Whole Plant Transpiration Lab AP Biology How to calculate transpiration RATE

STEP ONE: Calculating water loss g/day to ug/sec Steps for measuring water loss Calculate g of water/day lost then convert to ug/sec grams x 1 day x 1 hour x 1 minute = ___________ gram/sec day 24hr 60 min 60 sec Now convert your answer to ug/sec Hint: 1 g = 106 ug This answer is the amount of water lost 3. Calculate each day and write out your water LOSS in ug/sec for each day W ______ Th _________ Fr__________  Then do an average of all 3 days ______________ug/sec NOW to get the cm2

STEP TWO: Measuring Leaf Surface Area 1. Gently remove all the leaves on your plant and lay them on the grid to calculate the total number of cm2 HINT: You may trace around the leaves on the grid and then throw the leaf away. 1 cm x 1 cm grid to use: 4 boxes equal one square centimeter 2. Total the entire surface area in cm2. ________________ cm2 3. Now take your average water loss divide it by the cm2 to get your answer for the TRANSPIRATION RATE __________ug/sec/cm2

Leaf Surface Area Results Fan Plant = ______118_____ cm2 Control fan group ___172____ cm2 Dark Plant = ______136.75___ cm2 Control dark group __165.25_ cm2 Mist Plant = ___208_________ cm2 Control mist group __123.5___ cm2 Bright light plant = ___168____cm2 Control bright light group _157__cm2

RAW data for whole plant mass in grams Whole Plant Transpiration Mass in grams (g) Variable Day 1 Day 2 Day 3 Day 4 Fan 304.4 285.6 269.7 251.8 Dark 233.7 227.3 221.4 215.9 Mist 253.9 252.8 252.4 Bright Light 286.2 249.9 216.7 183 Control

Average Transpiration rate ug/sec/cm2 Calculate the transpiration rate for each variable and your control group Variable Average Transpiration rate ug/sec/cm2 Fan Dark Mist Bright Light Control