Question

Xylem in dorsiventral leaves directed towards
A. Upper epidermis
B. Lower epidermis
C. Surrounds phloem
D. Surrounded by phloem

Answer 1

Hint: Leaves that have two surfaces, a dorsal surface and a ventral surface, are called dorsiventral. The top of the leaf is directly exposed to sunlight. Such types of leaves are found in dicots. The vascular bundle is in contrast to the stem, and has an inverse orientation to the vascular tissue.

Complete answer:
Let’s first of all study about characteristics of dorsiventral leaf
In dicots there is differentiation of leaf into the upper and lower epidermis and the mesophyll, which lies between the two epidermises.
 Mesophyll consists of a palisade and spongy parenchyma. Palisade cells are elongated and are in a plane transverse to the upper epidermis. The spongy parenchyma cells have more or less isodiametric shape and are located between the palisade and the lower epidermis with abundant intercellular spaces.
The distribution of the stomata is usually limited to the lower epidermis.
The vascular lines in the cross section of the leaf are of different sizes and are not in transverse lines. The vascular bundle is usually surrounded by a bundle sheath consisting of a single parenchyma layer.
Numerous vascular bundles are scattered in the spongy parenchyma. The vascular bundle is surrounded by a large parenchyma sheath or marginal parenchyma. Collenchyma can also be associated with bundle cells. Xylem is located towards the upper epidermis and phloem towards the lower epidermis.

Hence, the correct answer is option (A).

Note: The vascular bundle size depends on the location selected when creating the part. An incision through the midrib shows vascular bundles with xylem and phloem, xylem with tracheids, veins, etc. Phloem in dorsiventral leaves consists of companion cells and sieve tubes. Some phloem parenchyma cells lie towards lower epidermis.
In the dorsive central leaf the single median vein bundle is larger and several small vein bundles are smaller. Smaller vascular bundles are freely distributed in mesophilic cells of leaves.