Tag: internal structure of root, stem and leaf

Palisade parenchyma cells are plant cells found within the mesophyll in leaves, right below the upper epidermis and cuticle. They are vertically elongated, a different shape from spongy mesophyll cells beneath them in the leaf. Their chloroplasts absorb a major portion of the light energy used by the leaf. 

Palisade cells are plant cells found within the mesophyll in leaves, right below the upper epidermis and cuticle. They are vertically elongated, a different shape from spongy mesophyll cells beneath them in the leaf. Their chloroplasts absorb a major portion of the light energy used by the leaf. Palisade cells occur in dicotyledonous plants and also in the net-veined monocots. The spongy mesophyll are usually ball-shaped with large intercellular spaces but usually contains fewer chloroplasts than the palisade cells. They are also present in dicot leaf. 

Stomata is a pore, found in the epidermis of leaves, used to control gas exchange. The pore is bordered by a pair of specialized parenchyma cells, known as guard cells that are responsible for regulating the size of the opening. Stomata are present in the sporophyte generation of all land plant groups except liverworts. 

Dorsiventral leaf i.e. Mesophyll is the ground tissue and it occurs between the two epidermal layers. It is heavily composed of chlorenchyma cells. The mesophyll is differentiated into two regions an upper palisade parenchyma and lower spongy parenchyma. Palisade parenchyma is again composed of two or three layers of elongated and compactly arranged chlorenchyma cells.

Also, the isobilateral leaf has undifferentiated mesophyll.

Therefore, the correct answer is option B.

Leaves, in which both surfaces are differentiated are called dorsiventral leaves. In these leaves, palisade parenchyma is present towards the upper epidermis and spongy parenchyma is present towards the lower epidermis. Because of this reason, in dorsiventral leaves, the upper side is dark green in colour and lower side is light green in colour.

So, the correct answer is ‘Upper surface is dark green as compared to the lower surface’.

The parenchyma with loosely arranged cells, present in the mesophyll of leaves is called spongy parenchyma.

So, the correct option is ‘Loosely arranged’

In xerophytic leaves, mesophyll is differentiated into palisade and spongy parenchyma. In these leaves, palisade parenchyma is present on both sides. i.e towards upper epidermis and lower epidermis. In the palisade parenchyma cells are cylindrical in shape contains more number of chloroplasts. In spongy parenchyma, cells are oval in shape, loosely arranged, with less number of chloroplasts. 

The region present between the upper and lower epidermis of leaves is called mesophyll. It is differentiated into upper palisade and lower spongy parenchyma in dicot leaves or dorsiventral leaves, whereas in monocot leaves or isobilateral leaves, it is undifferentiated and it shows spongy parenchyma.

So, the correct option is ‘All dorsiventral leaves’.

a-bulliform cells                3) Grasses

b)Pericycle                         1) Initiation of lateral roots

c)Endarch xylem                5)stem

d)Exarch xylem                  2)Root

e)Bundle sheath cells       3)Grasses

So, the correct option is ‘a-3, b-1, c-5, d-2, e-4