NCERT Solutions for Class 12 Biology Chapter 9 Biotechnology Principles and Processes

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Students can download the PDF of this chapter from the link given below. After going through the PDF of Class 12 Biology Chapter 9 Biotechnology Principles and Processes question answer, students can answer all questions easily.

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Find Class 12 Biology Chapter 9 Biotechnology Principles and Processes Solutions (Exercise Questions)

Given below are the detailed answers to all the questions given in the textbook. Class 12 Biology Chapter 9 Biotechnology Principles and Processes question answer are prepared according to the latest NCERT guidelines, which provide knowledge about how biotechnology has changed our lives.

Q1. Can you list 10 recombinant proteins that are used in medical practice? Find out where they are used as therapeutics (use the internet).

Answer:

Recombinant proteins are proteins produced as a result of recombinant DNA technology. In this technology, there is the transfer of a specific gene from one organism to another by using molecular tools such as biological vectors, restriction enzymes, etc. Some of the proteins produced through RDT and are being used for therapeutic uses are as follows:

Q2. Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA, and the product it produces

Answer:

The following chart shows the action of the restriction enzyme EcoRI, the substrate DNA on which it acts, and the site where it cuts

Q3. From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

Answer:

DNA possesses all the genetic information of an organism. This genetic information can be transcribed into the form of proteins, multiprotein complexes, enzymes, etc. The actual length of DNA is in meters. The actual size of DNA is 2 meters long. Although they are present in condensed form. So they appear smaller when compared to enzymes. While enzymes, on the other hand, have variable sizes but are only a few nanometers in length. Hence, they will always be smaller when compared to DNA. Thus, we can conclude that DNA is bigger than enzymes.

Q4. What would be the molar concentration of human DNA in a human cell? Consult your teacher.

Answer:

The molar concentration of DNA in a human cell will be the total no. of chromosomes divided by 6.023 × 10²³

Hence, the molar concentration of DNA in each diploid cell in humans is 46/6.023 × 10²³ = 7.64 × 10^-23

Q5. Do eukaryotic cells have restriction endonucleases? Justify your answer.

Answer:

No, eukaryotic cells do not have bacterial-type restriction endonucleases. Restriction endonucleases have been isolated from bacteria where they act as a defence mechanism against invading viruses. Bacteria protect their own DNA from cleavage by methylation. Eukaryotes, instead, use different defence strategies such as nucleases, DNA methylation/repair systems, and RNA interference (which mainly targets viral RNA).

Q6. Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?

Answer:

The advantages of stirred tank bioreactors over shake flasks are as follows:

1. Stirred tank bioreactors are utilised for large-scale production of biotechnological products, unlike the shake flask method, which is used for small-scale production of products.

2. In stirred tank bioreactors, a small sample can be taken out for testing.

3. Stirred tank bioreactors have foam breakers to control the foam.

4. Stirred tank bioreactors have temperature and pH control systems.

Q7. Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following the base-pair rule

Answer:

Palindromic sequences in the DNA molecule refer to groups of bases forming the same sequence when read either backward or forward. The recognition sites of restriction endonucleases are palindromic sequences. Five examples of palindromic DNA sequences are given below

1. ACTAGT/TGATCA

2. AAGCTT/TTCGAA

3. GGATCC/CCTAGG

4. AGGCCT/TCCGGA

5. ACGCGT/TGCGCA

Q8. Can you recall meiosis and indicate at what stage a recombinant DNA is made?

Answer:

In meiosis, during the pachytene stage of Prophase I, crossing-over takes place and recombinant DNA is formed by combining portions of male and female DNA.

Q9. 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?

Answer:

In recombinant DNA technology, the selection of transformed and non-transformed cells can be done using reporter genes that encode reporter enzymes. During the RDT experiment, the foreign gene is joined with a reporter gene. The reporter gene should be such that it produces a visible expression. For example, the Lac Z gene, which codes for the enzyme beta-galactosidase, is used as a reporter gene. The activity of this gene is not found in transformed cells, as the product formed by its catalysis is not formed in transformed cells, and bacterial colonies appear white. In non-transformed cells, this gene shows its activity and the catalysed product is formed; as a result of this, bacterial colonies appear blue. Thus, a reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker.

Q10. Describe briefly the following:

(a) Origin of replication

Answer:

Origin of replication- This refers to the DNA sequence from which replication of DNA starts. By linking a DNA sequence with the origin of replication, it can be allowed to replicate in the host cells. The origin of replication also controls the copy number of linked DNA sequences.

(b) Bioreactor

Answer:

Bioreactors - These are vessels used for large-scale production of biotechnological products such as proteins, enzymes, etc., from raw materials. They can range from small laboratory fermenters (a few litres) to large industrial bioreactors (thousands of litres). In a bioreactor, optimum conditions such as temperature, pH, vitamins, oxygen, and salts are maintained. Stirred tank bioreactors are the most commonly used types, either as simple stirred tanks or sparged tanks.

(c) Downstream processing

Answer:

Downstream processing- The process of separation and purification of biotechnological products is called downstream processing. The processes in downstream processing vary depending on the quality of the product. Before the release of the product, it undergoes clinical trials and quality control testing.

Q11. Explain briefly :

(a) PCR

Answer:

Polymerase Chain Reaction (PCR)- The molecular technique to amplify a gene and obtain several copies is referred to as PCR. The process of PCR has certain requirements, i.e., a thermostable enzyme called Taq polymerase ( obtained from Thermus aquaticus ), primers ( short stretches of DNA ), dNTPs, a template strand, etc. The process of PCR takes place in three steps.

1. Denaturation- The double-stranded DNA helix is opened up by breaking its H-bonds at high temperatures.

2. Annealing- The primers are allowed to hybridise to complementary regions of DNA. This step takes place at a 50-65°C temperature.

3. Extension- The primers are extended with the help of the Taq polymerase enzyme, and the cycle is repeated several times to obtain the desired number of copies.

(b) Restriction enzymes and DNA

Answer:

Restriction enzymes and DNA- Restriction enzymes are those enzymes that cut DNA at particular places. The restriction enzyme first scans the DNA template and looks for its recognition site. Once it finds the recognition site, it binds at that region of DNA and cuts each of the two strands in its sugar-phosphate backbone. The sites at which restriction enzymes cut DNA are called recognition sites of DNA. These are palindromic sequences, i.e., they read similarly from the backward and forward direction.

(c) Chitinase

Answer:

Chitinase - The enzyme that catalyses the breakdown of chitin polysaccharide, which is usually found in the cell wall of fungi. Chitinase is mainly used during DNA isolation from fungi.

Q12. Discuss with your teacher and find out how to distinguish between

(a) Plasmid DNA and Chromosomal DNA

Answer:

The differences between plasmid DNA and chromosomal DNA are as follows:

(b) RNA and DNA

Answer:

The differences between RNA and DNA are as follows:

(c) Exonuclease and Endonuclease

Answer:

The differences between exonuclease and endonuclease are as follows:

NCERT Solutions for Class 12- Subject-wise

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Approach to Solve Biotechnology Principles and Processes Class 12 Question Answer

Given below are the steps that students can follow to solve the questions of the Biotechnology: Principles and Processes chapter effectively.

• Students must start by understanding the concepts, such as genetic engineering and recombinant DNA technology. These are well-explained in the Class 12 Biology Chapter 9 Biotechnology Principles and Processes question answer.

• Focus on the steps of recombinant DNA technology, such as isolation of DNA, cutting with enzymes, amplification using PCR, and insertion into host cells.

• Students should learn about the tools used in biotechnology, including restriction enzymes, ligases, and vectors, along with their functions and examples.

• Short notes of important definitions, steps, and diagrams can be prepared. Students can take help from the Class 12 Biology Chapter 9 Biotechnology Principles and Processes Solutions.

• Practice questions and diagram-based MCQs are given in the NCERT Solutions for Class 12. This makes students familiar with the exam pattern and improves their speed and accuracy.

Also, check the NCERT Books and the NCERT Syllabus here:

• NCERT Books Class 12 Biology

• NCERT Syllabus Class 12 Biology

• NCERT Books Class 12

• NCERT Syllabus Class 12

Important Question of NCERT Class 12 Biology Chapter 9

Given below is an important question from this chapter along with the answer. This helps students understand how the question appeared in the exam. To practice more such types of questions, students can refer to the NCERT Solutions for Class 12 Biology Chapter 9 Biotechnology Principles and Processes.

Question: Among the following statements, carefully identify the ones that contain incorrect information about the palindromic sequences.

A. Palindromic sequences are DNA sequences that read the same in both directions but have an antiparallel orientation.

B. Palindromic sequences are DNA sequences that read the same in both directions but have a parallel orientation.

C. Palindromic sequences are recognised by a specific restriction endonuclease, leading to specific cleavage.

D. Palindromic sequences are recognised by exonucleases, resulting in non-specific cleavage.

Choose the option(s) that contain incorrect statements:

Options:

1. A and C

2. A and D

3. B and C

4. B and D

Answer: The correct answer is option (4).

Explanation:

Statement B states that the Palindromic sequences are DNA sequences that read the same in both directions but have a parallel orientation. This statement is incorrect. Palindromic sequences have an antiparallel orientation, not a parallel one. Therefore, statement B is incorrect.

Statement D states that the palindromic sequences are recognized by exonucleases, resulting in non-specific cleavage. This statement is incorrect. Exonucleases degrade DNA from the ends, but they do not specifically recognize and cleave palindromic sequences. Therefore, statement D is incorrect.

Hence, the correct statements are B and D.

NCERT Exemplar Class 12 Solutions

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What Students Learn from Biotechnology Principles and Processes NCERT Solutions

This chapter gives students a clear idea about how scientists use modern techniques to work with DNA. It explains the step-by-step methods involved in developing recombinant DNA and other important things.

1. Students learn about restriction enzymes, cloning vectors, and the role of a competent host in genetic engineering.

2. Through the Biotechnology Principles and Processes NCERT Solutions, they understand the process of DNA isolation, cutting, and insertion into host organisms.

3. The chapter explains polymerase chain reaction (PCR), gel electrophoresis, and other important techniques.

4. With the help of the Biotechnology Principles and Processes Class 12 question answer, learners can easily revise concepts like bioreactors and downstream processing.

5. It highlights how recombinant DNA technology is applied to produce useful gene products such as insulin and other proteins.

What Extra Should Students Study Beyond the NCERT for NEET?

Given below is a table that includes the topics that students have to study beyond the NCERT to score well in the NEET exam. Students can refer to the NCERT Solutions for Class 12 Biology Chapter 9 Biotechnology Principles and Processes to understand the processes and diagrams.

NCERT Solutions for Class 12 Biology Chapter-wise

Below mentioned are the chapter-wise solutions for quick revision: