Question

In leaves, the vascular bundles are
A. Bicollateral and open
B. Collateral and open
C. Collateral and closed
D. Radial and exarch

Answer 1

Leaves are the green colour structure part of the shoot system that perform photosynthesis and transpiration due to the presence of the abundant amount of chloroplast and stomata. The vascular bundle in leaves are present in the veins of the leaf, which act as a transport medium.

Complete answer: The vascular bundle is composed of vascular tissue that is xylem and phloem when the vascular tissue arranged in long and discrete strands in the plant is called a vascular bundle. In between xylem and phloem as meristem tissue is present is called vascular cambium. Leaves lack cambium tissue in the vascular bundle which makes them closed type and which present scattered form in the mesophyll in leaves as older and larger present at the center that termed as midrib vein. Each vascular bundle has a barrel-shaped parenchyma cell that covers the xylem and phloem, which form a conjoint, collateral closed vascular bundle. When in the vascular bundle the xylem and phloem present side by side, then they form radial bundle in case of conjoint vascular bundle xylem and phloem are separated which is found in the leaf. The conjoint vascular bundle can be bi-collateral or collateral. Bicollateral or collateral and closed type of vascular bundle found in leaves and monocot stem. In which xylem and phloem present on the same radius and cambium is absent. Bicollateral and open type of vascular bundle found in dicot stem in which xylem and phloem are on the same radius along with vascular cambium. Radial type of vascular bundle found in the root.
Hence, the correct option is C.

Note: The leaves possess stomatal opening which is guard by guard cell and subsidiary cell, in monocots the bulliform cells are present. Mesophyll tissue is found in leaves, which is divided into spongy palisade tissue.