Lesson 3 ·Class 10 · Transpiration · Sort Lab
What Speeds Transpiration Up
Six factors, and the direction each one pushes.
Sort each condition by what it does to the rate of transpiration.
Sorted 0/10
All items sorted — check each bin.
VS
Free play — sort every item into the bin it belongs in; each correct drop tells you why. Switch to when you're ready to test yourself.
Most of these work through one of two things: whether the stomata are open, and how steep the water-vapour gradient is between the leaf and the air outside.
What this lesson covers
What you do
- Atmospheric pressure is the counter-intuitive one. Lower pressure means faster transpiration — which is part of why plants at high altitude face water stress.
Challenges to clear
- Sort every condition.
- Fill the 'Slows it down' column — the conditions that hold water in the leaf.
The task
Sort each condition by what it does to the rate of transpiration.
What this lesson covers
- Speeds it up: Bright sunlight (Stomata open in light, so more transpiration occurs during the day.); High temperature (Evaporation is faster, and warm air can hold more water than cold air.); Strong wind (Moist air is swept away from the leaf surface, so the air outside never becomes saturated.); A fall in atmospheric pressure (The rate increases as atmospheric pressure decreases.)
- Slows it down: A cloudy day (Stomata are only partially open, so loss is reduced.); Humid air (If the air outside is already moist, there is little gradient for water vapour to move down.); Still air (A saturated layer builds up around the leaf and stays there.); Carbon dioxide above the normal 0.03% (Raised CO₂ causes the stomata to close.); The plant is short of water and begins to wilt (The stomata close — a natural mechanism for conserving water.); A thick waxy cuticle (The greater the thickness of the cuticle, the less the evaporation.)
Hint
Most of these work through one of two things: whether the stomata are open, and how steep the water-vapour gradient is between the leaf and the air outside.