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Does caffeine affect heart rate?

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Does caffeine affect heart rate? Method * Use a pipette to transfer a daphnia to a cavity slide. Remove the water around the daphnia using filter paper. Add one or two drops of distilled water * Look at the daphnia through a microscope. Use a stopwatch to record the number of heartbeats per minute. Record the heart rate at intervals of two minutes over a 10-minute period. * Repeat the procedure using other daphnia in fresh slide and cover slips. Replace the water with caffeine solution. Repeat the procedure using several different concentrations of caffeine. Results WATER ONLY 1 DROP 2DROPS 3DROPS 4DROPS 5DROPS LOUISA 181/254/208 264/258/292 272/285/989 340/302/280 292/300/305 366/368/370 AVERAGE 214 271 515 307 299 368 BECKY 260/238/258 320/367/360 370/380/389 390 AVERAGE 252 349 389 390 ALEXIS 262/348/336 344/378/359 384/383 AVERAGE 315 360 384 GEMMA 180/188/196 208/216/196 268/260/250 280/292/304 AVERAGE 188 207 259 292 LAURA 248/200/244 272/244/280 288/260/240 AVERGE 264 265 263 VICKY 260/228/232 228/232/240 276/280/260 296/248/280 AVERAGE 240 233 272 275 Why does colour leak out of cooked beetroot? ...read more.


* Place 2cm3 of the dye solution into a colorimeter cuvette and take a reading for absorbency. Repeat the readings for all the temperatures. Results Temperature (degrees) Transmission (%) 5 60 10 53 20 50 30 43 40 30 50 30 60 23 70 16 Conclusion The higher the temperature the lower the transmission. The higher the temperature the more the beetroot leaks. This is because in, the plasma membrane, the pigments are moving randomly. If you doubled the temperature it would double the leakage. Do higher carbon dioxide levels lead to warmer conditions? Method * Set up the clamp stands, bosses and clamps so that each pop bottle is firmly held around the neck of the bottle. Position the clamp stands and bottles so that each bottle is the same distance from the lamp(s) - about 50cm or less if heat absorbers are used. * Unscrew the lid of one bottle and fill the bottle with carbon dioxide. ...read more.


Choose root tips which are white and have a firm, rounded end; tips that are turning brown will give you poor results. * Put the root tips in a watch glass containing approximately 2cm3 of acetic alcohol for a minimum of 10 minutes * Remove the root tips and place them in a second watch glass with approximately 5cm3 ice-cold water. Leave for 4-5 minutes, then dry the root tips on filter paper * Put the root tips into the pre-heated hydrochloric acid for exactly 5 minutes * Repeat step 3. Take care - root tips will be very fragile * Transfer one of the root tips to a clan microscope slide. Cut about 4-5mm from the growing tip. Make sure you keep the rounded tip; discard the rest * Gently break up the root tip cells with a mounted needle. Add one small drop of acetic orcein stain and leave to stain for two minutes * Cover with a cover slip, blot firmly with several layer of tissue or filter paper. Press gently to spread the root tip * View under the microscope and look for cells with chromosomes. Laura Chipperfield CORE PRACTICAL ...read more.

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