Question

Arrange the following five events in a correct order that explains the mass flow of materials in the phloem.
1. Water diffuses into the sieve tube elements.
2. Leaf cells produce sugar by photosynthesis.
3. Solutes are actively transported into the sieve elements.
4. Sugar is transported from cell to cell in the leaf.
5. Sugar moves down the stem.

• A. 2 - 4 - 3 - 1 - 5
• B. 2 - 4 - 1 - 3 - 5
• C. 1 - 2 - 3 - 5 – 4
• D. 4 - 2 - 1 - 3 – 5

Answer 1

The correct option is A 2 - 4 - 3 - 1 - 5

Food is transported by the vascular tissue phloem from a source (part of the plant which synthesis the food, i.e., the leaf) to a sink (the part that needs or stores the food) in these steps:
I. Leaf cells produce sugar by photosynthesis.
II. Sugar is transported from cell to cell in the leaf.
III. Solutes are actively transported into the sieve elements.
IV. Water diffuses into the sieve tube elements.
V. Sugar moves down the stem.