Palaemon: Diagram, Characteristics, Classification, Morphology and Reproductive System
Palaemon (The Freshwater Prawn) is studied in the Indian Universities as a typical representative of the class Crustacea.
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Vaccines: Definition, Types and Production of Vaccines
Vaccines (Latin: vacca = cow) preparation/suspension or extract of dead/attenuated (weakened) germs of a disease which, on inoculation (injection) into a healthy person, provides temporary/permanent active/passive immunity by inducing antibody formation.
HIV/AIDS virus: Structure, Symptoms, Treatment, Prevention and Mode of Action
What is HIV/AIDS virus? HIV (Human immunodeficiency virus) is a retrovirus that belongs to the genus Lentivirus, part of the family Retroviridae. It is the causative agent of AIDS (Acquired Immunodeficiency Syndrome).
Phylum Arthropoda: Definition, Characteristics, Classification and Examples
Phylum Arthropoda (Gr., arthros = jointed ; podos = foot) is the largest and most diverse group of animals in the animal kingdom, characterized by their segmented bodies, jointed appendages, and exoskeleton made of chitin. This phylum includes insects (e.g., butterflies, beetles), arachnids (e.g., spiders, scorpions), crustaceans (e.g., crabs, lobsters), and myriapods (e.g., centipedes, millipedes). Arthropods play essential ecological roles, such as pollinators, decomposers, and as part of the food web.
Tobacco Mosaic Virus: History, Importance , Structure and Symptoms
Tobacco Mosaic Virus (TMV) is a plant virus that mainly infects tobacco plants but can also affect other crops, including tomatoes and peppers. It is a rod-shaped virus, one of the first ever discovered and studied.
Phylum Annelida: Definition, Characteristics, Classification and Examples
Phylum Annelida (L., annelus = little ring or F., anneler = to arrange in rings) is a group of bilaterally symmetrical, coelomate, and segmented animals known commonly as segmented worms. Members of this phylum exhibit a body divided into repeated segments called metameres, which give them structural and functional division. Annelids are triploblastic and possess a true coelom, which is divided by septa, and a closed circulatory system. They have a complete digestive system, a well-developed nervous system with a ventral nerve cord, and excretory structures called nephridia. Respiration occurs through the body surface, gills, or parapodia.
Phylum Aschelminthes: Definition, Characteristics, Classification and Examples
Phylum Aschelminthes (Gr., askes = cavity ; helmins = worm) is a group of bilaterally symmetrical, unsegmented, and pseudocoelomate animals. They are typically characterized by a cylindrical or thread-like body covered with a tough, flexible cuticle. The phylum includes organisms that are predominantly aquatic or parasitic in nature, such as nematodes (roundworms).
Phylum Platyhelminthes: Definition, Characteristics, Classification and Examples
Phylum Platyhelminthes (Gr., platys = flat ; helmins = worms) refers to a group of invertebrate animals commonly known as flatworms. They are characterized by their soft, unsegmented, dorsoventrally flattened bodies. Members of this phylum are bilaterally symmetrical, triploblastic (having three embryonic germ layers), and acoelomate, meaning they lack a true body cavity. Platyhelminthes exhibit cephalization (a distinct head region) and possess a simple organ system level of organization.
Phylum Ctenophora: Definition, Characteristics, Classification and Examples
Phylum Ctenophora (Gr., kestos=comb; phoros=bearing) is a group of marine invertebrates commonly known as comb jellies. These organisms are characterized by their gelatinous bodies, biradial symmetry, and the presence of eight rows of ciliary plates (combs) that they use for locomotion. Unlike jellyfish, which belong to Phylum Cnidaria, ctenophores lack stinging cells (cnidocytes) and instead capture prey using sticky cells called colloblasts.
Viruses: Definition, Characteristics, Morphology and Classification
Viruses are intracellular obligate parasites, non-cellular (acellular) sub-microscopic organisms. The word “virus” means venom or poisonous fluid. They lack cell organelles and make use of the protein synthetic machinery of the host cell.