Muscle is a specialized tissue of mesodermal origin. About 40-50 percent of the body weight of a human adult is contributed by muscles. They are formed by specialized elongated cells called muscle fibres or myofilaments. They have special properties like electric excitability, contractility, extensibility, and elasticity. Contractility is due to the presence of myofibrils formed by highly […]
Typhoid is a bacterial infection that can lead to high fever, diarrhea, and vomiting. If typhoid is diagnosed early, it can be successfully treated with antibiotics; if it is not treated, typhoid can be fatal. The name typhoid is given to the disease by Louis in 1829, as a derivative from typhus. Typhoid fever has received […]
The planet earth came into existence sometime between 4 and 5 billion years ago. Life evolved on planet earth about 3.5 billion years ago. The origin of life on the earth is also called photobiogenesis. Now it is clear that the life came into existence from the non-living substances. Theory of Special Creation of Origin of […]
Techniques, Procedures, and Stored Information that are useful in the identification and classification of organisms are called taxonomic aids. Herbaria, botanical gardens, museums, zoological parks (zoos) are important taxonomic aids used in the identification of plants and animals. Taxonomic aids are required because the taxonomic study of plants, animals, and other organisms is basic to almost […]
In this article, we shall study the female reproductive system in humans. Human Reproductive System: Puberty means the changes that occur in boys and girls as they grow up. In this period the maturity of human sex organs begins. Most of these changes occur between the ages of 10 to 14 years. These changes are brought about by […]
In this article, we shall study sexual reproduction and the male reproductive system in humans. The process of formation of life from pre-existing life is called reproduction. In animals two types of reproduction are observed a) asexual reproduction and b) sexual reproduction. Asexual Reproduction: A mode of reproduction in which the offspring comes from a single […]
The Earth has formed 4.5 billion years ago and on the Earth, which arose the first life form in the form of Prokaryotic cells. These unicellular creatures are primordial and are building blocks of multicellular organisms. Life is supposed to have originated from the oceans which is why embryos of terrestrial and aerial animals still […]
The living organisms which cannot be seen with the naked eyes (unaided eyes) and can only be observed through a microscope are called microorganisms or microbes. The branch of science that deals with the study of microorganisms is known as microbiology. Microorganisms may be single-celled like bacteria, some algae, and protozoa, or multicellular, such as algae and […]
Amino acids contain an amino (–NH2) and carboxyl (–COOH) functional groups. The amino acids in proteins are called alpha (α)-amino acids because the amino group is attached to the α-carbon. A carbon directly connected to carbonyl carbon is termed α-carbon. Depending upon the relative position of the amino group with respect to the carboxyl group, the amino acids can be […]
Unicellular organisms are capable of having an independent existence and of performing the essential functions (metabolic activities) of life. Anything less than a complete structure of a cell does not ensure independent living. Hence, the cell is the fundamental structural and functional unit of all living organisms. All the living organisms, from the smallest (unicellular) to the […]