Question

What do xylem vessels carry?

Answer 1

Hint: There are two types of tissues- meristematic tissues and permanent tissues. Xylem is the complex permanent tissue. That has four kinds of elements constituting a xylem tissue, these are tracheids, vessels, xylem fibers, and xylem parenchyma.

Step by step answer:Groups of cells whose origin are common and which perform a common function are called tissues. All plants have two types of tissues that are meristematic and permanent tissues.
Meristematic tissues are the tissues with constantly dividing cells and which usually occur in the specialized regions of active cell division. Permanent tissues are the tissues whose cells do not divide further. There are two types of permanent tissues that are simple tissues and complex tissues. Simple tissues are the tissues in which all cells are of the same kind whereas complex tissues are made up of more than one type of cells and they work together as a unit. Xylem is the complex permanent tissue that acts as a conducting tissue for water and minerals from roots to the stem and leaves. Xylem also helps to provide mechanical strength to the plant parts. Along with xylem, simple tissues like collenchyma and sclerenchyma also provide mechanical strength to the plant body. There are four kinds of elements constituting a xylem tissue, these are tracheids, vessels, xylem fibers, and xylem parenchyma.
Tracheids are thickly walled and lignified walled elements with the tapering end. These are elongated or tube-like cells Tracheids lack protoplasm and hence they are dead just like sclerenchyma simple tissue.
Many cells called vessel members constitute a single vessel which is a long cylindrical tube-like structure. Along with tracheids, the vessels form the main water transporting element. Vessels also lack protoplasm, they also have lignified walls and a large central cavity.
The main function of xylem parenchyma is the storage of food. Their cells are living and thin-walled. Their walls are made up of cellulose. The food materials stored by xylem parenchyma is in the form of fat or starch and other substances like tannins.
Xylem is of two types: primary xylem and secondary xylem. Primary xylem is formed when the primary growth of the plant body is taking place whereas secondary xylem is formed during the secondary growth of the plant. Primary xylem is of two types that are protoxylem which is the first formed primary xylem and metaxylem which is the later formed primary xylem. On the basis of the position of protoxylem and metaxylem, there are two types of primary xylem that are endarch and exarch.
Endarch conditions exist in the stem, in this the metaxylem lies towards the periphery and the protoxylem is towards the center or the pith. Exarch conditions exist in roots in which the protoxylem lies towards the periphery and the metaxylem lies towards the center.

Note: Gymnosperms lack vessels in their xylem and due to this the presence of vessels is the characteristic feature of all angiosperms that is all the flowering plants. Gymnosperms also lack sieve tubes and companion cells from phloem tissue in them.