Unit 1

An introduction to Biology    

Biology is the science of life, which studies about living organisms and how they interact with one another and with their environment. There is a dynamic relationship between the world of life and the inanimate world.    

                                  Plants                                                   Animals

                                                           Non- Living things

                                                         E.g:- H20( water)

                                                                  Sunlight

                                                                  Minerals

                                                                  Temperature

                                                                  Wind

There had been life on earth for over 3.5 Billion years. There are around 30 million species of animals and plants in the world. 

The importance of studying Biology 

1. Understanding biological diversity.
2. Understanding the human body and it's functions.

• The organization of the human body, shows how systems within the body are interconnected and the way structure is related to function.

      3. Management of natural resources and environment.

• The natural resources are limited in nature and with the current increase in growth of human population, there is a threat of depletion of natural resources.

 e.g:- Global warming
         Acid rain
         Depletion of ozone layer
   
      4. Sustainable food production.

• With the current rate of population growth, 3 people are added to the world's population each second.
• The current human population of 6 Billion is expected to double in less than 40 years. Therefore, for the survival of mankind, sustainable food production is necessary.

 e.g:- High yielding products are cultivated.
         Disease free plants and animals should be cultivated.
         We should develop post harvest methods.

Understanding causes and effects of diseases.

With the rapid expansion of population, new diseases arise from time to time.
E.g:- Malaria
         AIDS
         Dengue
         Chickengunya
         Cancer etc.....
Therefore scientists are working on prevention and remedial measures and cure for diseases.

The organizational patterns of the living world.

Living organisms show a wide range of variations in size, shape, form and distribution.
E.g:- Size: Bacteria cell (Microscopic)- 0.25 μm- 2.00 μm                 μm= micrometre

                 Giant red wood tree= 100m tall.                                           1,000,000 μm = 1m   

                

         Form: Organisms are diverse in shape.

                    E.g:- Unicellular (Ameoba)  

                             Multicellular organisms. ( Animals and plants)

         Distribution: Terrestrial organisms, Aquatic (Fresh, Marine)

                               Arboreal (Monkeys)

                               Aerial (Birds)

Exercise   

Put  ✓ or X symbol in front of the following sentences. If you think a specific sentence is correct, put the symbol  ✓ cthe check box in front of it. If you think it's wrong, put X sign in front of it. 

1. The oldest fossil is 3.5 Billion years old.      ☐
2. The reason for global warming is due to increased carbon dioxide concentration in Atmosphere. ☐
3. Causative agent for AIDS is a bacteria. ☐
4. The current human population is 3 Billion. ☐
5. Three people are added to the worlds population each second. ☐   

Answers. 
Q 1-  ✓
Q 2- ✓
Q 3-  X=> Virus
Q 4- X  => 7 Billion
Q 5-  ✓

Effects of Global Warming.

• Rising of sea level due to melting of ice glaziers.
• High temperature.

Characteristics of living organisms. 

1. Order and organization.

• From Molecular level to biosphere level there is and order and organization in organisms to perform on their biological activities efficiently.
• In this hierarchical order, at every level, structure and function are different.

  

   
Metabolism

• The sum of all chemical activities taking place in an organism is it's metabolism. It includes 2 parts. Catabolic and anabolic reactions.

Catabolism

• Breaking down complex molecules. 

          E.g:- C6H12O6 + O2 H2O + CO2

Anabolic reactions

• Building up complex molecules.

         E.g:-

Growth and development

• All organisms begin their life as a single cell. During growth, an irreversible increase in dry mass occurs, which is characterized only by the Living. Growth and development are two consequent processes that happen in the life of organisms.

Irritability and coordination

• Irritability is the ability to respond to a stimuli from both internal and external environment.  Movement of organisms occur as the result of irritability and coordination.

           E.g:- In animals this happens as a result of coordinated efforts of nervous, muscular and             skeletal systems.

Adaptation 

Adaptation is the specularity of structure.Physiology of behaviour that promotes the livelihood of organisms survival and reproduction in a particlure environment. 

• Eg:- sunken stomata in xerophytes

      Collect out put of camel prevents the foot sinking in sand.

Reproduction

• Ability to reproduce a new offspring for continuous existence of species.

  Heredity and evolution

•          Organisms have genes that pass from one generation the next and control specific physiological and morphological characters.

• ·        Ability of organisms to change over time as a result of genetic modifications of species.

 Many non- living entities may have one or more of these characteristics but not all of them.           Eg:- crystals grow,waves move but only living organisms disaplay all these characteristics simultaneously or at some point during there life cycle.

  The cell is considerd as the basic structural and functional unit in the hierarchial levels of an organism.