Water transport in plants Quiz
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5 questions, one answer each
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1. Which statement about mature xylem vessels is correct?
- A. They are living cells with end walls
- B. They are dead cells with no end walls, forming hollow tubes
- C. They contain sieve plates
- D. They have thin walls with no lignin
2. What creates tension in the xylem?
- A. Active transport in the roots
- B. Pushing by root pressure
- C. Evaporation of water from the leaves
- D. Cell division in the stem
3. What is cohesion in the cohesion-tension theory?
- A. Attraction between water molecules and xylem walls
- B. Movement of water by active transport
- C. Evaporation of water from the leaves
- D. Attraction between water molecules due to hydrogen bonds
4. A potometer's capillary tube has an internal radius of 1.0 mm and the bubble moves 20 mm in 4 minutes. What is the rate of water uptake?
- A. 15.7 mm³ min⁻¹
- B. 5 mm³ min⁻¹
- C. 62.8 mm³ min⁻¹
- D. 78.5 mm³ min⁻¹
5. The trunk of a tree narrows slightly during the day. How does this support the cohesion-tension theory?
- A. It shows that the water is under tension, which pulls the xylem walls inwards
- B. It shows that roots push water up the trunk
- C. It shows that the xylem vessels are pumping water
- D. It shows that transpiration stops in the day