Question

explain a) epidermis and palisade meaophyll​

Answer 1

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Epidermis:

• It is the outermost protective covering of plants.
• It protects plants against water loss, it regulates gaseous exchange etc.
• It is a stratifed epithelium.
• Keratinocytes are the most common types of cells in epidermis.
• They provide mechanical strength to the plant.

Pallisade Cells:

• These types of plant cells are located on leaves.
• They are elongated.
• They absorb light for the photosynthesis of food.
• These cells collectively make the mesophyll cells.
• These cells contain many chloroplasts.

Answer 2

★ Definition →

• Epidermal cells generally refer to cells in the outer layer of animals and plants.

★ Epidermal cells →

• Epidermal cells generally refer to cells in the outer layer of animals and plants. Its main function is to protect and also have other functions, such as secretion of the stratum corneum. The epidermis of the green plant also has stomata , which are used to regulate the gas in and out.

The epidermal cells generally do not have chloroplasts, and the surface is mostly irregular. The side walls are often uneven. They are fitted with each other and are closely connected. There is no gap except for the stomata. The cross-section is rectangular or square. Cuticle. But the stratum corneum is not completely impermeable. Foliar fertilization is used in production. After spraying aluminum leaf on the leaf surface, part of it enters the leaf through the stomata and partly enters through the cuticle of the epidermis

★ Plant epidermis

Exterior profile of plant epidermal cells, some polygonal [e.g. prostrate Selaginella (Selaginellanipponica), cycads (Cycas revoluca), evergreen (Rhodea japonica), grapes (Vitis rinifera), etc.], some wavy Sedum [e.g. (Crassulace-ae), Solanaceae, Gramin-eae] , some are elongated spindle-shaped (for example, Torre-ya nucifera), red iris (Iris sanguinea), etc. Generally towards the outer cell wall hypertrophy, or have a cell wall outside cellulose and horny layer composed of, as well as outside of this layer is covered with a layer of the stratum corneum of. The cuticles are developed, such as the leaves of Osmanthes ilicifoli-us and the peels of apples (Malus pumila), which have a shiny surface. There are also waxes secreted on the surface, called wax films. The waxy shape is granular, rod-shaped or flat, and is mixed in the stratum corneum . Silicate crystals are contained in the cell walls of Equisetum hiemale var. Japonicum, Ulmus davidiana, and Zelkova se-rrata. In the epidermal cells of nettle (Urti-ca thunberyiana), comfrey (Lithospermum eryth-rorhizon) and other epidermal cells, stalactites are contained.

★ Animal epidermis

In animals, the epithelial cells of the skin are epidermal cells. In addition to the characteristics of general epithelial cells, they can secrete keratin and have strong keratinization characteristics, which are used to protect the epithelium and complete the function of epidermis.

★ keratinocytes

• Nickname = Epidermis

The proliferation and differentiation of keratinocytes is a process that is finely regulated, accompanied by a series of morphological and biochemical changes, and ultimately forms keratinocytes , which necessarily involves the simultaneous activation and inactivation of many structural genes , that is, the expression of genes Regulation, and regulation of transcription level is particularly important. It has been found that many transcription factors such as AP1, AP2, Sp1, POU domain and C / EBP can regulate the expression of keratinocyte genes.

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★ Meaophyll →

Assimilation tissue in plant leaves. It is composed of living cells containing chloroplasts and is the main part of photosynthesis in the leaves. There are gaps between mesophyll cells to form a ventilation system. Through the pores on the epidermis, the mesophyll cells can exchange gas with the outside world.

• Mesophyll is inside the epidermis. Mesophyll is the most developed and important part of the leaf, and is the main place for green plants to photosynthesize. The leaves of most dicotyledonous plants extend horizontally, so the upper and lower sides receive different light. The upper side (ventral surface or paraxial surface) is the light-facing side, dark green, and the lower side (back surface or distal axis surface) is light green. Mesophyll cells differentiate into two parts, palisade tissue and sponge tissue. The leaf with this structure is called the dorsal ventral leaf, also known as the two-sided leaf. However, the leaves of some plants are not differentiated by palisade tissue and sponge tissue, or have palisade tissue on the upper and lower surfaces.

★ Introduction

The tissue between the upper and lower epidermis of the leaves, except for the vascular bundle (vein), is mainly composed of thin-walled cells. It is the most developed and most important organization.

★ Structure

Mesophyll is the green tissue located on the leaf and between the epidermis and the most developed and important tissue in the leaf. Mesophyll cells contain a large amount of chloroplasts , which is the main part of photosynthesis in plants. The mesophyll cells of most plants differentiate into palisade tissue and sponge tissue. The palisade tissue is close to the epidermis and is composed of tightly arranged long cylindrical cells, mainly for photosynthesis . The sponge tissue is close to the epidermis, and is composed of loosely arranged irregular-shaped cells. The intercellular space is well developed, mainly for gas exchange and photosynthesis.