Question

In a dicot leaf, vascular bundles are found in the
A. Chloroplast
B. Palisade tissue
C. Lower epidermis
D. Upper epidermis
E. Spongy mesophyll

Answer 1

Hint: Leaf is a green, thin and flat plant organ. These are lateral appendages of stem with limited growth that contain chlorophyll pigment in the chloroplast which is required for the photosynthesis process.

Complete answer:
The dicot leaf has following layers:
> Upper epidermis- It is a single layer composed of a row of compactly arranged parenchyma cells that are cutinized and possess a thick cuticle on the outer surface of upper epidermis. Stomata are generally absent.
> Mesophyll- This is present between the upper and lower epidermis and it is a chlorophyll containing photosynthetic tissue. It is divided into two parts- Palisade and spongy parenchyma.
Palisade parenchyma is present below the upper epidermis and consists of closely elongated cells. They have abundant chloroplasts.
Spongy parenchyma is present below palisade tissue and consists of loosely arranged irregularly shaped cells with large intercellular spaces in between them. It is in contact with the atmosphere through the stomata.
> Vascular system- There are many vascular bundles in this layer. Each vascular bundle is surrounded by a thin layer of parenchymatous cells called bundle sheath. Each vascular bundle has xylem towards upper epidermis and phloem towards lower epidermis. Xylem helps in conduction of water and phloem helps in conduction of food.
Each vascular bundle is conjoint and collateral. The xylem is made up of treachery elements, xylem parenchyma and few xylem fibres.
Each vascular bundle is surrounded by bundle sheath which is made up of closely packed parenchymatous cells. Bundle sheath extension may be present on the both sides of vascular bundles that are made up of parenchyma or collenchyma cells.
The vascular bundles are found in the spongy parenchyma.