Tag: internal structure of leaf (dicot and monocot)

In a dorsiventral leaf the phloem is present towards the lower surface of the leaf. Xylem lies towards upper epidermis and is composed of annular and spirally thickened vessels, tracheids, fibres and xylem parenchyma. The vascular bundles are conjoint, closed and collateral. Mid vein bundle is large, while others are small. 

Palisade cells contain the largest number of chloroplasts per cell, which makes them the primary site of photosynthesis in the leaves of those plants that contain them, converting the energy in light to the chemical energy of carbohydrates. Beneath the palisade mesophyll are the spongy mesophyll cells, which also perform photosynthesis. Spongy cells acts well in high intensity light.

In dorsi ventral leaf, mesophyll is the ground tissue that occurs between the two epidermal layers. It is exclusively composed of chlorenchyma cells. The mesophyll is characteristically differentiated into two regions namely, an upper palisade parenchyma and a lower spongy parenchyma. Palisade parenchyma is composed of two or three layers of elongated, compactly arranged chlorenchyma cells. Intercellular spaces are absent. The cells contain a very large number of chloroplasts. Spongy parenchyma is composed of a few layers of loosely arranged spherical or oval chlorenchyma cells with prominent intercellular spaces. These cells contain very few chloroplasts. In isobilateral leaf, mesophyll is ground tissue that occurs between the two epidermal layers. It is composed of many layers of loosely arranged, spherical or oval chlorenchyma cells. Intercellular spaces are prominent. Mesophyll is not differentiated in spongy and palisade tissue. 
Therefore, the correct answer is option B.

Dorsiventral leaf - Mesophyll is the ground tissue that occurs between the two epidermal layers. It is exclusively composed of chlorenchyma cells. The mesophyll is characteristically differentiated into two regions namely, an upper palisade parenchyma and a lower spongy parenchyma. Palisade parenchyma is composed of two or three layers of elongated, compactly arranged chlorenchyma cells. Intercellular spaces are absent.

In dorsiventral leaves, mesophyll is the ground tissue that occurs between the two epidermal layers. It is exclusively composed of chlorenchyma cells. The mesophyll is characteristically differentiated into two regions namely, an upper palisade parenchyma and a lower spongy parenchyma. Dorsiventral leaves are present in dicots. In an isobilateral leaves, undifferentiated mesophyll is present. These leaves are present in monocots. Dorsiventral leaves are absent in extremely xerophytic leaves and hydrophytic leaves. 
Thus, the correct answer is option D.

Stoma (plural stomata) is a pore, found in the epidermis of leaves, stems and other organs that is used to control gas exchange. Monocots have isobilateral leaf and dicots have dorsiventral leaf. Dicotyledons usually have more stomata on the lower epidermis than the upper epidermis. Monocotyledons, on the other hand, usually have the same number of stomata on the two epidermis. In plants with floating leaves, stomata may be found only on the upper epidermis and submerged leaves may lack stomata entirely.
Thus, the correct answer is option B.

In the dorsiventral leaf or dicot leaf, mesophyll is differentiated into palisade parenchyma and spongy parenchyma. Palisade parenchyma is present on the upper side and spongy parenchyma is present on the lower side.

The region present between the upper and lower epidermises is called mesophyll. In dicot leaves, mesophyll is differentiated into upper palisade parenchyma and lower spongy parenchyma. It is found in dicot leaves.

So, the correct answer is ‘Dicot leaves’

In dorsiventral leaf, more number of stomata occur on lower epidermis and less number of stomata present on upper epidermis.

So, the correct option is ‘occur on lower epidermis'.