SCIENCE PROJECT WORK

TOPIC TISSUES

INTRODUCTION

Tissue, group of associated, similarly structured cells that perform specialized functions for the survival of the organism (see Physiology). Animal tissues, to which this article is limited, take their first form when the blastula cells, arising from the fertilized ovum, differentiate into three germ layers: the ectoderm, mesoderm, and endoderm

PLANT TISSUEThere are many variants of the generalized

plant cell and its parts. Similar kinds of cells are organized into structural and functional units, or tissues, which make up the plant as a whole, and new cells (and tissues) are formed at growing points of actively dividing cells.

plant tissue

Meristematic permanent

MERISTEMATIC TISSUE There are many variants of the generalized plant cell

and its parts. Similar kinds of cells are organized into structural and functional units, or tissues, which make up the plant as a whole, and new cells (and tissues) are formed at growing points of actively dividing cells. These growing points, called meristems, are located either at the stem and root tips (apical meristems), where they are responsible for the primary growth of plants, or laterally in stems and roots (lateral meristems), where they are responsible for secondary plant growth.

meristematic tissue Apical intercalary lateral

APICAL MERISTEMThis lengthwise section through the tip of a plant root reveals the apical meristem, characterized by rapidly dividing cells that are responsible for primary growth. Apical meristem can also be found at the tips of stems where they are responsible for secondary plant growth. Three tissue systems are recognized in vascular plants: dermal, vascular, and ground.

INTERCALARY MERISTEM

Intercalary meristem Is the meristem at the base of the leaves or internodes on either side of the node on twigs.

Lateral meristemLateral meristem is the meristem that

increases the girth of the stem or root

PERMANENT TISSUEParenchyma tissue makes up most of the pith and cortex of trees, the photosynthetic tissue in leaves. Collenchyma cells mainly form supporting tissue. They are found in the cortex of stems. The major function of sclerenchyma is support. mature cells of this tissue are generally dead and have thick walls containing lignin.

EPIDERMAL CELLSEpithelial tissue forms a protective layer of cells that covers organ surfaces and lines body cavities. Shown here is a layer of simple squamous (scaly) epithelium under magnification. Cancers that arise in epithelial tissues, called carcinomas, account for approximately 90 percent of all human cancers.

COMPLEX PERMANENT TISSUE complex tissues include the dermal and vascular tissues of plants. The epidermis is the outermost layer of cells on the plant body. It covers the leaves, stems, and roots, as well as the flower parts and seeds. In most plants the epidermis is only one cell-layer thick. The epidermal cells are closely packed. When viewed through a microscope, they resemble a stone pavement

ANIMAL TISSUEEpithelial tissue forms a protective layer of cells that covers organ surfaces and lines body cavities. Shown here is a layer of simple squamous (scaly) epithelium under magnification. Cancers that arise in epithelial tissues, called carcinomas, account for approximately 90 percent of all human cancers.

CONNECTIVE TISSUEConnective tissues include bone, cartilage, fat, ligaments, and tendons. These tissues support and connect parts of the body. The structure varies depending on the purpose of the tissue. The diagonal red band in this image shows elastin fiber, which allows connective tissue to spring back into shape following deformation.

TYPES OF CONNECTIVE TISSUE

MUSCULAR TISSUEMuscle, tissue or organ of the animal body

characterized by the ability to contract, usually in response to a stimulus from the nervous system. The basic unit of all muscle is the myofibril, a minute, threadlike structure composed of complex proteins. which are composed of regularly arranged myofilaments of two types, thick and thin. eserved.

TYPES OF MUSCLES

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DONE BY pavan