Diversity in living organisms
Top definitions
1) Classification – The method of arranging organisms into groups on the basis of similarities and differences.
2) Characteristic – A distinguishing feature of an individual or group.
3) Evolution – A gradual and continuing process of change in body design of organisms, occurring over a period of time due to various factors, which leads to better survival of organisms as well as development of new species.
4) Biodiversity – The variety of life forms found in a particular region.
5) Regions of megadiversity – Regions rich in diversity of plant and animal life.
6) Habitat – The natural abode of an animal or plant.
7) Species – It refers to all organisms that are similar enough to breed and perpetuate.
8) Saprophytes – Organisms obtaining their nourishment from dead and decaying organic material.
9) Lichens - Symbiotic associations of certain fungi with blue-green algae.
10) Cotyledon - Embryonic leaf in seed-bearing plants.
11) Monocots – Plants with seeds having a single cotyledon.
12) Dicots - Plants with seeds having two cotyledons.
13) Bilateral symmetry- Symmetrical arrangement of an organism along a central axis, so that the body is divided into equivalent right and left halves by only one plane.
14) Radial symmetry –A type of symmetry having only one body axis, through which the body can be divided in multiple planes to give mirror
image halves OR
A form of symmetry, in which dividing the animal's body in any direction along the central axis would always result in 2 identical halves being obtained.
15) Notochord - A long flexible rod-shaped support structure that runs along the back of the animal separating the nervous tissue from the gut.
16) Nerve cord - A dorsal tubular cord of nervous tissue above the notochord of a chordate.
17) Diploblastic animals - Animals having 2 primary germ layers i.e.
ectoderm and endoderm in the embryo.
18) Triploblastic animals - Animals having 3 primary germ layers i.e.
ectoderm, mesoderm and endoderm in the embryo.
19) Ectoderm – The outermost germ layer of multicellular animals that develops into skin and nervous tissue.
20) Endoderm - The innermost germ layer of multicellular animals that develops into the lining of the digestive and respiratory systems.
21) Mesoderm - The middle germ layer that develops into muscle and bone and cartilage and blood and connective tissue.
22) Acoelomates – Animals lacking a body cavity between their gut and body wall.
23) Coelom - A fluid filled cavity formed within the mesoderm, in which well-developed organs can be accommodated.
24) Pseudocoelom - An internal body cavity of some primitive invertebrates, similar to a coelom but lacking a mesodermal lining.
25) Coelenteron – The central gastrovascular cavity of a coelenterate animal.
26) Cold-blooded organisms – Organisms whose body temperature varies according to the external environmental temperature.
27) Warm-blooded organisms – Organisms whose internal body temperature is dependent upon its metabolic processes and is maintained at a constant level.
28) Oviparous animals – Animals that lay eggs.
29) Viviparous animals – Animals giving birth to live young ones.
30) Binomial nomenclature – The scientific system of naming each species of organism with two names, a genus name and a species name.
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NCERT 9 Science