NCERT Biology Class XI: The Living World

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Qualities of life

growth, reproduction, cellular organization, metabolism, consciousness, emergent properties of life and homeostasis,

Growth

Growth is an irreversible permanent increase in size of an organ or its parts or even of an individual cell. Characteristics of growth include increase in mass and increase in number of individuals.

Reproduction

the production of progeny possessing features more or less similar to those of parents through sexual or asexual reproduction. Example: Fungi multiply and spread easily due to the millions of asexual spores they produce.

Cellular Organization

Cells are the basic unit of life and all living organisms are composed of either a single cell or many cells.

Metabolism

The sum total of all chemical reactions inside a living organism

Consciousness

The ability to sense their surroundings or environment and respond to these environmental stimuli.

Homeostasis

the ability of the body to maintain a stable internal environment despite changes in external conditions.

Adaptation

a morphological physiological or behavioural feature of an organism that is necessary for survival and reproduction in its habitat.

Biodiversity

the occurence of the number and types of organisms present on earth

Taxonomy

the study of identification, nomenclature, and classification of living organisms

Identification

A process by which an organism is recognised from the other by already known organisms and is assigned to a particular taxonomic group

Nomenclature

Naming of organisms according to international scientific rules

Binomial Nomenclature

a two-word system of providing a name to living organisms consisting of the Genus and the Species

Genus

genetic name

Species

specific epithet

Classification

A process by which any organism is grouped into convenient categories on the basis of some easily observable characters.

Artificial classification

classification on the basis of one or few superficial morphological characters like habit, color, number and shape of leaves.

Natural non-phylogenetic classification

classification where the phylogeny of plants is not considered

Natural phylogenetic classification

Classification where both gross morphology and phylogeny are considered on the basis of their evolution

Phenetic/Numerical classification

classification carried out by using computers and based on all observable characteristics

Systematics

the study of the diversity of organisms and their evolutionary relations through the study of external and internal structures, cell structure, developmental processes, and ecological information.

Taxonomic hierarchy

the descending or ascending arrangement of taxonomic catagories.

Taxon (pl. taxa)

Plant group or animal groups included in category

Suffix for division

-phyta

Suffix for class

-opsida, -phycaea, -ae

Suffix for order

ales

Suffix for family

-aceae

Biological definition of species

A species is a group of members which can interbreed naturally and produce fertile progeny and is not applied to prokaryotes since they do asexual reproduction

Taxonomic concept of species

A species is determined on the basis of morphological characters

Taxonomic species

a group of individuals having fundamental morphological similarities

Genus

Taxa which comprises of related species which ahas more characters in common in comparison to species of other genera

Family

A group of related genera characterized on the basis of vegetative and reproductive features of the species, such as Solanaceae, Convolvulaceae, Anacardiaceae, Felidae, and Canidae.

Order

related families which exhibit a few similiar characteristics and identified based on the aggregates of characters. Examples include: Polymoniales, Sapindales, Carnivora, and Primata.

Class

Related orders, such as Mammalia, Dicots, and Monocots

Phylum

Classes comprising animals like fishes, amphibians, reptiles, birds along with mammals.

Division

Classes comprising of plants with few similar characters, such as Angiospermae, Gymnospermae, Pteridophyta, and Bryophyta.

Kingdom

Animalia and Plantae