The Big Bang theory is the most accepted scientific theory which explains the origin of the universe. It states that the universe was formed by expansion of an extremely hot and dense singularity about 13.8 billion years ago. It is…
The Big Bang theory is the most widely accepted scientific theory for the origin of universe. It states that the universe came into existence 13.8 billion years ago by rapid expansion of an infinitely dense and hot point containing all…
Hormones regulate target cells by binding to specific protein receptors. Their mechanism of action depends on whether they are lipid soluble or water soluble. MECHANISM OF HORMONE ACTION Hormones exert their action through receptors. These receptors are present on target…
Hormones are chemical substances secreted by ductless glands (endocrine glands) that are released directly into the circulation in small amounts in response to a specific stimulus and causes response on the target cells or organs. Hormones interact with their target…
Soil erosion is the removal of fertile top layer of soil by wind, rain and water. Soil erosion leads to loss of fertility of land and makes it unsuitable for farming. Soil is one of the most valuable natural resources…
The cerebral cortex is the outermost layer of gray matter of brain. It regulates higher level functions like memory, thinking, language and sensory processing. It is called as the “seat of consciousness“. It is folded into gyri (elevated ridges) and…
Minerals are essential inorganic elements required by the body in small quantities to perform normal functions related to growth and development. Dietary minerals are divided into two categories : Macrominerals (required in larger amounts) and trace minerals (required in very…
Vitamins are essential organic micronutrients required by body in small quantities to support metabolism, immunity and growth. They are not manufactured in body in sufficient amounts, therefore, they have to be supplemented through diet. Vitamins can be classified into two…
The cranial nerves are those nerves which emerge directly from the brain and brainstem. There are twelve pairs of cranial nerves. They serve as crucial links between the brain and various parts of the body, primarily head and neck regions.…
Asteroids and comets are rocky and icy remains of formation of our solar system formed around 4.6 billion years ago. The ice and dust particles came together due to gravity and slowly grew in size. Asteroids are rocky or metallic…
The water cycle is the cyclical process by which water circulates between the earth and its atmosphere in a series of stages where water undergoes change of state from liquid to vapor and back to liquid. Water cycle is also…
MITOSIS Mitosis is a type of cell division by which a cell divides into two identical daughter cells. It occurs in all somatic cells. Mitosis produces diploid cells with two sets of chromosomes . Mitosis occurs in four phases –…
The cell cycle is an ordered process during which a eukaryotic cell undergoes cell growth, DNA replication and finally divides into two identical daughter cells. All organisms begin their life from a single cell. The cell cycle allows formation of…
Translation is the process of synthesizing protein using mRNA as template. It takes place in cytoplasm of cell. It is the mechanism which enables gene expression. Translation is the second step in genetic expression. The mRNA produced by transcription from…
Transcription is the process by which a specific segment of DNA is copied into RNA. This occurs by utilizing an enzyme called RNA polymerase. In eukaryotic cell, transcription takes place in nucleus whereas in prokaryotes, it takes place in cytoplasm.…
DNA replication is the process by which two identical copies of DNA are produced from parent DNA molecule before the cell divides so that each daughter cell gets a complete set of DNA after cell division. It is semi-conservative in…
RNA (ribonucleic acid) is a single-stranded nucleic acid present in cell of all living organisms and some viruses. It plays important role in protein synthesis and gene regulation. RNA is a polymer made of single chain of nucleotides. A nucleotide…
A neuron is a specialized cell that receives, processes and transmits information throughout the body by utilizing electrical and chemical signals. They receive sensory stimulus from environment, process it and send motor commands to muscles. Neuron is the structural and…
The cerebellum of brain is located in the posterior cranial fossa behind pons and medulla oblongata. It is the largest part of hindbrain. A tent shaped fold of duramater called tentorium cerebelli forms roof of cerebellum. Cerebellum consists of a…
The ventricles of brain are interconnected cavities within brain containing cerebrospinal fluid. There are four ventricles in brain : The lateral ventricles communicate with the third ventricle through interventricular foramina of Monro. The third ventricle communicates with fourth ventricle through…
Genes and alleles form the basis of heredity. A gene is the sequence of nucleotide on DNA which makes protein. An allele is is the variant form of a specific gene that regulates a trait. For example, for a gene…
A chromosome is a structure made by condensation of DNA found in nucleus of a cell that carries genetic material of an organism. The DNA of a eukaryotic organism gets highly condensed within the nucleus of cell to form chromosome.…
Iron is a trace element which is required for a number of vital functions in the body. Iron absorption occurs in the small intestine. Iron from plant based diet is in the ferric form ( Fe3+) called non – heme…
The brain which incorporates about 86 million neurons is an important component of our nervous system. The nervous system controls, coordinates and regulates all voluntary and involuntary functions of body by making use of electrical and chemical signals after sensing…
DEFINITION OF ANEMIA Anemia is a disease in which there is reduction in the number of red blood cells less than 4 million/microliter or decrease in the amount of hemoglobin less than 12gm/dL or both. The deficiency of hemoglobin results…
Whether the universe is expanding or is static was not known before the twentieth century. The belief in a static universe was strong till that time. According to the most widely accepted theory for the origin of our universe, the…
Growing population, increasing energy demands and depleting energy resources along with emission of pollutants associated with conventional energy sources have necessitated search for a novel healthier and reusable energy resource that can meet increasing energy requirements as well as conserve…
It is the presence of cell that differentiates the living from non-living. Cell is thus rightly known as the basic unit of life. DEFINITION OF CELL – Cell is the fundamental structural, functional and biological unit of all living organisms.…
One of the greatest scientific accomplishment of the 20th century has been the discovery of DNA (deoxyribonucleic acid) – the polymeric molecule which encodes the genetic data across its length. It forms the chemical basis of heredity capable of organizing…
WHAT IS GREENHOUSE EFFECT Greenhouse effect is a natural process by which the Earth’s atmosphere retains some of the heat of Sun, thereby maintaining adequate warmth for survival of life. The Sun sends electromagnetic radiation to Earth from an enormous…
Did you know that plants can make their own food? Yes – plants and even algae, cyanobacteria, kelp and phytoplankton can do so by a process called photosynthesis. Photo – light (Greek); Synthesis – putting together (Greek). This takes place…
The eight planets, moons, dwarf planets, asteroids, comets all centered around the sun make up the “solar system”. It was formed 4.5 billion years ago. Located in the Milky Way’s Orion star cluster, the solar system derives its name from…
