Transport of Sugar in Plants

What is translocation in plants?

The movement of sugars and other organic molecules through the plant.

What theory explains sugar transport in plants?

The source-to-sink theory.

What is a source in plant transport?

A region that produces or supplies sugar (e.g. leaves).

What is a sink in plant transport?

A region that uses or stores sugar (e.g. roots).

Why is a leaf considered a source?

It produces excess sugar via photosynthesis.

Why is a root considered a sink?

It uses or stores sugar and requires a supply from the source.

What is transported in phloem during translocation?

Sap (water + dissolved sugars).

What are vascular bundles?

Structures in plants that contain xylem and phloem.

What happens at the source during translocation?

Sugar is actively pumped into the phloem using energy.

What is the effect of sugar entering the phloem at the source?

It increases solute concentration in the phloem.

Why does water move into the phloem at the source?

By osmosis due to high sugar concentration.

What is the effect of water entering the phloem?

It increases pressure in the phloem.

How does sap move through the plant?

From high pressure at the source to lower pressure at the sink.

What happens at the sink?

Sugar is removed and used or stored, reducing concentration.

Why does sugar not simply diffuse back into the leaf?

Because it is actively transported and creates a pressure flow system.

What is phloem sap made of?

Water and dissolved sugars.

Why is pressure important in translocation?

It drives the mass flow of sap from source to sink.