Disease refers to any condition that disturbs or modifies the normal functioning of the living organisms. Each organ system of our body has specific organs to perform particular functions. In the presence of a disease, functioning or the appearance of one or more systems of the body may change. These changes give rise to symptoms and signs of disease.
First level of classification among plants depends on whether the plant body possesses well-differentiated distinct cellular components or not. Next level is based on the presence or absence of special vascular tissues for the transport of water and other substances. Further classification takes into account the ability to bear seeds and whether seeds are enclosed within the fruits or not.
Depending on these characteristics, kingdom-Plantae is divided as of Thallophyta, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms.
Based on morphology, animal tissues can be grouped into four basic types. Multiple tissue types comprise organs and body structures. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism.
The four basic Animal Tissues are: (i) Epithelial Tissue; (ii) Connective Tissue; (iii) Muscular Tissue; and (iv) Nervous Tissue.
To know about a cell, its history, structure and functions is where the serious study of biology as a subject …