Igcse Model Questions Vol1 2020 Biology Question 5

Practice essay / theory question 5 from the 2020 Igcse Model Questions Vol1 Biology examination. This question covers Transport .

Igcse Model Questions Vol1 2020 Biology Essay / Theory

Topic: Transport

Question 5 IGCSE_MODEL_QUESTIONS_VOL1 • 2020 • BIOLOGY • essay

A researcher is studying the rate of water transport in the stem of a young bean plant. The plant is kept in a controlled environment at 25 °C. When the stem is placed in distilled water, the height of the water column in the stem rises from the cut end to a height of 12 cm after 30 minutes. When the same stem is placed in a solution containing 0.5 mol dm⁻³ sucrose, the height after the same period is only 8 cm.

Question Parts

( a )

Explain why the height of the water column is lower in the sucrose solution than in distilled water.

( b )

Assuming the rate of water rise is constant during the 30‑minute period, calculate the percentage reduction in the rate of water transport caused by the sucrose solution.

( c )

The researcher now adds a hormone auxin that is known to increase the permeability of the xylem vessels by 20 %. Predict qualitatively how the height of the water column after 30 min in the sucrose solution would change, and justify your answer.

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About This Question

This is Igcse Model Questions Vol1 2020 Biology Question 5. It is one of the essay questions from the 2020 Igcse Model Questions Vol1 Biology examination.

The question covers Transport .

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