Transpiration and stomatal control
BiologyPlant PhysiologyAges 16–17Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Plant Physiology
Adjust light, air humidity, wind and soil moisture, then watch the stomata open or close, the transpiration rate change, and water flow up the xylem. The simulation shows the plant's constant trade-off: opening stomata lets in CO₂ but loses water, while water shortage forces them shut and photosynthesis drops. A second screen runs the cobalt chloride paper practical: time how fast papers on the upper and lower surfaces of six kinds of leaf turn pink and relate it to the number of stomata on each surface.
Lesson: Water and mineral transport in plants
What it shows
Plants lose most of their water as vapour through stomata, pores bordered by guard cells. This transpiration pulls water up the xylem from the roots and cools the leaf. Its rate depends on stomatal opening and on the water-vapour gradient between leaf and air, so it rises in bright light, dry air and wind; when the soil dries out, the hormone ABA closes the stomata and photosynthesis drops. The Cobalt chloride paper screen runs the classic practical: papers on the upper and lower leaf surfaces turn from blue to pink, faster where there are more stomata.
How to use
Change one factor at a time with the Light, Humidity, Wind and Soil sliders and watch the stoma, the transpiration rate and the water balance; Blazing noon and Night compare two extremes. On the Cobalt chloride paper tab, choose a Leaf and the light, press Clip papers and read in the table how long each paper takes to turn pink. Compare dicot, monocot and floating leaves with their stomata counts.
Parameters you can change
- Light intensity 0–100 %
- Air humidity 10–100 %
- Wind speed 0–8 m/s
- Soil moisture 5–100 %
- Starting screen Factors, Cobalt chloride paper
- Leaf for the cobalt chloride paper test Bean (dicot), Sunflower (dicot), Apple (dicot tree), Maize (monocot), Oat (monocot), Water lily (floating leaf)
Questions to explore
- What happens to stomatal opening and photosynthesis when the soil is dry, even in bright light?
- Why can the water balance turn negative on a hot, dry, windy day even when the soil is moist?
- Why does the lower-surface paper turn pink first on a bean leaf but last on a water lily leaf?
Teaching ideas
All guides- How to Design an Inquiry-Based Lesson with SimulationsDesign an inquiry-based lesson with simulations: choose the inquiry level, plan the steps and scaffolds, and run a full guided lesson on transpiration.
- Transpiration Virtual Lab: Light, Humidity, Wind and WaterA transpiration virtual lab for the AP Biology investigation: change wind, light, humidity and soil water, measure the rate and explain it with stomata.
- Plant Transport Virtual Lab: Potometer, Xylem and PhloemA plant transport virtual lab: measure water uptake with a potometer at three temperatures, calculate the volume with πr²d and trace dye up the xylem of celery.
- Stomatal Density Virtual Lab: Count Stomata on a Leaf CastA stomatal density virtual lab: make a nail-varnish leaf cast, count stomata in fields of view, find density per mm² and compare upper and lower surfaces.
