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NCERT based - 11th Biology MCQ PDF
NCERT Based MCQ with Explanation:
1. What is the primary focus of modern biotechnology?
(a) Producing mechanical devices
(b) Using genetically modified organisms for products and processes
(c) Studying ancient biological systems
(d) Developing chemical fertilizers
Explanation: The chapter explains that modern biotechnology involves using genetically modified organisms to enhance processes like food production and health, distinguishing it from traditional methods.
2. Who is credited with observing the 'sticky ends' property of restriction enzymes?
(a) Stanley Cohen
(b) Herbert Boyer
(c) Rene Descartes
(d) European Federation of Biotechnology
Explanation: Herbert Boyer, in 1969, observed that restriction enzymes cut DNA strands leaving 'sticky ends,' facilitating precise DNA recombination.
3. What significant breakthrough did Boyer and Cohen achieve in 1972?
(a) Discovery of restriction enzymes
(b) Construction of the first recombinant DNA
(c) Invention of PCR
(d) Development of bioreactors
Explanation: The chapter highlights that Boyer and Cohen created the first recombinant DNA by combining an antibiotic resistance gene with a plasmid, laying the foundation for biotechnology.
4. What is the role of plasmids in biotechnology?
(a) They act as restriction enzymes
(b) They serve as vectors to transfer DNA into host cells
(c) They synthesize proteins directly
(d) They degrade DNA fragments
Explanation: Plasmids are small, circular DNA molecules that replicate independently and are used as vectors to carry foreign DNA into host cells.
5. Which of the following is NOT considered a form of traditional biotechnology?
(a) Making curd
(b) Producing wine
(c) Synthesizing a gene
(d) Baking bread
Explanation: Traditional biotechnology includes microbe-mediated processes like making curd, wine, and bread, while gene synthesis is a modern technique.
6. According to the European Federation of Biotechnology, what does biotechnology integrate?
(a) Physics and chemistry
(b) Natural sciences and organisms
(c) Engineering and mathematics
(d) Astronomy and biology
Explanation: The EFB defines biotechnology as the integration of natural sciences with organisms, cells, and molecular analogues for products and services.
7. What are the two core techniques of modern biotechnology?
(a) Genetic engineering and bioprocess engineering
(b) Physics and chemistry
(c) Astronomy and biology
(d) Mechanical and electrical engineering
Explanation: The chapter identifies genetic engineering (altering DNA) and bioprocess engineering (maintaining sterile conditions for production) as foundational to biotechnology.
NCERT Based - Geography 9th MCQ PDF8. What is the purpose of maintaining a sterile environment in bioprocess engineering?
(a) To increase DNA replication
(b) To grow only the desired organism in large quantities
(c) To prevent DNA cloning
(d) To degrade unwanted proteins
Explanation: Sterility ensures that only the intended microbe or cell grows, avoiding contamination during production.
9. Why does sexual reproduction provide an advantage over asexual reproduction in breeding?
(a) It preserves genetic information
(b) It allows variation and unique genetic combinations
(c) It prevents mutations
(d) It eliminates all undesirable genes
Explanation: Sexual reproduction introduces genetic variation, which can be beneficial, unlike asexual reproduction, which preserves existing genetics.
10. What limitation does traditional hybridisation have that genetic engineering overcomes?
(a) It cannot produce proteins
(b) It introduces undesirable genes along with desirable ones
(c) It requires sterile conditions
(d) It cannot use plasmids
Explanation: Genetic engineering allows precise insertion of only desired genes, unlike hybridisation, which often includes unwanted genes.
11. Why must alien DNA be linked to a chromosome’s origin of replication?
(a) To degrade the DNA
(b) To allow it to replicate in the host organism
(c) To prevent protein synthesis
(d) To remove sticky ends
Explanation: The origin of replication enables DNA to multiply within the host by initiating replication, a key step in cloning.
12. What enzyme was used by Cohen and Boyer to link DNA segments in their recombinant DNA experiment?
(a) Restriction endonuclease
(b) DNA ligase
(c) DNA polymerase
(d) Protease
Explanation: DNA ligase joins the ends of cut DNA molecules, forming recombinant DNA, as described in their 1972 experiment.
13. What bacterium was used as the host for the first recombinant DNA replication?
(a) Salmonella typhimurium
(b) Escherichia coli
(c) Agrobacterium tumifaciens
(d) Thermus aquaticus
Explanation: E. coli, a close relative of Salmonella, was used to replicate the recombinant DNA due to its well-understood genetics.
14. What are the three basic steps in genetically modifying an organism?
(a) Identifying DNA, introducing it to a host, maintaining it in progeny
(b) Cutting DNA, amplifying it, degrading it
(c) Synthesizing proteins, isolating enzymes, cloning vectors
(d) Growing cells, purifying RNA, staining DNA
Explanation: These steps outline the process of genetic modification: finding the gene, transferring it, and ensuring its inheritance.
15. Which tool is essential for cutting DNA at specific locations in recombinant DNA technology?
(a) DNA ligase
(b) Restriction enzymes
(c) Plasmids
(d) Polymerase
Explanation: Restriction enzymes act as 'molecular scissors,' cutting DNA at specific recognition sites for recombination.
16. What was the first restriction endonuclease characterized, and in what year?
(a) EcoRI, 1963
(b) Hind II, 1968
(c) BamH I, 1972
(d) Taq polymerase, 1985
Explanation: Hind II was isolated and characterized in 1968, recognizing a specific six-base-pair sequence.
17. How are restriction enzymes named?
(a) Based on their molecular weight
(b) First letter from genus, next two from species of the bacterium
(c) Random alphabetical order
(d) Based on the year of discovery
Explanation: For example, EcoRI is named from Escherichia coli RY13, with 'R' from the strain and 'I' indicating order of isolation.
18. What is the difference between exonucleases and endonucleases?
(a) Exonucleases cut within DNA; endonucleases cut at ends
(b) Exonucleases remove nucleotides from ends; endonucleases cut within DNA
(c) Exonucleases synthesize DNA; endonucleases degrade it
(d) Exonucleases are used in PCR; endonucleases are not
Explanation: The chapter distinguishes nucleases: exonucleases act at DNA ends, while endonucleases, like restriction enzymes, cut internally.
19. What feature of DNA do restriction endonucleases recognize?
(a) Sugar-phosphate backbone
(b) Palindromic nucleotide sequences
(c) Single-stranded regions
(d) Methylated bases
Explanation: Restriction enzymes bind to palindromic sequences (e.g., GAATTC), cutting DNA at specific points.
20. What are 'sticky ends' in DNA fragments?
(a) Blunt ends that cannot join
(b) Overhanging single-stranded portions that can bond with complementary ends
(c) Methylated DNA regions
(d) Fully double-stranded cuts
Explanation: Sticky ends, produced by restriction enzymes like EcoRI, facilitate DNA ligation by hydrogen bonding with matching sequences.
21. Which enzyme joins DNA fragments with sticky ends?
(a) Restriction endonuclease
(b) DNA ligase
(c) DNA polymerase
(d) Ribonuclease
22. Why must the vector and source DNA be cut with the same restriction enzyme?
(a) To ensure different sticky ends
(b) To produce compatible sticky ends for ligation
(c) To degrade the DNA completely
(d) To increase DNA size
23. What technique is used to separate DNA fragments after restriction enzyme digestion?
(a) PCR
(b) Gel electrophoresis
(c) Micro-injection
(d) Spooling
24. Why do DNA fragments move towards the anode in gel electrophoresis?
(a) They are positively charged
(b) They are negatively charged
(c) They are neutral
(d) They are hydrophobic
25. What is the most commonly used matrix in gel electrophoresis?
(a) Polyacrylamide
(b) Agarose
(c) Cellulose
(d) Silica
26. How are DNA fragments visualized after gel electrophoresis?
(a) By exposure to visible light
(b) By staining with ethidium bromide and UV light
(c) By adding sugar syrup
(d) By heating the gel
27. What is the process of extracting DNA fragments from an agarose gel called?
(a) Cloning
(b) Elution
(c) Amplification
(d) Transformation
28. What is a cloning vector?
(a) An enzyme that cuts DNA
(b) A DNA molecule used to carry foreign DNA into a host cell
(c) A protein that replicates DNA
(d) A bacterium that degrades DNA
29. Which of the following has a higher copy number per cell?
(a) Plasmids
(b) Bacteriophages
(c) Chromosomal DNA
(d) RNA molecules
30. What feature of a vector controls the replication of linked DNA?
(a) Selectable marker
(b) Origin of replication (ori)
(c) Cloning site
(d) Antibiotic resistance gene
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