NIOS Class 12 Biology Chapter 24 Genetics and Society

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NIOS Class 12 Biology Chapter 24 Genetics and Society

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Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Biology Chapter 24 Genetics and Society Solutions, NIOS Senior Secondary Course Biology Solutions for All Chapter, You can practice these here.

Genetics and Society

Chapter: 24

MODULE – III: REPRODUCTION AND HEREDITY

NIOS TEXTBOOK QUESTIONS ANSWERS

INTEXT QUESTIONS 24.1

1. Name any two recent techniques in genetics.

Ans: (i) Genetic engineering.

(ii) DNA fingerprinting.

2. Define gene cloning.

Ans: It refers “to the technique of producing many identical copies of a particular gene”.

3. What is a gene bank?

Ans: The gene bank refers “to the collection of all genes of humans or genes of any other organism in different clones of bacteria”.

INTEXT QUESTIONS 24.2

1. What is the popular term for recombinant DNA technology?

Ans: Genetic Engineering.

2. What is meant by DNA splicing?

Ans: It refers to the joining of two pieces of DNA that belong to different species”.

3. What is a plasmid and why is it called a vector for genetic engineering?

Ans: Plasmid is defined as “a separate round piece of DNA found in bacteria that is used to carry desired gene from a particular organism into the bacteria”.

INTEXT QUESTIONS 24.3

1. Use the example of Bt crops to state importance of transgenic crops.

Ans: Transgenic crop like Bt crops reduce the need for use of insecticides which are toxic to humans and other animals.

2. What is a cry protein?

Ans: Cry protein produced by Bt crop. T causes toxicity poisoning when it enters pest stomach killing pest.

3. Exploiting a biological resource of another country without being authorised is called _________.

Ans: Biopiracy.

4. When and why was the biopatent act adopted in India?

Ans: In 1970, to provide patents.

5. What is the duration of a patent of pharmaceutical products in India? 

Ans: 20 years.

INTEXT QUESTIONS 24.4

1. Define genome.

Ans: Genome is “a collective term for full set of genes of an organism”.

2. What is Genomics?

Ans: It is the science of analysis of genes in the DNA of an organism relating each gene to its function.

3. What is the use of genomics?

Ans: Helps to identify the defective genes so that correction may be possible by gene therapy. 

4. Why should a genetic counsellor have good knowledge of genetics?

Ans: Since the counsellor has to advise regarding possibility of genetic disorder in next generations.

5. Expand the abbreviation PCR.

Ans: PCR = Polymerase chain Reaction.

6. Why is the technique DNA fingerprinting named so?

Ans: Since it is used to distinguish the fingerprints of persons in investigation of a crime.

TERMINAL EXERCISES

1. Name the three eras in the history of genetics. 

Ans: Three eras in the History of Genetics: They are early ideas, modern genetics and molecular genetics.

(i) From the prehistoric times, the man have had a curiosity to know how traits are inherited.

The domestication of animals as well as cultivation of crops such as wheat, maize and rice as well as date palm may be traced to earlier that 5000 BC.

(ii) Modern Genetics. It started after Mendel’s laws of inheritance were accepted. Soon after it becomes clear that “genes are carriers of hereditary traits”. Genes are found on chromosomes. The genes mutate.

(iii) Molecular Genetics. Last 50 to 60 years have been an era of Molecular Genetics. Now it was confirmed that “DNA is genetic material”. Mechanism of DNA replication as well as protein synthesis in the cell were invented.

2. Define gene cloning. What is the usefulness of a gene bank?

Ans: Gene Cloning: It is “a technique to get clones or identical copies of specific DNA molecule or genes”.

Gene cloning: It includes isolation and fragmentation of the source DNA and incorporation of the fragments obtained into a cloning vector (segment of DNA used for replication of foreign DNA fragments), with the use of restriction endonucleases to cut and ligase to region DNA molecules.

Usefulness of Gene Bank: It is possible to identify a clone containing the gene of interest. When a certain gene is required in large amounts, it is isolated and is grown on a synthetic medium to multiply in order to obtain the required gene. Thus gene bank preserves the genes.

3. Give the various steps of recombinant DNA technology.

Ans: Various steps of the Recombinant DNA Technology (r-DNA technology): It includes the following steps:

(a) Cells with desired DNA are obtained by cell culture/tissue culture.

(b) Selection of particular restriction en-donuclease from a specific bacterium.

(c) Cleaving of Desired DNA fragment or gene from the cells by restriction enzyme.

(d) Same restriction enzyme cuts plasmid for matching DNA sequences.

(e) Desired gene is united to the cut segment of plasmids of molecular glue or ligase enzyme and formation of Recom-binant DNA.

(f) The plasmid is inserted into its bacterium (e.g., E. coli). It is done by electroporation. During this process temporary holes are made in the plasma membrane through which foreign DNA is inserted into the cell.

(g) The bacterial host divides many times to make copies of recombinant DNA.

Fig. 24.3. Major steps in genetic engineering.

4. What are the benefits of genetic engineering?

Ans: Benefits of Genetic Engineering: The genetic engineering (r-DNA technology) can be used for different purposes as:

(i) To manufacture enzymes used to make cheese.

(ii) To manufacture compounds such as hormones, vaccines, vitamins, antibodies etc. Production of these substances by inserting genes responsible for them in bacteria and obtaining clones of these bacteria used to produce desired substances at all.

(iii) To use of rDNA for gene therapy to cure heredity disorders.

(iv) To breakdown pollutants through recombinant bacteria. It is called bioremediation.

(v) To raise useful plants resistant to herbicides or insect pests by inserting genes in plants through this technology. 

(vi) To clone specific genes by help of rDNA technology, so as to build up a gene bank or a gene library.

(vii) Sequencing of genes.

(viii) Exploration of genes.

5. What are transgenics? Give examples of a transgenic microbe, plant and animal.

Ans: Transgenics: The transgenics are also called genetically modified organisms (GM organisms). They contain in their genetic make up foreign genes, (genes from another species or another kind of organism). Transgenics are developed through r-DNA technology (gene splicing).

Transgenic bacteria are used to decompose pollutants and to extract heavy metals (Cu and Ag). Transgenic plants are used as herbicide and pest resistant plant. Transgenic cow gives more milk rich in lactalbumin.

6. Define genomics.

Ans: Genomics: It explains the scientific discipline of mapping, sequencing and analysing the genomes. This term was coined by Thomas Roderick (1986).

The genomics “a collective term for a full set of genes in an organism”. The genes are pairer The genome means “all the genes present in haploid (N) set of chromosomes.” Genomics “analysis of the genome data (finding o functional nucleotide sequences or genes in DN of an organism.”

Fig. 24.4. Chromosomes of (A) Male, (B) Female humans.

7. Draw and explain a pedigree chart. 

Ans: Pedigree Chart: It is “a diagrammatic repre-sentation of family relationship showing a specific trait or character”. Human genetics is studied by pedigree analysis. Genetic principles equally apply to plants as well as man. Man is not suitable for genetic study because:

(i) It cannot be kept in laboratory.

(ii) Life span is long and a scientist can study on 5-6 generations of a human being.

(iii) Selected mating not possible due to society laws and customs.

(iv) Number of offsprings is small.

In pedigree analysis traits are studied in man for past several generations.

(ii) Female is shown by a circle.

(iii) Carrier female by.

(iv) Solid symbols for affected individual.

(v) Mated pair connected by horizontal line.

(vi) Vertical line connect offspring from the parental couple.

(vii) Roman Numerals show generations I, II, III etc.

(viii) Position of offspring is indicated by 1, 2, 3, 4, __________ Arabic Numerals.

8. What is genetic counselling and why is it important?

Ans: Genetic Counselling: The advice given by a geneticist to improve health of a person or about a hereditary disease is called genetic counselling. Hereditary diseases are transmitted from one generation to the other. The role of genetic counsellor is to inform the concerned individuals of the nature of the mutant condition that concerns them.

9. What is DNA fingerprinting? Justify that it is the foolproof technique for sorting out paternity issues.

Ans: DNA fingerprinting refers “to a technique to identify DNA of a specific person.” This is Used to scientifically investigate a crime and identify real criminal also. Paternity issues are solved by it by matching fingerprints of persons.

10. List the steps of Polymerase chain reaction.

Ans. Steps of PCR, they include:

(a) Devatuation.

(b) Annealing of Primer. and 

(c) The extension of the Primers.

11. What are Bt crops? What are the benefits and fearns related to their use?

Ans: Bt crops: They are genetically modified or GM crops. They refer to transgenic crops. Foreign give is transferred into crop by Bt or Bacillus thuringiensis bacteria. They are Bt resistant, GM crops. They may act as superweeds. They may harm the environment.

12. Write notes on:

(i) Biopatent.

Ans: Bio patent: It refers to a document that permits a holder to use or sell its invention.

(ii) Biopiracy.

Ans: Biopiracy: Exploiting a biological resource of another country without that’s permission is biopiracy.

(iii) Necessity for a biosafety protocol.

Ans: Necessity for Biosafety: Salmonfish is modified genetically. Safety protocol is obtained. GM organism is tested before releasing it in environment.