Biology 9700 · AS & A Level · Movement into and out of cells

Movement into and out of cells — practice question

When sucrose is loaded into the phloem, it must first move out of mesophyll cells, then into a companion cell, before reaching the phloem. In many plants, proton pumps and co-transporter molecules help to carry out this process. Which row indicates the relative concentrations of sucrose in each type of cell?

  • Amesophyll cell 5, companion cell 10, phloem sieve tube element 15
  • Bmesophyll cell 5, companion cell 15, phloem sieve tube element 10
  • Cmesophyll cell 15, companion cell 10, phloem sieve tube element 5
  • Dmesophyll cell 15, companion cell 5, phloem sieve tube element 10

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