CAIE A-Level Biology AS 7.2.7 Companion Cells Transfer Assimilates Questions

Explain how companion cells transfer assimilates into and out of sieve tubes using evidence from each question and mark scheme.

Exam points

Explain how companion cells transfer assimilates into and out of phloem sieve tubes.

[Maximum number: 1]

Carrier proteins in the cell surface membranes of companion cells are involved in the transfer of assimilates to phloem sieve tubes. The diagram represents the use of two types of carrier protein in this process.

Figure for Question CAIE A-Level Biology AS 7.2.7 Companion Cells Transfer Assimilates Questions question 1 — CAIE A-Level Biology AS

What are the substances labelled X and Y ?

$\mathrm{H}^{+}$ ions

sucrose

$\mathrm{H}^{+}$ ions

glucose

sucrose

$\mathrm{H}^{+}$ ions

glucose

$\mathrm{H}^{+}$ ions

All question bank results loaded

CAIE A-Level Biology AS 7.2.7 Companion Cells Transfer Assimilates Questions question 1