Question 1

What is the role of phloem in plant transport?

Accepted Answer

In plant biology, the phloem is responsible for the transport of organic nutrients, particularly sucrose, from the leaves to other parts of the plant. This process, known as translocation, is crucial for distributing the energy produced during photosynthesis to growth sites and storage tissues.

Question 2

How does the process of translocation occur in the phloem?

Accepted Answer

Translocation in the phloem occurs through a process called pressure-flow mechanism. Sugars are actively transported into the phloem sieve tubes, causing water to enter by osmosis. This creates a pressure gradient that pushes the sap along the phloem to areas of lower pressure, where sugars are unloaded for use or storage.

Question 3

What is the difference between phloem and xylem transport?

Accepted Answer

Phloem transport involves the movement of organic nutrients like sugars from sources (e.g., leaves) to sinks (e.g., roots, fruits), while xylem transport primarily involves the movement of water and minerals from the roots to the rest of the plant. Phloem transport is bidirectional, whereas xylem transport is unidirectional.

Question 4

What are sieve tubes and companion cells in the phloem?

Accepted Answer

Sieve tubes are elongated cells in the phloem that facilitate the transport of nutrients. They are connected end-to-end, forming a continuous channel. Companion cells are closely associated with sieve tubes and assist in the loading and unloading of materials into the sieve tubes, playing a crucial role in the maintenance and function of the phloem.

Question 5

Why is the transport in the phloem considered an active process?

Accepted Answer

Transport in the phloem is considered an active process because it requires energy in the form of ATP to actively load sugars into the sieve tubes. This active loading creates the osmotic gradient necessary for water to enter the tubes, generating the pressure needed for the flow of sap throughout the plant.

Transport in the phloem of plants

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