The most amazing thing about trees

It can be a challenge for students to use ideas from physics and chemistry to explain biological concepts, and so here we explore two modelling activities which provide opportunities for students to do this.

Giant Redwoods can grow to 100m tall and they have to be able to move the water that they absorb through their roots up through the tree to the very top.

How do they do it? Although only suitable for older students, this fascinating video from Veritasium shows some well-known YouTube scientists being asked to solve the ‘mystery’: The most amazing thing about trees

The most widely accepted model for the movement of water in the Xylem is the cohesion-tension model. In this model, water is pulled up the xylem in the transpiration stream, from the bottom to the top of the plant. The water is drawn up by the tension created by evaporating water in the leaves, and cohesion between water molecules.

The topic of water transport in plants can be used to address important scientific ideas in biology, chemistry and physics. Have a look at this investigation of capillary action and an investigation to explore the properties of xylem tissue, where students model the movement of water in trees using straws.

Discuss

These two investigations use models to represent the structures and processes involved in water transport up the xylem.

What are the advantages and disadvantages of using modelling activities like these to investigate biological concepts?

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Teaching Biology: Inspiring Students with Plant Science

National STEM Learning Centre