LabQuest
10
Transpiration
Water is transported in plants, from the roots to the leaves, following a decreasing water potential
gradient. Transpiration, or loss of water from the leaves, helps to create a lower osmotic potential in
the leaf. The resulting transpirational pull is responsible for the movement of water from the xylem
to the mesophyll cells into the air spaces in the leaves. The rate of evaporation of water from the air
spaces of the leaf to the outside air depends on the water potential gradient between the leaf and the
outside air.
Various environmental factors, including those conditions which directly influence the opening and
closing of the stomata, will affect a plant’s transpiration rate. This experiment will measure
transpiration rates under different conditions of light, humidity, temperature, and air movement. The
data will be collected by measuring pressure changes as the plant takes up water into the stem.
OBJECTIVES
In this experiment, you will
● Observe how transpiration relates to the overall process of water transport in plants.
● Use a handheld interface and a Gas Pressure Sensor to measure the rate of transpiration.
● Determine the effect of light intensity, humidity, wind, and temperature on the rate of
transpiration of a plant cutting.
Biology with Vernier 10 -
, LabQuest 10
Figure 1
MATERIALS
LabQuest metric ruler
LabQuest App masking tape
Vernier Gas Pressure Sensor plastic gallon size bag with twist tie
utility clamps heater, small electric
ring stand fan with slow speed
plant cuttings aerosol spray container or plant mister
plastic tubing clamps plastic syringe
dropper or Beral pipette graph paper or Logger Pro program
razor blade or scalpel
100 watt light source
PROCEDURE
Figure 2
10 - Biology with Vernier
10
Transpiration
Water is transported in plants, from the roots to the leaves, following a decreasing water potential
gradient. Transpiration, or loss of water from the leaves, helps to create a lower osmotic potential in
the leaf. The resulting transpirational pull is responsible for the movement of water from the xylem
to the mesophyll cells into the air spaces in the leaves. The rate of evaporation of water from the air
spaces of the leaf to the outside air depends on the water potential gradient between the leaf and the
outside air.
Various environmental factors, including those conditions which directly influence the opening and
closing of the stomata, will affect a plant’s transpiration rate. This experiment will measure
transpiration rates under different conditions of light, humidity, temperature, and air movement. The
data will be collected by measuring pressure changes as the plant takes up water into the stem.
OBJECTIVES
In this experiment, you will
● Observe how transpiration relates to the overall process of water transport in plants.
● Use a handheld interface and a Gas Pressure Sensor to measure the rate of transpiration.
● Determine the effect of light intensity, humidity, wind, and temperature on the rate of
transpiration of a plant cutting.
Biology with Vernier 10 -
, LabQuest 10
Figure 1
MATERIALS
LabQuest metric ruler
LabQuest App masking tape
Vernier Gas Pressure Sensor plastic gallon size bag with twist tie
utility clamps heater, small electric
ring stand fan with slow speed
plant cuttings aerosol spray container or plant mister
plastic tubing clamps plastic syringe
dropper or Beral pipette graph paper or Logger Pro program
razor blade or scalpel
100 watt light source
PROCEDURE
Figure 2
10 - Biology with Vernier
