Microscopy The studies of living organisms of microscopic dimensions, its development depended entirely upon the refinement of the microscope. Type of microscopy 1.Simple Microscope In the 17th century A. van Leeuwenhoek was used single-lens microscopes of the simplest possible design.He could make lenses and using them to build magnifying glasses to provide a magnification of about 200. 2. Compound Microscope In the 18th century, Robert Hooke had used a compound microscope 3. Bright-field (Light) microscopy The light microscope is a two-lens system in which the lens nearest the object is known as the objective lens and that nearest the eye, is known as the ocular lens. Visible light rays are projected through a condenser that focuses them into a sharp cone, then sends them through the opening in the stage on which the slide rests. The light passes through the slide, bounces off the object, then passes through the objective lens to form a magnified image darker than the ba
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CONCEPT OF ECOLOGICAL NICHE 1. Spatial/ Habitat Niche (The Concept of Grinell): It was first defined by Grinell in 1904. According to Grinell, niche corresponded to habitat. It concerns the physical space occupied by an organism. Eg. the Distribution of seven species of millipedes in the forest floor of maple oak forest. 2. Tropic Niche (The Concept of Odum): Definition of the niche was given by Odum in 1971. It is concerned with the trophic position of an organism. Eg. Occurance of various species of birds in Galapagos island. Odum had stated that the habitat of an individual represents an addres s , the ecological niche a profession. However, under the term of the profession 3. Hypervolumic Niche(The concept of Hutchinson) Hutchinson combined the idea of habitats and function. His concept of ecological niche is based on multidimensional hypervolum e (n-dimensional), where the dimensions are environmental conditions and resources, which describe the
OBJECTIVE QUESTION BASED ON SPECIES AND POPULATION ECOLOGY Allopatric speciation occurs when (a) genetically unrelated populations inhabit the geographical area (b) genetically related populations same geographical area (c)genetically unrelated populations inhabit widely separated geographical area (d) genetically related populations inhabit widely separated geographical areas. 2. Asymptote is the stage when a population is (a) Stabilised (c) Increasing (b) Changing (d) Decreasing In the exponential phase, the sequence of events in bacterial multiplication is (a) stationary, lag, log, decline (b) stationary, log, lag, decline (c) lag, log, decline, stationary (d) decline, log, lag, stationary 4. Two species cannot occupy the same niche. The law is (a) Wein Law (b) Allen Law (c) Gause Law (d) Competition