. 484

12.903

Crayfish 5

1.250

1.667

Crayfish 6

5.893

3.929

Crayfish 7

2.000

1.667

Crayfish 8

0.476

3.801

Average

8.201

4.807

When considering the overall effects of CHH response on hemolymph glucose levels, the change of average hemolymph glucose concentration for crayfish with and without eyes was calculated as (average glucose concentration after stress - average glucose concentration before stress) for each treatment group. Results shown in Figure 1 reveal that the crayfish without eyes had a reduction in hemolymph glucose concentration, whereas the control crayfish with eyestalks intact had a significant increase in the hemolymph glucose concentration after stress (p=0.019).

Figure 1. Hemolymph glucose concentration of crayfish with and without eyestalks were sampled before and after exposure to stress (chloroform). Change in glucose concentration (mg/ml) represents the average glucose concentration after stress minus the average glucose concentration before stress for members of each treatment group. (p>0.05)

Discussion

Based on the data, the working hypothesis is failed to be rejected due to the fact that Procamburas clarkii (crayfish) without x-organs did not exhibit higher hemolymph glucose concentrations than crayfish that contain x-organs. The reason for this failed rejection was due to the fact that the results were significant, as shown in Figure 1. It is evident that the presence of the x-organ complex and the release of the crustacean hyperglycemic hormone increased the amount of glucose in the hemolymph after stress was induced. To further support this conclusion, the crayfish without the x-organ complex did not produce an observable pattern to show that hemolymph glucose concentration was increased after stress was applied.

The crustacean hyperglycemic hormone (cHH) is very important in maintaining homeostasis in the crayfish; therefore it is also a factor in how the animal behaves and changes in anatomy due to the absence of this hormone. The cHH is a contributor to the hormone family, including the molt-inhibiting hormone (MIH) and the gonad-inhibiting hormone (GIH), that regulate important physiological processes, such as growth, reproduction and molting. (Mettulio et al., 2004). This supports the observations made when the lab groups were choosing their crayfish. The animals that had their eyestalks removed were a different color and some were losing limbs. Since the cHH is also a contributing factor to the regulation of growth and molting, it appears logical that the crayfish would be affected physically as well as chemically if this hormone would not be present in the body. The induced stress that was put upon the animal without its x-organ complex and cHH caused the crayfish's homeostasis to not function properly and produced the end result of molting issues and glucose concentration issues.

A study conducted by a Taiwanese scientist, Chi-Ying Lee and his associates, was very similar to the experiment conducted in class. Similarly they were researching the effects of the cHH, however in a different manner. They were researching how the cHH was involved in 5-hydroxytryptamine (5-HT) induced hyperglycemia. They discovered that 5-HT enhanced the release of the cHH which in turn elicits hyperglycemic responses. Another finding from the paper concluded that this response is not possible when the eyestalks are inhibited. (Lee, et al., 2001). These scientists may have obtained different results, but it reinforces that when the x-organ complex is present the hemolymph glucose concentration increases when the animal is introduced to stimuli and when it is not present or inhibited, hyperglycemic responses are not achieved.

The data obtained for the crayfish without eyestalks was skewed and could have been this way for a number of reasons. The solutions could have been made incorrectly or not incubated for the appropriate amount of time. Another possible issue is the extraction of hemolymph from the crayfish. The amount could have been less than required and therefore could have caused the spectrophotometer to have registered incorrectly. A reason for this confusion could have originated in the lab directions themselves. The area involving the creation of the solutions to be tested was extremely unclear; to counteract this issue the lab could be evaluated and rewritten to ensure that clarity is present in all aspects of the lab. To address the issue of extracting too little hemolymph from the crayfish; a tutorial before lab to allow practice would be very beneficial and would create comfort for the students performing the task.

The working hypothesis for this experiment was not clearly stated and did not involve all the necessary information to reach a valid conclusion. This is because one should not have compared crayfish with eyestalks to those without eyestalks under stress. The comparison should have been between crayfish with eyestalks before and after stress, and then compare the crayfish without eyestalks before and after stress. When one compares this it is clear that those crayfish with eyestalks release the cHH under stress as seen by the higher numbers in Table 1. To account for this change the hypothesis should have been written to include all of the information listed above; this would ensure a complete hypothesis and solid foundation to build results upon.

The crustacean hyperglycemic hormone is crucial in crayfish and all crustaceans for that matter, to ensure homeostasis of body functions and the physical aspect of the body itself. Without the x-organ complex the cHH is not present and the animal cannot respond properly to stress (stimuli) that can cause potential harm and possible death. This study concludes that crayfish with intact x-organs can counteract the stress placed upon it by raising the hemolymph glucose concentration to maintain homeostasis to ensure survival, while crayfish that contain no x-organs cannot not secrete cHH and counteract the effects of stimuli.

Literature Cited

Chang, E. 2005. Stressed-Out Lobsters: Crustacean Hyperglycemic Hormone and Stress Proteins1(On-line). http://www.redorbit.com/news/health/152035/stressedout_lobsters _crustacean_hyperglycemic_hormone_and_stress_proteins1/index.html. Accessed 24 October, 2009.

Fanjul-Moles, M. 2005. Biochemical and functional aspects of crustacean hyperglycemic hormone in decapod crustaceans (On-line) 142(3): 390-400. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W89-4HYD9MT- 1&_user=925033&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_ searchStrId=1063538796&_rerunOrigin=google&_acct=C000048221&_version=1&_url Version =0&_userid=925033&md5=f0870e41f8f2d91cd5a42630b7bcfc72. Accessed 24 October, 2009.

Lee, C. P. Yang, H. Zou. 2001. Serotonergic regulation of crustacean hyperglycemic hormone secretion in the crayfish, Procamburas clarkii (On-line). http://www.jstor.org/pss/30158715. Accessed 25 October, 2009.

Mettulio, R., P. Edomi, E.A. Ferrero, S. Lorenzon, P.G. Giulianini. 2004. The crustacean hyperglycemic hormone precursors a and b of the Norway lobster differ in the preprohormone but not in the mature peptide. Peptides (On-line) 25(11). http://www.ncbi.nlm.nih.gov/pubmed/15501521. Accessed October 25, 2009.

Rogers, J. 2000. Procambarus clarkii (On-line), Animal Diversity Web. at http://animaldiversity.ummz.umich.edu/site/accounts /information/Procambarus_clarkii.html. Accessed October 25, 2009

Saladin, K.S., 2010. Anatomy and Physiology: The Unity of Form and Function. 5th ed. McGraw-Hill. New York, NY.

Sullivan, J.D. 2009. Laboratory Manual for Introduction to Physiology.

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