TRANSPIRATION LAB – whole plant methodAP Biology

PRE-LABis due Friday, October 16, 2015 (see attached) and official lab reports are due next Friday.

SETTING UP YOUR LAB REPORT

  • BACKGROUND (in paragraph form)
  • Why biogeochemical cycles (such as the water cycle) are important to organisms.
  • Transpiration – definition, role in the water cycle, how it can occur (relate it to the properties of water…capillary action, adhesion, cohesion, etc.), water potential.
  • Describe the anatomy of a plant (stomata, guard cells, parenchyma cells, schlerenchyma cells, collenchyma cells, mesophyll layer, three types of tissue found in plants: x ylem, phloem, epidermal and how they relate to transpiration.

  • Describe the path of water up through a plant from the soil.
  • Discuss environmental factors that can affect transpiration.
  • Describe the type of plant used in the experiment: scientific name (Genus species), description, habitat, etc.
  • PURPOSE OF LAB (see teacher website…under AP Bio: Biochemistry link.)
  • HYPOTHESIS: predict in IF/THEN form the results of the experiment after subjecting plants to different environmental factors: humidity, dark, heat, wind, control.
  • MATERIALS: list the materials used in bullet-form
  • PROCEDURES: list (and number) the steps of your experiment for the WHOLE-PLANT METHOD and LEAF SURFACE AREA CALCULATIONS (there are two ways you can do this last part. You and your group can choose).
  • DATA:
  • transpiration data table for five days for each environment (see below)
  • rate of transpiration graph (line graph of cumulative percent change in mass per time in days)
  • leaf surface area for each plant used in data table (can only do this on Friday after transpiration rates are obtained)
  • overall rate of water loss (change in y over change in x)per minute for each of the environmental conditions – put in data table (% change in mass/minute)
  • transpiration rate/surface area for each plant (% change in mass/minute/cm2)
  • CONCLUSION
  • Discuss the different variables: independent and dependent and any constants in this experiment.
  • Discuss your results: overall rate of water loss for each condition and transpiration rate/surface area for each condition.
  • Explain WHY each of the environmental conditions caused an increase or decrease in transpiration compared with the control.
  • Describe several adaptations that enable plants to reduce water from their leaves (C3, C4, and CAM plants, closed stomata during water shortages, why stomata are located on undersides of leaf usually, etc.)