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14.6 ECOLOGICAL SUCCESSION

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14.6 ECOLOGICAL SUCCESSION You have learnt in Chapter 13, the characteristics of population and community and also their response to environment and how such responses vary from an individual response.  Let us examine another aspect of community response to environment over time.  Bcological succession:   The gradual and fairly predictable change in the species composition of a given area is called ecological succession. An important characteristic of all communities is that composition and structure constantly change in response to the changing environmental conditions.  This change is orderly and sequential, parallel with the changes in the physical environment.  These changes lead finally to a community that is in near equilibrium with the environment and that is called a climax community.   Sere(s):  The entire sequence of communities that successively change in a given area are called sere(s).  The individual transitiona...
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WHAT ARE THE EVIDENCES FOR EVOLUTION? NEET (part-1)

7.3 WHAT ARE THE EVIDENCES FOR EVOLUTION? Evidence that evolution of life forms has indeed taken place on earth has come from many quarters.  Paleontological evidence . Fossils are remains of hard parts of life-forms found in rocks.  father of Indian paleontology- Birbal Sahani Rocks form sediments and a cross-section of earth's crust indicates the arrangement of sediments one over the other during the long history of earth.  Different-aged rock sediments contain fossils of different life-forms who probably died during the formation of the particular sediment.  Some of them appear similar to modern organisms.  They represent extinct organisms (e.g., Dinosaurs).  Birds  are the only surviving  dinosaurs . A study of fossils in different sedimentary layers indicates the geological period in which they existed.  The study showed that life-forms varied over time and c...
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Figure 7.9 A sketch of the evolution of plant forms through geological periods NEET

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Figure 7.9 A sketch of the evolution of plant forms through geological periods NEET Expectations/ practice 1. Match the following 2. Find the correct sequence Coenozoic    Quaternary Angiosperm (flowering plants) Monocotyledons Tertiary Bryophytes Measozoic    Cretaceous Shenopsids (horsetails), Ginkgos, Gnetales, Dicotes Jurassic Herbaceous lycopods, Ferns, Conifers and Cycads Triassic Paleozoic Permian Arborescent lycopods Carboniferous Seed ferns Devonian Progynmnosperm Silurian Zosterophyllum Chlorophyte ancestors > Tracheophyte ancestor > Rhynia-type Plants > Psilophyton Chlorophyte ancestor > Bryophytes Chlorophyte ancestors > Tracheophyte ancestor > Zosterophyllum > Arborescent lycopods > Herbaceous lycopods Chlorophyte > Tracheophyte > Rhynia-type Plants > Psilophyton > Shenopsids (horsetails) Chlorophyte > Tracheophyte > Rhynia-type Pla...
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