Biology: Branches, Concepts, Notes & NCERT Solutions

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Biology is the study of life and life processes. Biology is the basis for the scientific study of living organisms and their respective characteristics. Life science, medicine, conservation, genetics, microbiologyCell biology and various other fields are distributaries of the subject of Biology. Modern technology has led its way to Interdisciplinary research by integrating various disciplines such as Chemistry, physics and medicine to gear up the development in biology and its allied fields. In Class 12 syllabus, Biology subject is divided into Botany (study of plants) and Zoology (Study of animals).

Also Read: Comparison Articles in Biology

Branches of Biology

Branches of Biology


Aspects of Biology

The different aspects of biology and their subtopics are discussed below.

Taxonomic Hierarchy of Organisms

There are millions of living organisms in the world and without any classification, it is impossible to identify each of them separately. Thus, all the organisms are classified in a taxonomic hierarchy in the order of Kingdom → Phylum → Class → Class → Order → Family → GenusSpecies.

Below are some concepts that explains in detail about the Plant kingdom, morphology of plants and their functions.

Below are some concepts that explains in detail about the Animal kingdom, lifecycle of animals & insects, their functions and anatomy.


Ecology and Environment

All the living organisms in this world constantly interact with one another for the basic need of survival. The inter-relationship between these organisms determines the balance between environment and organisms. The food chain, biomass, energy pyramid, etc maintain the proportion and balance to lead a sustainable life.


Cell- Basic Unit of Life

Cell is the basic unit of life. Cells are broadly classified into Plant cells and animal cells. The only difference between the two is that animal cells don’t have a cell wall. Cells contains cell organelles which have different functions to promote the growth of the cell. Some of the cell organelles are the nucleus, mitochondria, vacuoles, cytoplasm, endoplasmic reticulum, cell wall, cell membrane, etc. The DNA or the genetic information is present inside the nucleus. 


Unicellular and Multicellular Organisms 

All organisms can be classified into unicellular or multicellular. Unicellular organisms are single celled microscopic organisms. Some of the examples of unicellular organisms are amoeba, paramoecium, euglena, etc. Apart from these, all other organisms are multicellular where a group of cell with common function makes up a tissue, tissues together form organ and organs together form organ system. 


Microbiology 

It is the study of microorganisms such as bacteria, virus, fungi, algae, etc. It is also necessary to study the characteristics and function of each of these organisms. Depending of the study of the subject, microbiology is classified into different fields such as bacteriology (study of bacteria), virology (study of viruses), mycology (study of fungus), etc.


Physiology, Health and Hygiene

It is very important to take good care of health and hygiene. The study of various organs of the human body and its functions forms a large portion of the subject. It also deals with the diseases that occurs in the body which may be either communicable or non-communicable diseases. The sources, preventive measures and treatment for these dieases also come under the purview of the subject.

Below are some articles that explains in detail about different physiological functions of human body and their respective organs.

Below are some articles that explains in detail about different hormones secreted in the human body and their respective functions.

Below are some articles that explains in detail about different types of vitamins and their deficiency diseases in the human body.


Genetics and Evolution

The passing on of characteristics from one generation to another is called heredity. Any minute changes in this gene transfer might cause a unique characteristic which forms the basis for evolution. Evolution has been the case since life appeared on earth. Evolution helps in adapting to the changing environment. 


CBSE CLASS XII Related Questions

  • 1.

    Given below are the diagrammatic representations of the replicating fork of DNA in E. coli. Study the diagrams and answer the questions that follow.

    (a) Which one of the three diagrams (i), (ii) or (iii) is the correct representation of the replicating fork of DNA replication? Explain your answer.
    (b) Name the enzyme used in E. coli to join the newly synthesised fragments of DNA.


      • 2.

        Answer the following questions:
        1. State what do you understand by “MALT”? Where is it located inside our body?
        2. Explain cytokine barriers.
        3. Name the diagnostic test for AIDS. On what principle does it work?
        4. Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this.


          • 3.


            Study the diagram above and answer the following questions:
            (a) How many alleles are involved in blood grouping?

            (b) A person having 'AB' blood group has both dominant alleles. What is this inheritance type called?

            (c) A man with 'A' blood group marries a woman with 'B' blood group. Can they have a child with 'O' blood group? Explain with the help of a cross.


              • 4.
                Given below are few statements with reference to the uterus in the female reproductive system:

                  • The myometrium exhibits strong contractions during the delivery of the baby.
                  • The uterus opens into the cervix through a narrow opening called vagina.
                  • The cavity of the cervix and the vagina forms the birth canal.
                  • The outermost layer of uterus is a thin membranous perimetrium.

                • 5.
                  Describe the structure and working of a sparged stirred-tank bioreactor.


                    • 6.

                      Study the graphs given below for Case 1 and Case 2 showing different levels of certain hormones and answer the question that follows:

                      (a) Which hormone is responsible for the peak observed in Case 1 and Case 2? Write one function of that hormone.
                      (b) Write changes that take place in the ovary and uterus during follicular phase. 
                      Student to attempt either sub-part (c) or (d): 
                      (c) Name the hormone Q of Case 2. Write one function of hormone Q. 
                       OR 
                      (d) Which structure in the ovary will remain functional in Case 2? How is it formed?

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