Effect of caffeine, nicotine, alcohol, epinephrine on Daphnia

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03 - 31 - 2006

RESULTS:

In this experiment the effect of different hormones on heart rate of _Daphnia_ was examined. It was investigated which substances act as stimulants and which substances act as depressant. Initially, _Daphnia_ was placed on depression slide under the microscope and the average heart rate was determined. Subsequently, _Daphnia_ was treated with different type of hormone and the effect on Daphnia heart rate was observed. It was investigated which substances act as stimulants and which substances act as depressant. Daphnia was treated with aged water, caffeine, ethyl alcohol, nicotine, and epinephrine, and their effect on heart rate of Daphnia was observed. The results are posted on table 1:

Table 1: Average heart rate for Daphnia at pre-stimulus and post stimulus for different hormones:

# OF TRY

AGED WATER

CAFFEINE

ETHYL ALCOHOL

NICOTINE

EPINEPHRINE

CONTROL

TREATED

CONTROL

TREATED

CONTROL

TREATED

CONTROL

TREATED

CONTROL

TREATED

1

277.2

278

285.2

343.2

297.2

266.8

318.5

274

298

344.8

2

204.68

200.67

189.3

272

228

171.3

270.67

238.67

298.67

324.67

3

273.3

289.3

232.7

262.7

234

222

244

126

252

295.3

4

264.67

194

269.33

324.67

258

167.33

262.67

272.67

258.67

184

5

360.3

283.4

283.7

310.4

279.1

235

274.1

339.6

283.6

252.2

6

204

260

272

328

328

228

244

160

276

340

7

285

324.7

285

335.3

283.3

299.3

282.7

270

276.7

299.3

8

264

259

279

300

295

296

299

294

N/A

N/A

AVERAGE

266.643

261.134

262.029

309.538

275.325

235.716

274.455

246.868

277.663

291.467

Standard

Deviation

49.337

44.373

34.068

29.426

33.734

50.310

25.687

70.690

17.857

56.964

P value

P>0.05

P0.05

P>0.05

P>0.05

During initial observation, Daphnia was placed in microscopic slide and the average heart rate was calculated. Then, aged water was added to Daphnia and its effect on heart rate of Daphnia was observed. The result is posted on table 1:

Figure 1: Age water added to Daphnia.

From figure 1 it can be observed that, originally Daphnia had an average heart rate of 266.644+/-49 beats per minute. When the daphnia was stimulated with aged water, the heart rate decreased to an average of 261.134+/-44 beats per minute. After performing Mann-Whitney U statistical test no significant difference was observed in the average heart of Daphnia before and after the addition of aged water.

Daphnia was then treated with caffeine and the change in heart rate was observed. The result is posted on figure 2.

Figure 2: Daphnia treated with caffeine

From figure 2 it can be seen that before the treatment, Daphnia had an average heart rate of 262.029+/-34 beats per minute. When solution containing caffeine was added to Daphnia, there was a significant change in heart rate of Daphnia. The Daphnia heart rate increased to an average of 309.534+/-29 beats per minute. After performing Mann-Whitney U statistical test, it was found that this increase in average heart rate of Daphnia was significant with p
From figure 3 it can be observed that there is a decrease in average heart rate of Daphnia when alcohol was added. Initially, Daphnia had an average heart rate of 275.325+/-33 beats per minute. After the addition of alcohol the heart rate of daphnia was decreased to an average heart rate of 235.716+/-50 beats per minute. After performing...
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