Transport systems in plants
Plants need for a transport system must be clearly understood by GCSE Biology students. The fact that plants have in effect two different transport systems needs to be explained in terms of how the structure of xylem and phloem are adapted to their functions. Students need to be able to explain how water and mineral ions are taken up by plants, relating the structure of root hairs to their function. Both the processes of translocation and transpiration need to be described; this includes the structure and function of stomata. GCSE Biology students need to be able to explain the effect of a variety of environmental factors on the rate of water uptake by a plant, including light intensity, air movement and temperature.
When delivering this topic, it is important to remind students that plants are multicellular organisms, just like animals and as such that they contain differentiated cells, tissues and organs. Students often display confusion that plants contain tissues and organs and when asked to name a particular tissue in a plant and it's function they are unable to do so or when asked to name a tissue they state an organ (for example root).
Another common misconception is that the only way that water is used by plants is for transpiration, when delivering this topic make sure to stress that water is also used to maintain structure and in cellular processes.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Plant Transport *suitable for home teaching*
This film, from Twig World, explores how plants transport resources via the xylem and phloem. The key points made in the film are:
- Transpiration is the evaporation of water from leaves into the atmosphere.
- It causes water to be sucked up from roots to the leaves.
- Water enters the roots from the soil by osmosis.
- The xylem and phloem are systems of hollow tubes that carry the water and food.
Students could watch this video in pairs and then be asked to identify these four key points, either from scratch or provided with a gapped handout.
SAPS protocol for investigation transpiration
In this classic experiment the rate of water uptake by a shoot, due to transpiration is measured by using a simple but effective potometer. Once set up the potometer can then be placed in different situations, changing one environmental factor at a time. This investigation would work well as a demonstration or could be set up by groups of GCSE Biology students with teacher/technician support
Animation on transport in plants from SAPS
This animation allows students to view the key processes of plant transport in xylem and phloem. The animation can be used in full screen, there is also a video version on YouTube or this can be downloaded. There are a set of teacher notes to accompany the animation.
Jheni Osman: Trees
In this short film scientist Jheni Osman describes how the transport systems in plants, the xylem and phloem, may limit the height to which trees can grow. The investigation consider that as Transpiration is driven by evaporation from the leaves, pulling water up through the xylem,the taller the tree, the further the water has to move against gravity. Students could be posed this question about tree height and transpiration as a starter activity question and then watch the video to confirm the findings.
