Plant and Animal Tissues Test - 5

Apical meristem is present at the growing tips of stems and roots and increases the length of the stem and the root. The girth of the stem or root increases due to lateral meristem (cambium). Intercalary meristem is the meristem at the base of the leaves or internodes (on either side of the node) on twigs.

Epithelial tissues help in protection,secretion and sensory perception. Functions of epithelial cellsinclude secretion, selective absorption, protection,transcellular transport, and sensing. Epithelial layerscontain no blood vessels, so they must receive nourishment via diffusion ofsubstances from the underlying connective tissue, through thebasement membrane. Epithelial tissues do not providesupport. 

Vascular tissues are permanent tissues witha complex make up. So, they can be easily described as Complex Permanenttissues. Complex tissues are made of more than one typeof cells. All these cells coordinate to perform a common function. Xylem and phloemare examples of such complex tissues. They areboth conducting tissues and constitute a vascular bundle.

In vascular tissues, xylem and phloem run throughout the plant and are involved in transport of materials within the plant. Xylem and Phloem tissues are present throughout the plant. They begin at the root and then move up to the stem, branches, and leaves. The xylem tissue transports water and minerals from the roots to the leaves whereas the phloem tissue transports food from the leaves to the other parts of the plant.

Tendons are dense connective tissues containing only fibroblasts and collagen fibres. Crowded between the collagen fibers are rows of fibroblasts, fiber-formingcells, that generate the fibers. Dense connective tissue forms strong, rope-like structures such as tendons and ligaments. Tendons attach skeletal muscles to bones; ligaments connect bones to bones at joints.

Permanent tissues are made up of cells that do not divide. They are classified into threetypes- dermal tissue, ground tissue and vascular tissue. Dermaltissue coversand protects the plant, and vascular tissue transportswater, minerals, and sugars to different parts of the plant. Groundtissue serves as a site for photosynthesis, provides a supportingmatrix for the vascular tissue, and helps to store water andsugars.

Parenchyma cells are thin walled, round or oval shaped, contain leucoplasts and store food.
They are present in the stem, leaves and flowers of the plant. Parenchymas are thin-walled round or oval shaped cells having spaces between them. It is present in stem, leaves, flowers, fruits and seeds. Most of them contain leucoplast and store food. Chloroplast containing parenchyma is called chlorenchyma and deal with photosynthesis.

Adipose tissue stores energy in the form offats. Adipose tissue, or fat, is an anatomical term forloose connective tissue composed of adipocytes.Its main role is to store energy in the form of fat, although italso cushions and insulates the body.

Leucocytes or white blood cells protect thebody from diseases. White blood cells (WBCs), also called leukocytes or leucocytes,are the cells of the immune system that are involved in protectingthe body against both infectious disease and foreigninvaders. Leukocytes are found throughout the body,including the blood and lymphatic system.

Heart muscle is a type of musculartissue and not connective tissue. Cardiac and skeletal muscles are "striated"in that they contain sarcomeres and are packed into highly regular arrangementsof bundles; smooth muscle has neither. While skeletal musclesare arranged in regular, parallel bundles, cardiac muscle connectsat branching, irregular angles (called intercalated discs).

Vascular Tissues are also known asconducting tissues. Vascular tissue is a complex conducting tissue, formedof more than one cell type, found in vascular plants. Theprimary components of vascular tissue are the xylem and phloem.These two tissues transport fluid and nutrients internally.

The columnar epithelium is found in theintestines, stomach and gall bladder. The alveoli are lined bysimple squamous epithelial cells. Most of therespiratory passageways, from the nasal cavity through the bronchi,are lined by ciliated, pseudo stratified columnarepithelium with goblet cells. Bronchioles are lined bysimple cuboidal epithelium. (Lung alveoli, in contrast,are lined by very thin simple squamous epithelium.)

Nucleus is absent in RBC. The absenceof a nucleus is an adaptation of the red blood cell forits role. It allows the red blood cell to contain morehaemoglobin and, therefore, carry more oxygen molecules. It also allows thecell to have its distinctive bi-concave shape which aids diffusion.

Phloem consistsof living cells, primarily sieve tube cells and companion cells. Phloem tissue consists ofconducting cells, generally called sieve elements,parenchyma cells, including both specialized companioncells or albuminous cells and unspecialized cells andsupportive cells, such as fibres and sclereids.