Answer:
Step-by-step explanation:
The transport system in flowering plants is primarily composed of two types of tubes: xylem and phloem.
1. Xylem:
Xylem is responsible for the transport of water and mineral nutrients from the roots to the rest of the plant, including the stems and leaves. It is a complex tissue consisting of several cell types. The main cells involved in water transport are the tracheids and vessel elements. These cells are dead and have specialized structures that facilitate the movement of water through the plant.
Water uptake by the roots occurs through osmosis, where water moves from the soil into the root cells, and then it is transported upwards through the xylem. This movement of water is driven by transpiration, which is the process of water loss from the plant's aerial parts (mainly leaves) in the form of water vapor. As water evaporates from the leaves, it creates a negative pressure or tension in the xylem, pulling more water up from the roots to replace what was lost.
2. Phloem:
Phloem is responsible for the transport of organic compounds, mainly sugars (such as sucrose), from the leaves (source) to other parts of the plant, such as roots, fruits, and developing tissues (sink). Unlike xylem, phloem contains living cells. The main cells involved in sugar transport are sieve tube elements and companion cells.
The movement of sugars through the phloem occurs through a process called translocation. Sugars are actively loaded into the sieve tube elements in the source (usually leaves) and then transported through the phloem to the sink tissues, where they are actively unloaded and used for growth, energy, or storage.
In summary, xylem is responsible for the transport of water and minerals from the roots to the rest of the plant, while phloem is responsible for the transport of organic compounds, mainly sugars, from the leaves to other plant parts. These two types of tubes work together to ensure the proper distribution of water, nutrients, and energy throughout the flowering plant.