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TLB’S Biology Classes, , THE LIVING WORLD, PART 1, , Characteristics exhibited by living organisms, • Growth, • Reproduction, • Metabolism, • Cellular organisation of the body, • Ability to sense environment, • Consciousness, , Growth, • All living organisms grow, • Increase in mass and increase in number of individuals are twin, characteristics of growth., • Unicellular organisms and multi cellular organism grow by cell division., , What is the difference between the growth of Plants and Animals ?, • In plants, growth by cell division occurs continuously throughout their life, span., • In animals, growth is seen only up to a certain age., Why growth is not considered as a defining property of living things., • Non-living objects also grow if we take increase in body mass as a, criterion for growth., •, , Mountains, boulders and sand mounds do grow., , •, , However, this kind of growth exhibited by non-living objects is by, , •, •, , accumulation of material on the surface., In living organisms, growth is from inside., In non living things growth is an external property., , •, , Growth, therefore, cannot be taken as a defining property of living, organisms.

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TLB’S Biology Classes, , REPRODUCTION, • In multicellular organisms, reproduction refers to the production of, progeny possessing features more or less similar to those of parents, • Two types of Reproduction are there ,Sexual reproduction and, , Asexual reproduction, , Examples for Asexual reproduction, • Fungi multiply and spread easily due to the millions of asexual spores, • In lower organisms like yeast and hydra, reproduction is by budding., • In Planaria (flat worms), reproduction is by regeneration., • The fungi,the filamentous algae, the protonema of mosses, all easily, multiply by fragmentation., , Why reproduction cannot be considered as an all-inclusive defining, characteristic of living organisms., • Unicellular organisms like bacteria, unicellular algae or Amoeba,, reproduction is synonymous with growth, i.e., increase in number of cells, is growth as well as reproduction., • There are many organisms which do not reproduce (mules, sterile worker, bees, infertile human couples, etc)., • Hence, reproduction also cannot be an all-inclusive defining characteristic, of living organisms.