(Author of this  article: Shakila Mahbuba Chowa) From the previous  topic, we learned about test of significance, a procedure for comparing observed data with a claim or hypothesis or predicted data. This test of significant is used to test e claim about an unknown population and for testing the research …

Author: Tahmina Mojumder This article discusses Recombinant  DNA  and  gene cloning, plasmid  and  phase vectors, restriction enzymes, restriction maps and their properties, recombinant selection. Recombinant DNA Recombinant DNA is the common name  for a segment of  DNA  that has been created by combining at least two  fragments from two different …

Soil is defined differently by soil scientists, and its definition has changed overtime. Since the year 1800, there have been more than 80 different definitions of soil available in literature. Generally, soil can be defined as the organic and inorganic materials on the surface of the earth that provide the …

Water: Water is a transparent and nearly colorless chemical substance that is the main constitute of Earth’s streams, lakes, oceans and the fluids of most living organisms. Resource: A resource is any physical material constituting part of Earth that people need and have value. Natural materials become resource when humans …

The term ‘ecosystem’ was first used by A. G. Tansley in 1935. Tansley defined ecosystem as ‘a particular category of physical systems, consisting of organisms and inorganic components in a relatively stable equilibrium, open and of various sizes and kinds‘. An ecosystem is a structural and functional unit of the …

Global Radiation Balance There are various factors that influence the amount of radiation coming from the sun to the earth’s surface. Some of the radiation is reflected upward, some is scattered both upward and downward directions. Besides, some of the radiation is absorbed by the clouds and atmosphere. The rest …

Arsenic is a naturally found chemical element whose atomic number is 33 with a symbol as ‘As’. It occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is one of the fundamental chemical element. It is a metalloid. Symbol: As …

Toxicity is the degree to which a substance can damage an organism. Toxicity can affect a whole organism, such as an animal, bacterium, or plant, as well as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). Toxicity effects are dose-dependent; so, even water can lead to water …

The marine environment is an essential component of the global life-support system. Marine environment is different from the terrestrial and freshwater aquatic environment having high salt concentration. Its water covers approximately 71% of the earth’s surface. This is equivalent to 361 million sq. kilometers (139 million sq. miles). Average depth of …

Photosynthesis is a chemical reaction that takes place inside a plant, producing sugar type food for the plant to survive. Carbon dioxide, water and light are all needed for photosynthesis to take place. It happens in the leaves of a plant and the other green portions as well. The process of photosynthesis …