General Science
In the present times, the laws and principles of science find application, not only in our daily life but also in every walk of life. As a result Science and Technology have become an integral part of human life and culture. Scientific knowledge which is growing day by day is a powerful tool for solving our problems.
Atom and Atomic Mass
An atom is the smallest particle of an element that retains its (elements) chemical properties. An atom of one element is different in size and mass from the atoms of the other elements. These atoms were considered "indivisible" by Indian and Greek Philosophers in the beginning and the name "atom" emerged out of this basic philosophy.
Dalton's Atomic Theory
The English scientist John Dalton was by no means the first person to propose the existence of atoms. Such ideas date back to classical times. Dalton’s major contribution was to arrange those ideas in proper order and give evidence for the existence of atoms.
Law of Chemical Combinations
There was tremendous progress in Chemical Sciences after 18th century. It arose out of an interest in the nature of heat and the way things burn. Major progress was made through the careful use of chemical balance to determine the change in mass that occurs in chemical reactions.
Separation of Mixtures
To separate different components of a mixture variety of physical techniques are available. All these separation techniques are based on difference in the physical properties of the components present in the mixture.
Suspensions
In winter, the fog is a common experience in both urban and rural areas. Fog forms when tiny water droplets are suspended in air. So, fog is nothing but a type of a suspension. There are large numbers of substances which do not mix with each other.
Solution and its Concentration
A solution (a homogeneous mixture) is formed when one or more substances (the solute) are completely dissolved in another substance (the solvent). The most common examples are the solutions that are obtained by dissolving solids in water.
Disorders Related to Circulatory System
Heart attack, Anemia, Leukemia, and Hypertension are disorders related to the circulatory system.
Blood Group
Blood has to be arranged for a person undergoing a surgery (operation) or in the case of an accident or in case of persons suffering from thallasemia. This arrangement is to replace blood lost from the patient.
Blood
Blood is a connective tissue that circulates throughout the body. It is made up of a fluid medium called plasma in which float two types of blood cells, called red blood cells, white blood cells and cell fragments called blood platelets. Blood cells are manufactured in the bone marrow.
Transportation in Humans
Human circulatory system consists of centrally located muscular pump called heart, circulating fluid (blood, tissue fluid and lymph) and blood vessels, which are tube-like structures, connected to the heart.
Life Processes
The activities by which living organisms take in food, derive energy, remove waste from their body and respond to changes in the environment are called life processes.
Deficiency Diseases or Nutritional Disorder
A disease that occurs due to lack of adequate and balanced diet is called deficiency disease. Intake of improper or inadequate diet in human beings is called malnutrition. Malnutrition is harmful for children as it retards their mental and physical growth.
Digestion - Nutrition in Human Beings
The food that we eat cannot be used by the cells in the body in the form in which it is eaten. Conversion of complex food material into smaller substances so that it can be absorbed by the cells is called digestion. Taking in of food is termed ingestion.
Nutrition in Humans
For healthy growth and development of the body, you need to eat food that provides enough of all essential nutrients. Nutrients are the chemical substances present in the food which nourish the body.
Nutrition in Plants - Photosynthesis
Green plants synthesize their food themselves by the process of photosynthesis. Photosynthesis is a biochemical process by which green plants manufacture their own food using carbon dioxide and water as raw materials in the presence of sunlight and chlorophyll. Oxygen is released as a by-product in this process.
Types of Nutrition
Nutrition is defined as a process by which living beings obtain food, change food into simple absorbable forms and use it to make substances needed by the body.
Why Do We Need Food
Living beings need food to survive. Food provides the essential raw material that the body needs to grow and stay healthy. It also provides energy to carry out various life processes.
Heterogeneous Mixture
Mixtures where the constituents do not completely mix with each other, and remain separate, are called heterogeneous mixtures. In such mixtures, one substance is spread throughout the other in the form of small particles, droplets or bubbles.
Homogeneous Mixture
In some mixtures, constituents are completely mixed in such a way that the entire mixture has the same composition throughout. Such mixtures which have uniform composition are called homogeneous mixtures.
Elements, Compounds and Mixtures
Matter can be classified on the basis of its composition as element, compound or mixture.
Effect of Temperature and Pressure on States of Matter
When heat is supplied to a solid, it expands. This expansion is very small. In fact, after receiving thermal energy, particles (atom or molecules) vibrate more rapidly in their position and take up more space. If particles become more energetic on further heating they leave their fixed positions and the solid melts.
Stem Cell Technology
Stem cells are undifferentiated (unspecialized) cells in our body which have the capacity to undergo mitosis and differentiate into specialized cell types and can redivide to produce more stem cells. Stem cells may be obtained from an embryo, the umbilical cord and bone marrow in adults.
Animal Tissue
Animal tissues are grouped under four main categories: epithelial, connective, muscular and nervous tissues.
Tissues
Various tissues of an organism work in co-ordination with each other in order to perform different processes that occur in the body.
Cell Division
New cells are required for replacement of worn out cells, for repair of cuts and injuries, and for growth and for reproduction. New cells are obtained through cell division.
Cell Structure and Functions
Cells within the body of a multi-cellular organism differ in shape, size and function, but have three basic parts - cell membrane, cytoplasm and nucleus.
Prokaryotic are Eukaryotic Cells
A cell is the structural and functional unit of all living beings. All cells have three basic parts.
Cell Theory
When a small wall is built, a number of bricks are arranged end to end. Similarly cells are arranged variously to build the bodies of living beings. In fact, every organism begins life as a single cell which is the fertilized egg. Cells divide to give more cells. Cells form tissues. Tissues make organs.
Human Evolution
All the different life forms that we see on earth now evolved only gradually. Radiometric dating of geological (earth) strata and detailed study of the fossils found in them help us in reading important chapters in the history of life on earth since its origin 4.5 billion years ago.
Neo-Darwinism
Although Darwin talked about heritable variation, he did not know exactly how heritable characters arose and were passed on from one generation to another. This is because Darwin was not aware of the principles of genetics developed by Mendel a few years before the publication of his book "Origin of Species".
Darwin’s Theory of Evolution
Darwin made important observations and drew inferences from them, which helped him in developing his theory of evolution.
Diversification of Life
Life on earth started in the form of simplest unicellular (prokaryotic) microorganisms. In course of time, these organisms evolved to utilize solar energy through chemical process called photosynthesis. It is through the photosynthetic activity of the earliest autotrophs that oxygen built up gradually in the earth’s atmosphere making it possible for complex heterotrophic organisms to evolve.
History of Life
The universe around us is so enormous that it is difficult even to imagine its dimensions. In a far corner of the Milky Way Galaxy, (one of the billions of galaxies comprising the universe), sits our solar system. Within this system, Earth, the planet on which we live, is one of the planets revolving around the Sun.
Animalia Kingdom
Kingdom Animalia is grouped into non chordates which are further divided into the phyla Porifera, Cnidaria, Platyheminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, and Echinodermata.
Plantae Kingdom
Kingdom Plantae has five divisions namely Algae, Bryophyta, Pteridophyta, and Spermatophyta. Spermatophyta further divided into Gymnospermia and Angiospermia or flowering plants.
Five Kingdoms of Life
Earlier there were only two kingdoms of plants and animals. Whittaker in 1969 suggested that bacteria should not be in plant kingdom and protozoa not in animal kingdom. He gave the five kingdom classification.
How Organisms are Named
Every organism has a scientific name beside the name by which it is known in a particular language. For example, mango is its name in English, Aam in Hindi and Mangifera indica, its scientific name. In scientific naming, genus and species of the organism are mentioned. For example, Homo sapiens.
States of Matter
Matter can ordinarily exist in three states - solid, liquid and gas. These three states of matter have different properties. Water exists in all the three states namely steam or water vapour (gas), water at room temperature (liquid) and ice (solid). This is the only substance which exists naturally in all the three states.
Matter in Our Surroundings
Anything which occupies space and has mass is matter. All solids, liquids and gases around us are made of matter. Scientist believe that matter is made of tiny particles that clump together. You cannot see these particles but you can see the matter, for example, a book, a car, a letter, a hand set, a piece of wood, tree, a bag.
Definitions of Seven SI Units
The International System of Units, called SI units, is based on seven base units which correspond to seven base physical quantities namely length, mass, time, temperature, amount of substances, light intensity and electric current.
Derived Units
The base or fundamental SI units like length, mass, time are independent of each other. The SI units for all other physical quantities such as area, density, velocity can be derived in terms of the base SI units and are called derived units.
SI Units
An international system of units, called SI units, was adopted at the 11th General Conference on Weights and Measures (CGPM) in 1960. SI is an abbreviation of the French name - Le Systeme Internationale de Unite’s.
How Did Ancestors Make Measurements
The need for measurement and measuring devices dates back to antiquity. When the humans became civilised, started cultivating and living in communities they realised that one cannot do everything and they need to be interdependent. This paved the way for trade and then probably a need of a measure was felt.
Measurements
Measurement is a basic skill which forms an essential part of day to day activities. Measurement is defines as a counting of the number of times a chosen scale is used.
Classification of Organisms
Grouping of organism according to similarities and differences is termed classification. When an organism is classified into various categories, a hierarchy is maintained. Accordingly, an organism belongs to Kingdom, Phylum, Class, Order, Family, Genus and Species in hierarchical order.
Patterns of Biodiversity
The entire world is divided into six biogeographic regions. The organisms found in these regions are adapted to the climate of these regions. Certain kinds of organisms are common to all regions while some are restricted to certain regions only.
Levels of Biodiversity
All the varieties of living organisms on earth constitute biodiversity. Three levels of biodiversity have been recognized.
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