Researchers investigated the transport of water and mineral ions in birch trees (Betula pendula).
Describe how cohesive forces and adhesive forces between water molecules and xylem walls contribute to the transpiration stream.
A student setting up a potometer cut a leafy plant stem underwater before attaching it to the apparatus. Suggest why it is crucial to cut the stem underwater.
The water in the potometer contained a soluble fluorescent dye. Suggest how the student could determine whether this dye had traveled specifically through the xylem vessels of the cut stem.
During winter, de-icing salt (NaClNaClNaCl) is applied to roads. Run-off from these roads can significantly increase the ion concentration of the soil surrounding roadside birch trees. Explain why these trees often display severe leaf wilting in the spring, even when the soil is saturated with water.
A student hypothesised that treating the roots of healthy birch seedlings with a respiratory inhibitor that prevents ATP synthesis would lead to a similar wilting effect. Explain whether the student's hypothesis is correct.
Explain why birch saplings growing in high light intensity require more water than saplings growing in the shade, even when the ambient temperature and humidity are identical.
