Banu's blog for school students

Bio magnification is a process by which some pollutants fail to degrade inside the bodies of animals , remaining unchanged and becoming concentrated in successive trophic levels in food chain or food web. When chemicals obtained as part of food fail to degrade( eg.mercury) or degrade slowly ( eg DDT), they remain accumulated in the body tissues. When plant tissues accumulate such substances, they get passed on to the animals eating them. The small amounts of these chemicals from different plants add up and accumulate in higher quantities in animal tissues. These animals are then inturn eaten by other animals, where the chemicals get further concentrated. This process of increasing concentration of chemicals in organisms at the higher levels of a food chain is called biomagnification . The higher an organism is in the food chain, the greater the concentration of chemicals.  A classic example of biomagnification is Minimata disease, which affected the fisher folk of Minimata Bay ,Jap...

When water bodies such as lakes, estuaries and slow moving streams receive excess nutrients ,it results in excessive plant (algal) growth . This process is called eutrophication. This excessive growth of plants such as  Water hyacinth and algae reduces the dissolved oxygen (BOD- biological oxygen demand) in water. The water body then becomes incapable of supporting fishes and  other forms of aquatic life. Excessive growth of algae in such water bodies is described as algal bloom. Nitrates and phosphates are the two main substances(nutrients) that causes such condition, which is a direct result of pollution. These nutrients come from a variety of sources,such as fertilizers applied to agricultural fields and golf courses, excessive use if detergents, erosion of soil containing nutrients,untreated sewage and discharges from sewage treatment plants. EUTROPHICATION not only leads to reduced oxygen but also produce foul odour and slow death of water body. Thus, biodiver...

Anything obtained from the natural environment to meet our needs or is important for our survival is a natural resource. Thus, air,water,and soil are necessary for survival; whereas metals,other minerals (including fuels),and forests serve to meet our needs. These are all examples of natural resources. Technological advancements has enabled us to keep adding to  this of resources to support our changing lifestyles. These can be called as human made resources. Plastics, optic fibres and synthetic fibres are examples of such resources. AIR Air is a mixture of gases constituting mainly of nitrogen and oxygen and to a smaller extent carbon dioxide,noble gases,a small percentage of water vapour and traces of other gases. Their respective composition are: Nitrogen: 78.084% Oxygen: 20.947% Carbon dioxide: 0.033% Argon: 0.934%  Air is very essential for our survival. When we say this, we often refer to oxygen but even other gases are also of equal importance. About 75% of the earth's ...

The circulatory system or the transport system consists of heart, blood and blood vessels.  The heart is the main pumping organ of a body which functions continously without stopping for a second. It is made of cardiac muscle whose contraction and relaxation makes a  pulse rate or a heart beat .  Blood is a red colour fluid freely floating in our body to supply food, nutrients and oxygen to each and every cell and also collecting waste materials from them . Blood vessels are the closed tubes through which the blood is circulated in our body.   Structure of heart  The heart is a conical structure which lies slightly left in the chest or thoracic cavity. It's anterior end is broader while posterior end is narrower in shape . It is the size of one's fist. It is covered by two membranes called pericardial membranes. The space between these pericardial membranes is filled with a fluid called pericardial fluid which protects the heart from shocks. Internally heart is ...