What is the difference between a sieve tube and a duct?

Many people often confuse sieve tubes and ducts. The two have many similarities. For example, they are both professional terms in biological cytology and their names are also relatively similar. In fact, sieve tubes and ducts cannot be confused. For example, there are many ducts in industry, but these industrial ducts cannot be called sieve tubes. The following is a detailed introduction to the relevant professional knowledge of sieve tubes and ducts.

The difference between sieve tube and duct:

The ducts are dead cells

Sieve tubes are living cells

Vessels in the xylem are responsible for the one-way transport of water and salt from the roots upwards

Sieve tubes in the phloem are responsible for the bidirectional transport of organic matter from leaves to roots

The trachea is a long-distance transport system for water and inorganic salts composed of columnar cells in the xylem of vascular plants. The secondary wall thickness thickens unevenly, and the end wall is perforated or completely dissolved, thus forming a longitudinal continuous channel.

Sieve tubes are tubular structures in the phloem of angiosperms that transport organic nutrients. It is composed of a series of long cylindrical living cells whose end walls form sieve plates. Each component cell is called a sieve tube molecule.

Similarities: Both exist in plant cells, both function to transport substances, and both are tubular structures;

Differences:

Vessels are of vascular plants, while sieve tubes occur in angiosperms;

The trachea are composed of columnar cells (dead cells), and the sieve tubes are composed of a series of long cylindrical living cells connected by end walls forming sieve plates;

The trachea transport water and inorganic salts, while the sieve tubes transport organic nutrients.

Trachea is a dead cell with only cell walls~~ and the upper and lower cells are connected. It is located in the xylem of the vascular bundle. Its function is very simple, which is to transport water and inorganic salts absorbed from the roots to all parts of the plant body. The pipes for transporting water and inorganic salts in the xylem of the plant body are formed by many tubular cells with missing transverse walls connected up and down, and liquid can flow in the pipes. Roots, stems, and leaves all have trachea, and they are connected. Generally, they transport water, inorganic salts, and other substances dissolved in water from bottom to top.

Sieve tubes are located in the phloem of the vascular bundle. They are also arranged longitudinally, but the cells that make them up are alive. Each cell has a companion cell. The cell walls of the upper and lower cells are not connected, but the cell wall between them is specialized and suitable for the transportation of organic matter. Sieve tubes are used to transport synthesized organic matter to various places. The pipelines for transporting organic nutrients in the phloem of plants are composed of many tubular cells connected up and down. There are many small holes in the horizontal walls of adjacent cells above and below, which are called sieve holes. Roots, stems, and leaves all have sieve tubes, and they are connected. They can transport substances in both directions, generally mainly organic matter.

Simple memory:

1. Physiological activity: Sieve tubes are composed of living cells, and ducts are composed of dead cells.

2. Location: sieve tubes are located in the phloem, and vessels are located in the xylem.

3. Physiological function: Sieve tubes mainly transport organic matter, and trachea transport water and inorganic salts.