Biotechnology: Principles and Processes Chapter 11 Class 12 Biology NCERT Textbook PDF

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Biotechnology Principles and Processes

Chapter 11: Biotechnology: Principles and Processes

Biotechnology deals with techniques of using live organisms or enzymes from organisms to produce products and processes useful to humans.

In this sense, making curd, bread, or wine, which are all microbe-mediated processes could also be thought of as a form of biotechnology.

However, it is used in a restricted sense today, to refer to those processes which use
genetically modified organisms to achieve the same on a larger scale. Further, many other processes/techniques are also included in biotechnology.

For example, in vitro fertilization leads to a ‘test-tube’ baby, synthesizing a gene and using it, developing a DNA vaccine, or correcting a defective gene, are all part of biotechnology.

The European Federation of Biotechnology (EFB) has given a definition of biotechnology that encompasses both traditional views and modern molecular biotechnology.

The definition given by EFB is as follows: The integration of natural science and organisms, cells, parts thereof, and molecular analogs for products and services.

11.1 Principles Of Biotechnology

Among many, the two core techniques that enabled the birth of modern biotechnology are :

(i) Genetic engineering: Techniques to alter the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism.

(ii) Bioprocess engineering: Maintenance of sterile (microbial contamination-free) the ambiance in chemical engineering processes to enable the growth of only the desired microbe/eukaryotic cell in
large quantities for the manufacture of biotechnological products like antibiotics, vaccines, enzymes, etc.

Let us now understand the conceptual development of the principles of genetic engineering.
You probably appreciate the advantages of sexual reproduction over asexual reproduction.

The former provides opportunities for variations and formulation of unique combinations of genetic setup, some of which may be beneficial to the organism as well as the population.

Asexual reproduction preserves genetic information, while sexual reproduction permits variation.

Traditional hybridization procedures used in plant and animal breeding very often lead to the inclusion and multiplication of undesirable genes along with the desired genes.

The techniques of genetic engineering include the creation of recombinant DNA, the use of
gene cloning and gene transfer, overcome this limitation and allows us to isolate and introduce only one or a set of desirable genes without introducing undesirable genes into the target organism.

Do you know the likely fate of a piece of DNA, which is somehow transferred into an alien organism?

Most likely, this piece of DNA would not be able to multiply itself in the progeny cells of the organism.

But, when it gets integrated into the genome of the recipient, it may multiply and be inherited along with the host DNA.

This is because the alien piece of DNA has become part of a chromosome, which has the ability to replicate.

In a chromosome, there is a specific DNA sequence called the origin of replication, which is responsible for initiating replication.

Therefore, for the multiplication of any alien piece of DNA in an organism, it needs to be a part of a chromosome(s) that has a specific sequence known as the ‘origin of replication.

Thus, alien DNA is linked with the origin of replication, so, this alien piece of DNA can replicate and multiply itself in the host organism. This can also be called cloning or making multiple identical copies of any template DNA.

Language English
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NCERT Solutions Class 12 Biology Chapter 11 Biotechnology: Principles and Processes

3. From what you have learned, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?


Compared to DNA molecules, enzymes are smaller in size. We can say this as DNA comprises of genetic material, essential for the normal development and functioning of living entities.

A DNA molecule consists of instructions required for the synthesis of DNA molecules and proteins. Whereas enzymes are the proteins that are synthesized from genes – a small fragment of DNA. These are crucial in the production of the polypeptide chain

5. Do eukaryotic cells have restriction endonucleases? Justify your answer.


No, eukaryotic cells do not have restriction endonucleases as the DNA of eukaryotes is highly methylated by methylase – a modification enzyme.

This methylation safeguards the DNA from the action of restriction enzymes. In prokaryotic cells, these enzymes are present where they aid in preventing the invasion of DNA by viruses.

6. Besides better aeration and mixing properties, what other advantages do stir tank bioreactors have over shake flasks?


Stirred tank bioreactors are developed for the large-scale production of biotechnology products whereas the shake flask method is applied for small-scale production of biotechnological products carried out in a laboratory.

The stirred tank bioreactor has few advantages over shake flasks. They are:

(i) For the testing and sampling process, small amounts of culture can be drawn out from the reactor

(ii) Presence of a control system to regulate the pH and temperature

(iii) To regulate the foam, the stirred tank bioreactors have a foam breaker

8. Can you recall meiosis and indicate at what stage a recombinant DNA is made?


A process involving a reduction in the quantity of genetic material is termed Meiosis, which is a type of cell division. It occurs in two phases, namely – meiosis I and meiosis II.

In the pachytene event of prophase I, chromosomes cross over wherein the exchange of segments between non-sister chromatids of homologous chromosomes occurs. This leads to the formation of recombinant DNA in the process of meiosis.

9. Can you think and answer how a reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker?


To monitor the transformation of host cells by foreign DNA, a reporter gene can be used. They serve as a selectable marker to find out if the host cell has used up the foreign DNA else the foreign gene is expressed in the cell.

The reporter gene and the foreign gene are placed by scientists in the same DNA construct.

This collective DNA construct is introduced into the cell where the reporter gene is used as a selectable marker to discover the successful uptake of foreign genes or the genes of interest. In a jellyfish, lac Z gene is an example of a reporter gene that encodes for a green fluorescent protein.

Biotechnology: Principles and Processes NCERT Textbook With Solutions PDF Free Download

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