PLANT KINGDOM

Many kinds of plants are found in this world. Some of them are large and some are small. Few are so small that cannot be seen without microscope. Plants are divided into two major groups on basis of structure and other characters.

  1.FLOWERING PLANTS

   2.NON- FLOWERING PLANTS    

1.4 BACTERIA

1.3 BACTERIA

Bacteria are found in everywhere, in , air, water, living and dead bodies of organisms and even in glaciers and hot springs. On basis of shape and form, bacteria are of four types, round ,rod-shaped, spiral and comma shaped.

  Bacteria are found singly or in groups and even in beaded form. Bacteria are unicellular microscopic organisms. A distinct nucleus is absent in bacteria , however , only a single large , circular molecule of DNA is present. This is not bounded by nuclear membrane. Bacterial cell is surrounded by a cell wall. A few bacteria have an additional slime capsule around their cell wall. Some bacteria have one or more thread like flagella (Singular flagellum), which help them in locomotion.

Some bacteria are autotrophs while majority of them are heterotrophs. Bacteria, which live on other living organisms for their nutrition, are called parasitic bacteria. The parasitic bacteria cause diseases in plants and animals and are known as pathogenic bacteria. Bacteria are transmitted from one living organisms to another through touch, air, contaminated water and food, insects and other animals.

Importance of bacteria  :

  Bacteria play an important role in our lives. They are beneficial as well as harmful to us

Advantages:

 Bacteria act as decomposers. They decompose dead bodies of plants and animals so increase soil fertility. Some bacteria add nitrogenous compounds in soil, thus maintain its fertility.

    Bacteria are used for industrial and commercial purposes such as in manufacturing butter, cheese and yogurt in processing of vinegar, tobacco , coffee and leather.

Antibiotics such as streptomycin, tetracycline and terramycin are obtained from bacteria. These antibiotics destroy harmful bacteria.

Disadvantages:

 Food is decomposed and putrefied by bacteria.

THINK ABOUT!

  Many bacteria are harmful and cause many diseases in plants, animals and human beings. Canker disease in citrus fruits (lemon and orange) ; fire blight in peach, pear, apple and scab in potatoes are caused by bacteria.

What would happen, if there were no bacteria in this  world???

   In animals like cattle, bacteria are responsible for T.B. and Anthrax. Bacteria also caused diseases in man like T.B., whooping cough, diphtheria, typhoid, pneumonia, tetanus, plague, cholera, leprosy and anthrax.

1.3 VIRUSES

1.3 VIRUSES

  Viruses are so small that they cannot be observed with light microscope but can be studied with electron microscope and biochemical tests. 

VIRUS IS A LATIN WORD WHICH MEANS POISON

Viruses are of different shapes, some are rounded, few are rod-shaped and a few polyhedral while some viruses look like tadpoles.

              Structurally viruses are made up of nucleic acid and proteins. Viruses consist of two parts, an outer ‘coat’ and inner ‘core’. The coat is composed of protein and the core is made up of DNA or RNA.

  Viruses are considered as a link between living and non-living things. They reproduce like living organisms and non-living organisms, found also in the form of crystals.

     All viruses are parasites and obtain their food from other living organisms. Viruses in living organisms are transmitted in variety of ways i.e. by air, contaminated water and food, through insects, droplets produce on coughing and sneezing and through contact.

Viruses produce many diseases in plants and animals. In human beings, viruses produce Measles, Influenza, Cold, Small pox, Polio, Hepatitis B & C, Cancer, AIDS and SARS. Viruses usually cause diseases in the plants of tobacoo, potato, tomato and cabbage etc.

DO YOU KNOW?

SARS (Severe Acute Respiratory Syndrome) It is a pneumonia like viral disease, in which at first temperature of patient rises. He feels cold, irritation in throat, difficulty in breathing and suffocation. Some times death can occur.

  

Diagrams of Micro-organisms F.G 1.1

s

1.2 Micro-organisms:

   Micro means small and organisms means living things. Micro-organisms are those organisms that are so small and they cannot be seen with naked eye. In order to observe them, we need a light microscope or an electron microscope.

      Micro-organisms form a diverse group which includes different types of organisms, viruses, bacteria, unicellular plants and animals, certain algae and fungi (Fig1.1)

Micro-organisms differ from one another with regard to structure and mode of nutrition. On the basis of structure viruses are not cellular while other micro-organisms are cellular. Bacteria are unicellular but they have no organized nucleus while other micro-organisms have organized nucleus. According to mode of nutrition algae and few bacteria are autotrophs while fungi and most unicellular animals are heterotrophs. Due to these characteristics micro-organisms form a diverse group which includes different types of organisms. 

CLASSIFICATION OF LIVING ORGANISMS 1.1 CLASSIFICATION:

CLASSIFICATION OF LIVING ORGANISMS

1.1 CLASSIFICATION:

           Thousands of living organisms are found in this world.Some of them are large and some are small.Among them some resemble to each other in shape and form and many are distinctly different from one another.Living organisms are arranged in different groups due to their differences and similarities.This grouping is called Classification.In this grouping organisms are placed into different units are given technical names.The basic unit of classification is Species.A species can be defined as,a group of closely resembling organisms that can interbreed in nature but are not able to sexually reproduce with individuals of other species; for example cat and rabbit are two species.All cats belong to one species and all rabbits belong to another species.All individuals of one species are different from the individuals of other species and cannot reproduce with them in nature.It is necessary for study of living organisms to classify them in different groups.It is easy to study organisms on the basis of classification.Classification of living organisms tell us interrelationship among them and very closely resembling individuals are placed in the same group and distinctly different individuals are grouped in different groups.In this way,organisms are identified on the basis of their structures and other characteristics.So we can study then systematically and logically.