Transport in Plants | OCR A-Level Biology A (H420)
Transport in Plants
- 56 questions
- 5 subtopics
- Module 3: Exchange and transport
- Component 01 and Component 03
Transport in plants closes Module 3.
It covers xylem and phloem and how they are arranged in root, stem and leaf, transpiration and the potometer, the pathways water takes from soil to leaf, the adaptations of xerophytes and hydrophytes, and translocation from source to sink.
Sample questions from Transport in Plants
Answer each one closed book first, then open the answer.
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Xylem, phloem and vascular tissue
Why can water flow uninterrupted through xylem vessels?
Show the answer
Xylem vessels have no end walls between adjacent cells, forming continuous tubes. -
Xylem, phloem and vascular tissue
In a herbaceous dicotyledonous leaf, where is the xylem positioned relative to the phloem within the veins?
Show the answer
Xylem is on the upper side and phloem is on the lower side. -
Transpiration and the potometer
Explain how higher temperature increases transpiration rate.
Show the answer
Higher temperature increases the kinetic energy of water molecules and decreases relative humidity of surrounding air. -
Transpiration and the potometer
Why must the shoot be cut underwater when setting up a potometer?
Show the answer
To prevent air entering the xylem and blocking water flow. -
Water uptake and movement up the xylem
What is the function of the Casparian strip in the endodermis?
Show the answer
It blocks the apoplast pathway, forcing water to enter the symplast to reach the xylem. -
Water uptake and movement up the xylem
What is adhesion and what role does it play in xylem transport?
Show the answer
Adhesion is the attraction between water molecules and the hydrophilic walls of xylem vessels, helping to support the water column. -
Xerophytes and hydrophytes
How does the leaf structure of marram grass reduce transpiration?
Show the answer
Marram grass has rolled leaves with stomata on the inner surface, creating a humid microenvironment that reduces transpiration. -
Xerophytes and hydrophytes
Why do water lilies have stomata only on the upper leaf surface?
Show the answer
Because the lower surface is in contact with water.
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Xylem, phloem and vascular tissue | Xylem vessels and lignin, sieve tube elements, sieve plates and companion cells, and how the two tissues are arranged in root, stem and leaf. | 17 |
| Transpiration and the potometer | Why transpiration follows from gas exchange, how light, temperature, humidity and wind change the rate, and what a potometer actually measures. | 10 |
| Water uptake and movement up the xylem | The apoplast and symplast pathways, the Casparian strip, and how cohesion, adhesion and the transpiration stream pull water to the leaf. | 10 |
| Xerophytes and hydrophytes | The adaptations that cut water loss in cacti and marram grass, and the air spaces, surface stomata and reduced xylem of a water lily. | 9 |
| Translocation | Source and sink, the active loading of sucrose into companion cells and sieve tubes, and the water potential gradient that drives mass flow. | 10 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby sections
OCR A-Level Biology A Active Recall Guide
Every section, not just this one. 1,833 questions with their answers.