Neco 2024 Biology Question 5

Practice essay / theory question 5 from the 2024 Neco Biology examination. This question covers plant transport .

Neco 2024 Biology Essay / Theory
Topic: plant transport
Question 5 NECO • 2024 • BIOLOGY • essay

The diagram shows a mature dicotyledonous plant with the parts labelled as follows: A – root hairs, B – endodermis, C – xylem vessels, D – phloem sieve tubes, E – leaf blade, F – stomata, G – guard cells, H – transpiration stream. Using this diagram, answer the following questions.

Question Parts

( a )
Describe the complete pathway of water from the soil to the leaf, referring to the labelled parts in the diagram and explaining the role of each part in the movement of water.
( b )
Answer the following:
( ) Explain how the plant regulates water loss through stomata when ambient temperature is high.
( ) Predict the effect on the rate of transpiration if atmospheric humidity decreases, and justify your prediction.
( c )
A researcher measured the water potential in the root cortex as -0.2 MPa and in the leaf mesophyll as -0.8 MPa. Assuming steady flow, (i) calculate the magnitude of the water potential gradient and the equivalent height of a water column that would produce this gradient (use \rho = 1000 kg·m⁻³, g = 9.8 m·s⁻²). (ii) Discuss how this gradient supports the cohesion‑tension theory.
( ) Calculate the gradient and equivalent water‑column height.
( ) Discuss the relevance of this gradient to the cohesion‑tension theory.

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About This Question

This is Neco 2024 Biology Question 5. It is one of the essay questions from the 2024 Neco Biology examination.

The question covers plant transport .

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