Question

Which type of vascular bundles are found in monocot stem?
A. Collateral, open indarch
B. Radial, open, diarch
C. Radial, open, mesarch
D. Collateral, closed, endarch

Answer 1

Vascular bundle is a long continuous strand of conducting tissue/vascular tissue in tracheophyte plants that extends from the root through the stem and into the leaves. It consists of the xylem and phloem, the transport itself happens in vascular tissue.

Complete answer: Vascular bundles in monocot stem are irregularly scattered in the ground tissue. Towards the periphery, the bundles are smaller in size, while towards the centre, they are larger in size. Young ones are smaller bundles, while larger ones are older. The arrangement is described as endarch. The vascular bundle encloses both xylem and phloem. Cambium is absent and hence, the vascular bundles are described as conjoint, collateral and closed. In a monocot stem, the vascular bundles are of different size, and they appear to be embedded in the ground tissue. Each vascular bundle is encircled by bundle sheath cells made up of sclerenchyma. The phloem is situated in between and above the metaxylem. Secondary vascular tissues are not formed in them as cambium is absent. Xylem transports water and minerals from the soil with the help of root hairs to the aerial parts of a plant, whereas phloem transports photosynthate to different parts of the plant.
Hence, the correct answer is option D.

Note: Xylem is composed of four different types of cells that work together as a unit. They are xylem fibres, xylem vessels, tracheids and xylem parenchyma. On the other hand, phloem is made up of phloem fibres, companion cells, sieve tubes and phloem parenchyma.