Transport in Plants
(IB Topic B3.2)
Essential Idea(s): Anatomical structures in living organisms are specifically adapted to optimize the movement of substances.
Unit Length: 2 Lessons (+1 AHL)
Guiding Questions
◊ What adaptations facilitate transport of fluids in animals and plants?
◊ What are the differences and similarities between transport in animals and plants?
| IB Statement(s) and Objective(s) |
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B3.2.7: Transport of water from roots to leaves during transpiration
B3.2.8: Adaptations of xylem vessels for transport of water
B3.2.9: Distribution of tissues in a transverse section of the stem of a dicotyledonous plant B3.2.10: Distribution of tissues in a transverse section of the root of a dicotyledonous plant
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Additional Higher Level Topics
B3.2.17: Generation of root pressure in xylem vessels by active transport of mineral ions
B3.2.18: Adaptations of phloem sieve tubes and companion cells for translocation of sap
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| Activities: ⓟ = podcast / ⍰ = inquiry 5 / ⓦ = Write it / Ӕ = The academy / Ⓡ = Read it |
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Lab ⓟ/ⓦ: Modeling Pressure Flow from Source to Sink (💁/👭 max 2) Get creative and think of a way to model pressure flow from the phloem source to sink. You could work with a group to do a role-play (people = sucrose?), or work solo to make a visual model (using paper and marbles as molecules?). The choice is up to you – just show us how pressure flow works in plants!
ⓡ (+NOS): Researcher affirms 86-year-old hypothesis (💁) A good hypothesis might float around science circles for decades – even centuries – before we have the technology and methods to gather evidence to support it. Such was the case with phloem — it took 86 years to validate the simple hypothesis for how nutrients and sugars move around plants. Along the way, some scientists went to great lengths to get the data needed to validate the hypothesis. Read through the articles and write a response, discussing: 1) What is the hypothesis that was validated?; 2) Why is it worth studying in the first place?; 3) How does nature use pressure gradients to move solutes around plants?; and 4) How might radioactive isotopes have been used in this experiment?
ⓦ “Inquiry 5″: Q&A on Transportation in Plants (💁/ 👭max 2) Create a list of 5 inquiry questions related to transportation in plants. Remember that good inquiry questions are conceptual / open-ended… SUCH AS: “How do plants use hydrostatic pressure to survive?” NOT: “What is the function of the companion cell?” If working solo, write out answers to your own questions; if working in pairs, record yourselves asking each other your 5 questions.
ⓟ/ⓦ How Trees Bend the Laws of Physics (💁/ 👭max 2) The giant sequoias in California are the tallest trees on earth – some reaching as high as 130 meters. This seems to defy a rule in physics: no straw can work beyond 10 meters high. If the xylem is just a natural form of straw, how do trees overcome this 10-meter limit? Watch this Veritasium video and answer: 1) How do xylem and transpiration work to move water up a plant?; 2) What is “negative pressure”? 3) Why is there a 10-meter limit to tubes moving water upward; and 4) How do plants overcome this limit? |