NCERT 11TH STANDARD BIOLOGY – ANIMAL TISSUES The structure of the cells vary according to their function. Therefore, the tissues are different and are broadly classified into four types : (i) Epithelial, (ii) Connective, (iii) Muscular and (iv) Neural. Epithelial Tissue We commonly refer to an epithelial tissue as epithelium (pl.: epithelia).This tissue has a …
NCERT 11TH STANDARD BIOLOGY – ANIMAL KINGDOM – INTRODUCTION When you look around, you will observe different animals with different structures and forms. As over a million species of animals have been described till now, the need for classification becomes all the more important. The classification also helps in assigning a systematic position to newly …
NCERT 11TH STANDARD BIOLOGY – ANATOMY OF FLOWERING PLANTS Study of internal structure of plants is called anatomy. Plants have cells as the basic unit, cells are organised into tissues and in turn the tissues are organised into organs. Different organs in a plant show differences in their internal structure. Within angiosperms, the monocots and …
NCERT 11TH STANDARD BIOLOGY – ANATOMY OF DICOTYLEDONOUS AND MONOCOTYLEDONOUS PLANTS Dicotyledonous Root The internal tissue organisation is as follows: The outermost layer is epiblema. Many of the cells of epiblema protrude in the form of unicellular root hairs. The cortex consists of several layers of thin-walled parenchyma cells with intercellular spaces. The innermost layer …
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NCERT 11TH STANDARD BIOLOGY – PLANT LIFE CYCLES AND ALTERNATION OF GENERATIONS In plants, both haploid and diploid cells can divide by mitosis. This ability leads to the formation of different plant bodies – haploid and diploid. The haploid plant body produces gametes by mitosis. This plant body represents a gametophyte. Following fertilisation the zygote …
NCERT 11TH STANDARD BIOLOGY – ANGIOSPERMS Unlike the gymnosperms where the ovules are naked, in the angiosperms or flowering plants, the pollen grains and ovules are developed in specialised structures called flowers. In angiosperms, the seeds are enclosed in fruits. The angiosperms are an exceptionally large group of plants occurring in wide range of habitats. …
NCERT 11TH STANDARD BIOLOGY – GYMNOSPERMS The gymnosperms (gymnos : naked, sperma : seeds) are plants in which the ovules are not nclosed by any ovary wall and remain exposed, both before and after fertilisation. The seeds that develop post-fertilisation, are not covered, i.e., are naked. Gymnosperms include medium-sized trees or tall trees and shrubs. …
NCERT 11TH STANDARD BIOLOGY – PTERIDOPHYTES The Pteridophytes include horsetails and ferns. Pteridophytes are used for medicinal purposes and as soil-binders. They are also frequently grown as ornamentals. Evolutionarily, they are the first terrestrial plants to possess vascular tissues – xylem and phloem. The pteridophytes are found in cool, damp, shady places though some may …
NCERT 11TH STANDARD BIOLOGY – BRYOPHYTES Bryophytes include the various mosses and liverworts that are found commonly growing in moist shaded areas in the hills Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction. They usually occur in damp, humid …
NCERT 11TH STANDARD BIOLOGY – ALGAE Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic (both fresh water and marine) organisms. They occur in a variety of other habitats: moist stones, soils and wood. Some of them also occur in association with fungi (lichen) and animals (e.g., on sloth bear). The form and size of …