Biology

Introduction To Biology


Importance of Studying Biology


1. To get an idea about the importance of biodiversity


  •  The life began on earth 3.5 million years ago. So there are about 30 million species of plants and animals on earth. The biodiversity play a major role in maintaining the environmental balance.
  • The living component has a dynamic relationship with the non living component. Then there is a slight change in the non living component a large impact will be created on the living component.
Eg :- 85% of sunlight is converted to heat energy and most of this heat energy is absorbed by plants for transpiration. There by this process reduce the temperature of the earth surface, and maintain the temperature at an optimum level.
But due to deforestation and environmental pollution the transpiration process will be affected. Therefore the accumulation of heat on earth will be more and cause the global warming. Therefore the glaciers melt resulting the increment of sea level. So sea erosion takes place and low level islands sink and due to this reduction in transpiration reduce the formation of clouds and cause the bad impacts on water cycle and also climate changes.Due to this seasonal cultivation affects. So everything on earth get affected due to small change in the environment.
By studying biology you get to know that the importance of conserving forests which means conserving of bio diversity.


2. To get the knowledge about the anatomy and physiology of the human body.


  • By having an idea about the structure, organization and interactions among organ systems people would get a clear idea about how to maintain a healthy body and how much it is important to maintain good health habits for a healthy life.
3.  Management of natural resources and the environment.
  • As natural resources are limited people should consume them in a sustainable manner and they should be aware of the importance of renewable sources than non renewable.
Example:  To limit the fossil fuel combustion
                 To reduce the use of CFC
                 To control the environmental pollution by using biodegradable materials

4. Sustainable food production.
  • The world population is about 6 billion. According to the latest research there are tree new born babies added to the world population in every second. It’s a very high population growth rate.
  • Therefore to supply food for the demand of this high population would be problem. Therefore have to improve agricultural technology like,
    1. Produce high productive plant and animal varieties.
    2. To produce resistant plant and animal species for diseases.
    3. Has to introduce improved cultivating methods.
    4. New technologies in propagation of plants and animals.
      • Tissue culture
      • Genetic Recombinant technology
      • Hydroponics 



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5. To get a knowledge about the diseases and the preventive measures of some diseases.
  • To produce artificial vaccines (BCG)
  • To take preventive measures for the disease like AIDS, Hepatitis & TB
  • To give first aid in accidents
  • To birth control
  • To develop treatments for diseases like AIDS, Cancers etc.
  • To prevent genetically transmitting diseases, thalacemia and hemophilia
  • To produce medicines like antibiotics.

6. Use the knowledge of biology in industries.
    1. Curd and Yogurt industry – Lactobacillus.
    2. Vinegar industry – Acetobacter Aceti
    3. Bakery industry, vine, beer – Saccharomyces

Nature and organizational patterns of living world.

Nature of the organisms
  • They show a vast range of diversity by the size, shape, form & distribution.



Size
  • Bacteria is about 0.2 µm in size and a plant like red wood is about 100m in height.



Shape
  • The animal and plants and bacteria and protists have different shapes.



Examples : Bacteria
·         Bacillus
·         Coccus
·         Sprillum
·         Vibrio

Forms
  • A-Cellular (virus)
  • Unicellular (amoeba)
  • Multicellular



Distribution
  • Terrestrial
  • Aquatic (marine & fresh water)
  • Aerial
  • Arborial 

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Characteristics of living beings

1. Order and organization
  • All living things are highly ordered. They are made up of a single cell or many cells. Cell is the structural and functions unit of the living beings. Lives order and organization of matter ranging from subatomic particles to biosphere.
Subatomic particle --à Atoms --à Molecule --à Organelle -à Cell--à Tissue  --à Organ System --à Organism --à Population --à Community--à Eco system --à Biosphere

2. Metabolism
  • All chemical reactions take place within the cell body is known as metabolism. Metabolism is of two types.
    1. Anabolism – Synthesis of complex compounds using simple substances. Example : Photosynthesis , Protein synthesis
    2. Catabolism – Breaking down of complex compounds into simpler substances.    
Example : Respiration , Digestion 

3. Growth and Development
  • Irreversible increase of DRY mass is known as the growth.
  • The construction of the form of the body of an organism from birth to maturity according to an identical pattern to that particular organism is known as the development.
  • It is an orderly development and unfolding of structure and activities that allow organisms to cooperate successfully with their environment.
  • Example : A multicellular organism starts its life as a single cell and develop into an individual containing many multicellular organs which acquired specific function 
4. Irritability and Coordination
  • The ability to respond towards the stimuli from the environment is referred to as IRRITABILITY. For the responses to take place, there are effector organs and for the stimuli to detect there are receptor organs.
  • The communication between the receptor organ and the effector organ to respond to a particular stimulus is referred to as the coordination.
  • Example : Growth of the tip of the shoot system of a plant towards the sunlight. 
5. Adaptation
  • Particular innovation of structure and the function which helps living things to maintain life by extracting energy and materials form the environment and to reproduce - SURVIVAL.
  • To survive, an organism must be specifically suited to its environment and the way of life.
  • Examples : Presence of sunken stomata (Thick cuticle), Presence of bristles on the leaf surface in plants which grow in ARID zones, Presence of webbed feet of frogs. 

6. Reproduction
  • Living beings are not immortal. Sooner or later everything dies. The continuity of life on earth occurs because of the ability to reproduce which give rise to a new offspring of the same kind.
  • The offspring get the parental genetic materials which determine its characteristic features. Except virus all the living beings genetic materials are DNA.

7. Heredity and Evolution
  •   Living things have genes or units of heritable information that pass from one generation to the next which control specific, physical, chemical & behavioral activities within that organism. This is known as the HEREDITY.
  •    Living things change over time (slow) according to the environment. This is evidence from fossil records of early organisms. All living things descend from a common ancestor and arose as a result of genetic modifications (MUTATION) of species over the time. This process is referred to as EVOLUTION.
  •    During evolution, the organisms with most suitable adaptations will remain in the environment and the organisms with unfavorable adaptations have to be wiped out (extinct) from the earth.
Example: - Dinosaurs 


Many of non-living entities have one or more of these characteristics. But not all of them.

Example: - Crystal's growth, Movement of waves



But only living beings display all these characteristics simultaneously or at some instances during their life time.


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Scientific Method
    Explanation
  • This is the standard sequence of steps normally followed by the scientists or biologists all over the world in investigating particular event or a problem. This at be a problem in biology or any other event that happens in the daily life. This organized pattern of investigation is called a “SCIENTIFIC METHOD”.


The steps of the scientific method
  •  Step 1:- Identification of the problem which forms the basis of systematic observations.

  •    Step 2: - Posing questions and formulating of hypothesis based on them.

  •    Step 3: - Testing hypothesis by conducting experiments with controls where necessary

  •    Step 4: - Making predictions and test them by further experiments.

  •  Step 5: - Confirming predictions supported by evidences or observations.

  • Step 6: - Formulating a theory which may be modified in the light of new knowledge.

Experiment done by Flemming (1881 - 1955) 
  •  He did experiments with bacteria cultures. During his experiments, fungi which accidentally grew on his culture medium created many problems. Spores of fungi transmit through air and invade the bacterial culture medium. 
  • One day h observed that a light green colored fungi infected on the bacterial culture medium and the special observation he got there was the bacterial growth was inhibited around the fungi colony.
Step 1:- Observation - Bacteria has not grown at the region closer to the fungi.
              Problem - Why does the bacteria not grow around the fungi?

Step 2:- Hypothesis - Some substance which was secreted by fungi inhibit the growth of bacteria.

Step 3:- Test -

Alexander Flemming's experiment
Step 4:- Bacteria would not grow in a medium that contains the extraction of the fungi.

Step 5:- According to the result he got, the bacterial growth was inhibited by the substances that was secreted               by the fungi. By the above experiment he confirmed that the toxic substance called antibiotic secreted               by "PENICILLIUM" inhibits the growth of bacteria and that is the discovery of the antibiotic "PENICILLIN".


What is "The Theory" of  Scientific method?    
  • When a hypothesis is proved by repeated experiments, it is accepted as a theory. Although a hypothesis cannot be proven by experiments and if it can be accepted as a truth according to the observations & evidences for a longer period of time and hypothesis is then referred to as a "THEORY". 
  • Examples : Although the structure of an atom cannot be experimentally proven according to the evidences we can accept the 'Dalton's Atomic Model'.
  • When a hypothesis or a theory can be used to explain several concepts and circumstances in nature which are not inter-related and then those theories are known as "LAWS".
Scientific method cycle
Chemical And Cellular Basis Of Life
The elemental composition of living bodies

  • There are about 100 elements in the earth and only a few (about 20) of them are constituents of living matter.
  • The element which are in the biological systems are referred to as essential elements because,
  1. They are the major constituents of main structural components of the biological system.
  2. They are essential for the completion of life cycle and for the reproduction.
  • The essential elements are mainly of two types.
  1. Macro Elements - necessary in large amount and it it needed greater than 0.01% of the dry mass.
           Example:- For plants - O C H N S P K Ca Mg (arranged according to the weight)
                            For animals - O C H N S P K Ca Mg Fe Na Cl


     2.  Trace Elements - necessary in small quantities less than 0.01% of the dry mass
            Example:- B Mn Cu Zn Mo Al Si V
                              (Na, Fe, Cl are trace elements only for plants)
The most abundant element in the  biological systems then consider the number of atoms in molecules is 'H' and 'O'.

The most abundant inorganic compound in the living body is H2O (90-95%) And the inorganic compound is

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