Algae are a group of autotrophic, non-vascular thalloid plants with chlorophyll and without any formation of embryo. They are mostly photosynthetic in nature. The plant body may be unicellular, colonial or multicellular. Algae possess a simple plant body which is called thallus. The thallus is not differentiated into true root, stem and leaves. They also … Read more
Diatoms are unicellular, eukaryotic microalgae which are found in marine water, freshwater, soil and many moist places. They are microscopic organisms and mostly live as plankton in water bodies. Diatoms are important member of phytoplankton and they perform photosynthesis like green plants. The most characteristic feature of diatoms is the presence of hard outer wall … Read more
Algae are a group of autotrophic, photosynthetic and non-vascular organisms. They may be unicellular or multicellular in nature. Some algae are microscopic like phytoplankton, while some are large multicellular forms like giant kelp. Algae contain chlorophyll and prepare their food by photosynthesis. During this process they release oxygen and form organic food materials. For this … Read more
Eyespot help in cell’s phototaxis, it senses the intensity and direction of light source and responds to it. In response, it helps the organism in swim towards the light (positive phototaxis), or away from it (negative phototaxis).
Dark field microscopy is a special illumination technique used in light microscope to increase contrast of transparent, unstained or low contrast specimens. The specimen looks bright, and the background looks dark or almost black. It is useful when normal bright background observation is not giving clear contrast. It is done by using a modified condenser … Read more
Fluorescence microscope is an advanced optical microscope that uses fluorescence for viewing the specimen. It produces a bright coloured image of the specimen in a dark background. It is mostly used for biological and chemical samples where a specific part of the sample is to be seen clearly. In this microscope, fluorescent dyes, proteins or … Read more
Oil immersion technique is a light microscopic technique used for increasing the resolving power of microscope at high magnification. In this technique, a special transparent oil is used between the cover glass and the objective lens. This oil is called immersion oil. It is mostly used with oil immersion objective lens. Normally, when light passes … Read more
Transmission Electron Microscope (TEM) is an advanced analytical instrument used to visualize the internal structure of specimens. It uses highly energetic beam of electrons instead of light. It works under high vacuum condition. The electron gun produces electron beam. This beam is then focused and guided by a series of electromagnetic lenses. The specimen used … Read more
Scanning Electron Microscope (SEM) is an advanced magnifying instrument that is used to observe the surface of a sample by using focused beam of accelerated electrons. It does not use visible light for image formation. It uses electron beam because electrons have much shorter wavelength than light photons. So, SEM can produce image with very … Read more
Phase contrast microscope is an optical microscope that is used to observe transparent and unstained living cells. It converts small phase changes of light into visible contrast. These phase changes are produced when light passes through the different parts of the specimen. It was developed by Frits Zernike in 1930s. This microscope is very useful … Read more
