Title 28.MOLECULER BASIS OF INHERITANCE.pdf ✅

CHAPTER 5 MOLECULER BASIS OF INHERITANCE Exercise 1 : NCERT Based Topic-wise MCQs 5.1 DNA 1. The two strands of DNA are held together by NCERT Page-97 / N-81 (a) peptide bonds (b) phosphodiester bonds (c) hydrogen bonds (d) S − S bonds 2. Chargaff's rules are applicable to NCERT Page-97 / N-81 (a) single stranded RNA. (b) single stranded DNA and RNA. (c) single stranded DNA. (d) double stranded DNA. 3. Histones are rich in NCERT Page-99 / N-83 (a) alanine and glycine (b) lysine and arginine (c) histidine and serine (d) cysteine and tyrosine 4. Nucleotides are linked by NCERT Page-96 / N-81 (a) hydrogen bonds (b) phosphodiester bonds. (c) peptic bonds. (d) ionic bonds. 5. Which one of the following pair is a purine pair? NCERT Page-96 / N-81 (a) Uracil, Guanine (b) Cytosine, Thymine (c) Adenine, Guanine (d) Adenine, Thymine 6. The two strands of a double helix model of DNA are held together by hydrogen bonds between (a) sugar and phosphate groups. NCERT Page-98 / N-82 (b) sugar and nitrogenous bases. (c) phosphate groups and nitrogenous bases. (d) nitrogenous bases. 7. Information flow or central dogma of modern biology is NCERT Page-98 / N-82 (a) RNA → Proteins → DNA (b) DNA → RNA → RNA (c) RNA → DNA → Proteins (d) DNA → RNA → Proteins
8. If a double stranded DNA has 20% of cytosine, what will be the percentage of adenine in it? (a) 20% (b) 40% (c) 30% (d) 60% 9. Refer to the given figure. NCERT Page-98 / N-82 Select the option which correctly identifies K, L, M and N. K L M N (a) 5 ′ end Phosphodiester bond Thymine Ribose sugar (b) 3 ′ end Glycosidic bond Guanine Deoxyribose sugar (c) 5 ′ end Hydrogen bond Adenine Ribose sugar (d) 5 ′ end Hydrogen bond Adenine Deoxyribose sugar 10. In sea urchin DNA, which is double stranded, 17% of the bases were shown to be cytosine. The percentages of the other three bases expected to be present in this DNA are (a) G- 17%, A − 16.5%, T − 32.5% NCERT Page-97 / N-81 (b) G − 17%, A − 33%, T − 33% (c) G-8.5%, A-50%, T-24.5% (d) G-34%, A-24.5%, T-24.5% 11. The diagram given below shows an important concept (proposed by C) in the genetic implication of DNA. The process occuring in that concept are marked as A and B. Identify A, B and C. NCERT Page-98 / N-82 (a) A-Translation, B - Transcription, C-Erwin Chargaff (b) A-Transcription, B - Translation, C-Francis Crick (c) A-Translation, B - Extension, C-Rosalind Franklin (d) A-Transcription, B - Replication, C-James Watson 12. Percentage of (G + C) is (a) G+C (A+G+T+C) × 100 (b) 100 A+T × G + C (c) G+C A+T+G+C (d) (G+C)×(A+T) 100 13. The structure in chromatin seen as 'breads-on string when viewed under electron microscope are called (a) nucleotides NCERT Page-99 / N-83
(b) nucleosides (c) histone octamer (d) nucleosomes 14. Refer the given figure of nucleosome and select the option that correctly identifies the parts A, B and C. NCERT Page-99 / N-83 A B C (a) DNA Histone octamer H1 histone (b) Histone octamer H1 histone DNA (c) Histone octamer DNA H1 histone (d) DNA H1 histone Octamer 15. Histone proteins are H1 histone NCERT Page-99 / N-83 (a) basic, negatively charged (b) basic, positively charged (c) acidic, positively charged (d) acidic, negatively charged 5.2 THE SEARCH FOR GENETIC MATERIAL 16. In Streptococcus pneumoniae NCERT Page-100 / N-84 (a) virulent form is smooth. (b) virulent form is rough. (c) nonvirulent form is capsulated. (d) all forms are rough. 17. The scientists involved in discovery of DNA as chemical basis of heredity were NCERT Page-101/ N-85 (a) Hershey and Chase (b) Griffith and Avery (c) Avery, Mac Leod and McCarty (d) Watson and Crick 18. Which of the following is correct for Watson and Crick's model of DNA. It is duplex with (a) 10 base pairs and 3.4Å distance for every turn. NCERT Page-97 / N-82 (b) 10 base pairs and 3.4Å distance for each turn of spiral. (c) 20 base pairs and 34Å for each turn. (d) None of the above 19. In Meselson and Stahl's experiments, heavy DNA was distinguished from normal DNA by centrifugation in (a) CsOH gradient NCERT Page-105 / N-89 (b) 14NH4Cl (c) 15NH4Cl (d) CsCl gradient 20. A bacterium grown over medium having radioactive 35S incorporates radioactivity in (a) carbohydrates NCERT Page-102 / N-86 (c) DNA