Question

How does phloem sap move in a plant?

Answer 1

The sap of the phloem tree runs through holes known as sieve tube plates. If the concentration of sucrose in the sink is lower than in the phloem, unloading occurs by diffusion; if the concentration of sucrose in the sink is higher than in the phloem, unloading occurs via active transport.

Complete answer:
Sucrose, amino acids, and organic acids are all found in phloem sap. Xylem sap contains water and minerals. Oligosaccharides and hormones are found all across the plant's body.

Sugars, hormones, and mineral components dissolved in water make up phloem sap. It flows from the point at which carbs are created or stored (the sugar source) to the point at which they are consumed (sugar sinks).

Translocation, or the transport of dissolved elements in a plant, transports sap through the phloem. Unlike xylem, which can only transport water upward, phloem may transport sap both uphill and downward, from sugar sources to sugar sinks:

Plant organs that produce sugars, such as leaves, are sugar sources. Sugar sinks are plant organs that consume or store sugars, such as roots, tubers (underground stems), and bulbs (swollen leaves).

The pressure-flow hypothesis is how scientists explain how translocation works in a plant's phloem.

The steps in this theory are :
- Osmosis allows water to enter the sieve tube elements.
- Water moves into the locations with the highest concentration of solutes during osmosis (in this case, sugars).
- Water inflow raises turgor pressure at the source, causing water and carbohydrates to flow through the sieve tube elements and into a sugar sink. (Turgor pressure is the force exerted by the fluid within the plant cell against the cell wall.)

Consider this procedure to be similar to turning on a garden hose-connected water faucet. Water from the tank pushes the water in front of it down the hose as it flows into it. Sugars are eliminated from cells at the sugar sink, resulting in low sugar content.

Turgor pressure develops as a sugar sink receives water and carbs. However, carbohydrates in the sink must be actively carried out of the sink and into required plant cells before it can become a sugar supply. As the carbohydrates are eliminated, water follows the solutes out of the cell and diffuses out, releasing the pressure.

Plants are pretty effective at spreading the richness of carbs and fluid to where the plant needs them since plant cells may operate as both sinks and sources, and phloem transport flows both uphill and downward. A plant can survive on its own as long as it has a constant supply of minerals, water, carbon dioxide, and light.

Note: When plants require sugar, sugar sinks that store carbs can become sugar sources. Because starch is a complex carbohydrate that is water-insoluble, it serves as a carbohydrate storage molecule. When a plant needs sugar, such as at night or during the winter when photosynthesis is less efficient, it can break down its starches into simple sugars, allowing a tissue that would otherwise be a sugar sink to become a sugar source.