Translocation in phloem Quiz
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5 questions, one answer each
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1. Which cell type supplies the ATP for loading sucrose into the phloem?
- A. Xylem vessel
- B. Companion cell
- C. Palisade cell
- D. Guard cell
2. What causes water to enter the sieve tube at the source?
- A. Sucrose lowers the water potential
- B. Transpiration pull
- C. Active transport of water
- D. Sucrose raises the water potential
3. A ring of bark and phloem is removed from a stem. What is seen above the ring?
- A. The stem shrinks
- B. The stem swells as sucrose builds up
- C. The leaves wilt at once
- D. The xylem is blocked
4. Radioactive ¹⁴C is found in the phloem but not the xylem after a leaf is supplied with ¹⁴CO₂. This shows that:
- A. Water moves in the phloem
- B. Organic compounds made in the leaf are transported in the phloem
- C. The xylem is dead
- D. Mass flow is proved
5. Which observation is evidence against the mass flow hypothesis?
- A. Sap exudes from a cut stylet
- B. Sucrose is more concentrated in leaves than roots
- C. Solutes move at different rates and in opposite directions
- D. Inhibitors reduce translocation