Banu's blog for school students

ORGANELLES IN A CELL   There are several structures scattered in cytoplasm of a cell. These are called as organelles which performs different functions in cell. Mitochondria is one such organelle which is very important as it is involved in respiration of a cell.  STRUCTURE OF MITOCHONDRIA  Mitochondria ( singular: mitochondria) are small, spherical or cylindrical organelles. The number of mitochondria in a cell depends upon the functions it performs. Cells with heavy energy demands, such as muscle cells, have more mitochondria than other cells. Generally a mitochondrion is 2-8 micron long and about 0.5 micron wide. It is about 150 times smaller than the nucleus. There are about 100 to 150 mitochondria in each cell.  When seen under the compound microscope ,the mitochondria appears oval or cylindrical dots in the cell.  When seen under the electron microscope, the mitochondria seems to have a double membrane wall. Their outer membrane is smooth whereaa inner mem...

The respiration which takes place in the absence of oxygen is called anaerobic respiration. Ex; yeast and some kinds of bacteria.  The end products of anaerobic respiration are : lactic acid and carbondioxide (with very little amount of heat ) in bacteria and  Ethyl alcohol and carbondioxide (with little amount of heat) in yeast.  When we make dough by adding yeast for making buns, pizza bases, bread etc we observe a peculiar smell of ethyl alcohol. Here yeast undergoes anaerobic respiration reacting with sugar in white flour and releasing carbondioxide gas which gets trapped in the dough due to which holes are formed in the dough.  DEMOSTRATING ANAEROBIC RESPIRATION IN THE LABORATORY we can demonstrate anaerobic respiration in the laboratory by a simple experiment. Let's see the complete activity.  LAB ACTIVITY  AIM: To  demonstrate anaerobic respiration in yeast  APPARATUS (MATERIALS)REQUIRED:  A thermometer, bent tube, small test tube and ...

Wastes includes all those items that people no longer have any use for ,which they either intend to get rid or have already discarded. Wastes are all those items that are required by law to be discarded. 'waste' is a much debated term, since what is waste to someone may be valuable to another. Nature fies not create waste, it is a fallout of our modern lifestyles. What needs no debate is ,waste has to be classified and understood to be able to manage. Waste management is vital to keep the environment unpolluted and  clean.  CLASSIFICATION OF WASTE Waste can be classified in different ways and this varies from country to country. Classification based on Physical state Waste can be solid ,liquid or gaseous. Liquid wastes  that are discharged into water bodies are called effluents, whereas wastes that are released into the atmosphere are referred to as emissions . The sources of such wastes could be municipal, domestic, agricultural or industrial. Gaseous emissio...

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 ...