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Biology questions set 007

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complex plant tissues

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BIOLOGY complex plant tissues Tracheids : Cells are dead, long with transverse ends, containing large vacuole. Cell walls are hard, strong. and lignified. Their main functions are to give mechanical strength and to supply water and dissolved minerals from root to the leaves.Complex tissue is composed of more than one kind of cells. They are two types, namely Xylem tissue and Phloem tissue.  Tracheid  Xylem tissue : Xylem tissue consists of four types of cells, namely: Tracheids, Vessels or Trachaea, Xylem fibre and Xylem Parenchyma.  Vessel  Vessels or Trachaea: Cells are broad and short, placed end to end to form a continuous hollow tube. Water and waterdissolved minerals are conducted from root to leaf by these cells.   �Xylem fibre: These are sclerenchymatous cells. Their main function is to give mechanical strength to the plant. Xylem parenchyma: These are parenchymatous . cells. Functions of these cells are storage and conduction of food materials. Func...
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animal tissue organ and organ system

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ANIMAL TISSUE, ORGAN AND ORGAN SYSTEM There is only one cell in the body of the animals of the phylum Protozoa. Animals of the Phylum Porifera are simplest multi-cellular animals. Their cells do not form actual tissue. Though tissues, organs and systems are not formed in members of the phylum Cnidaria (previously known as Coelenterata), their body cells are, however, arranged in two layers. In the animals from phylum Platyhelminthes to Chordata, tissues, organs and organ systems are seen. Members of those phyla are three layered. From there three embryonic cell layers (namely ectoderm, mesoderm and endoderm), tissues, organs and systems are formed. Tissue : In the body of multi-cellular animals some cells remain together and performa particular function. These cells are either formed from the ectoderm, mesoderm or endoderm of the embryo and remain close together. Inter-cellular materials or matrix are present between these cells. These cells may be similar or of different types. Arisin...
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Division Of Labour In Multicellular Plants

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Division Of Labour In Multicellular Plants : Tissue and Tissue System Tissue : In unicellular organisms a single cell does all the functions. There is no chance of division of labour on the basis of cell. In contrast, this kind of division is found in multicellular living body. In this case, it is observed that a group of cells performs the duty of manufacturing food; another group stores it, while the other group conducts the transport of food materials. There is further a group of cells that gives mechanical strenght to some organs. In many cases it is observed that a group of cells originating from a single origin remain closely attached in a place and collectively perform a similar type of function. This type of cells in a group is called tissue. In multicellular organisms division of labour is the main cause of formation of tissue. Types of Tissue : Cells of all tissues do not have the power of cell division but some of them have. Therefore tissues are of two types in terms of t...
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