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concept of species in zoology

 CONCEPT OF SPECIES It is already been stated that individual organisms which have many features in common and able to interbreed in natural conditions are encompassed by the term species. Species is the smallest basic unit of classification. Its proper characterization is, therefore, of vital importance for a 'Natural' scheme of classification. Identifying species on the basis of reproduction, John Ray (1693) considered all individuals produced by parents of the same types as members of the same species. Linnaeus and Some others distinguished species merely on the basis of structure. Morphological Concept of Species This is the most practical and widely used species concept to describe species since people began to classify organisms. Taxonomists use this concept mostly by default because they know most of the species on Earth only from their morphology. New species are usually named on the basis of morphological species concept; morphological descriptions are all that we need...
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biodegradable and non biodegradable wastes | Definition and difference between biodegradable and non biodegradable

Biodegradable and Non-Biodegradable Wastes

The material that becotablemes useless after being used and needs to be discarded is called waste. Everday, we generate a lot of waste through our activities. This waste can be domestic, municipal, agricultural, hospital or industrial. All the waste materials can be classified into two main categories.

1- Biodegradable wastes 
2- Non-biodegradable wastes

Biodegradable Wastes


biodegradable and non biodegradable wastes
biodegradable and non biodegradable wastes



The waste materials that can be broken down into simple harmless substances by biological processes are called biodegradable wastes. In biological processes, various microorganisms such as bacteria and fungi decompose biodegradable waste. These microorganisms release enzymes that act on waste and break it down into smaller harmless substances. All the enzymes are specific in their action and they can only break down the natural materials or the products made from natural materials. Enzymes cannot breakdown various human made materials like plastic. Examples of biodegradable waste is include cow dung, vegetable and fruit peels, cotton, jute, paper, wool, Tea leaves, leather, animal products and Agricultural Products.

Effects of biodegradable wastes:

1- Decomposition of biodegradable substances produces foul smell that pollutes the surrounding environment.

2- Disease carrying gems breed on garbage heaps and spread diseases like typhoid, diarrhoea and cholera.

3- Sometimes, heavy rainfall washes away the waste to the water sources and makes it unfit for use.

Non-Biodegradable Wastes 


biodegradable and non biodegradable wastes
biodegradable and non biodegradable wastes


The waste materials that cannot be broken down into harmless substances by natural biological processes are called non-biodegradable wastes. The non-biodegradable wastes include many man made materials like plastics, polythene bags, synthetic fibres, ballpoint pen refills, glass items, aluminium cans, radioactive wastes, DDT, mercury and lead. All these non-biodegradable wastes cannot be broken down by the action of bacteria or other a
saprophytes and hence they are major pollutants of the environment. DDT (Dichlorodiphenyltrichloroethane) is a non- biodegradable waste which can enter the food chain from crops to humans and cause serious health problems. Because of this reason, use of DDT as a pesticide is banned in most of the countries.

Effects of non-biodegradable wastes:


1- These waste substances enter the food chain through crop-fields and cause several health problems in living organisms. 

2- The harmful chemicals and pesticides seep into the soil and contaminate groundwater sources.

3- Dumping of industrial waste on open fields pollutes soil, thus reducing its fertility. 

Differences between Biodegradable and Non-Biodegradable Wastes 


Biodegradable Wastes


1- They originate from biological matter.
2- They can be decomposed by microorganisms. 
3- They do not pollute the environment. 
4- After decomposition, they form compost or biogas.
5- Examples: Paper, cotton, jute items, wood, cattle dung.

Non-Biodegradable Wastes


1- They are artificial or man-made. 
2- They cannot be decomposed by microorganisms. 
3- They pollute the environment. 
4- They cannot be decomposed, but they can be recycled to form new products. 
5- Examples: Plastics, polythene bags, metals, glass, mercury. 





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