NBSE Question Papers Biology Term-1 (Set-2) for Class 12

Class 12  TERM-I SET-2 Series NBSE/XII/2021 Code No. 044/12/2 Roll No.  Candidates must write the Code No. on the title page of the OMR sheet. l Please check that this question paper contains 12 printed pages. l Code number given on the right hand side of the question paper should be written on the title page of the OMR sheet. l Please check that this question paper contains 60 questions. l 15 minutes time has been allotted to read this question paper. BIOLOGY Maximum Marks : 35 Time Allowed : 90 Minutes General Instructions: 1. The Question Paper contains three sections. 2. Section A has 24 questions. Attempt any 20 questions. 3. Section B has 24 questions. Attempt any 20 questions. 4. Section C has 12 questions. Attempt any 10 questions. 5. All questions carry equal marks. 6. There is no negative marking. NBSE 2021 1 [P[P.T.T.O.O..

SECTION – A Section – A consists of 24 questions. Attempt any 20 questions from this section. The first attempted 20 questions would be evaluated. 1. Identify 'A' and 'B' in the given diagram of a transverse section of a young anther. A B (a) A — Tapetum B — Sporogenous tissue (b) A — Sporogenous tissue B — Tapetum (c) A — Connective B — Epidermis (d) A — Endothecium B — Tapetum 2. Identify ‘A’ and ‘B’ in the following diagram of a mature pollen grain A B (a) A — Generative cell B — Vegetative cell (b) A — Vegetative cell B — Generative cell (c) A — Nacuole B — Nucellus (d) A — Nucleus B — Vacuole 3. The coconut water from tender coconut represents (a) endocarp (b) free nuclear endosperm (c) free nuclear embryo (d) mesocarp 4. Intine is composed of (b) lipoproteins (a) pectocellulose (c) sporopollenin (d) glycoproteins NBSE 2021 2

5. Identify (P) and (Q) in the following diagram of a typical dicot embryo. P Q (a) P — Cotyledons Q — Root cap (b) P — Hypocotyl Q — Root cap (c) P — Cotyledon Q — Plumule (d) P — Plumule Q — Radicle 6. Which of the following hormones is not secreted by human placenta? (a) hCG (b) hPL (c) Estrogen (d) LH 7. Study the given diagram Transforms into C D AB A is the embryonic stage that gets transformed into B, which in turn gets implanted in the endometrium in human females. Identify A,B and its parts C and D (a) A — morula, B-blastomere, C- blastula D-inner cell mass (b) A — blastula, B-gastrula, C- trophoblast, D-inner cell mass (c) A — morula B- blastocyst C- stem cells D-trophoblast (d) A — blastocyst B-trophoblast C-stem cells D-morula 8. Zona pellucida disintegrates just (b) after fertilisation (a) before fertilisation (c) after the completion of cleavage (d) before implantation 9. Hormones secreted by placenta to maintain pregnancy are (a) hCG, hPL , progestogen, prolactin (b) hCG , progestogen, estrogen, glucocorticoids (c) hCG , hPL , progestogen, estrogen (d) hCG , hPL , estrogen, relaxin, oxytocin NBSE 2021 3 [P[P.T.T.O.O..

10. Match the terms in column I with the items in column II. Column I Column II 1. Autogamy ( A) T ransfer of pollen grains from anther to stigma of the same flower 2. Geitonogamy (B) Transfer of pollen grains from anther to stigma of flower of another plant of simi- lar type. 3. Xenogamy (C) transfer of pollen grains from the anther to the stigma of another flower of the same plant (a) 1–A, 2–C,3–B (b) 1–A, 2–B, 3–C (c) 1–C, 2–B, 3–A (d) 1–B, 2–A, 3–C 11. Apple and strawberry are (a) false fruits (b) true fruits (c) parthenocarpic fruits (d) none of these 12. How many sperms and ova will be produced from 50 primary spermatocytes and 50 oocytes respectively (a) 200 sperms,50 ova (b) 100 sperms, 200 ova (c) 100 sperms, 50 ova (d) 50 sperms, 100 ova 13. In the F2 generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are (a) phenotypes - 4; genotypes – 16 (b) phenotypes - 9; genotypes – 4 (c) phenotypes - 4; genotypes – 8 (d) phenotypes - 4; genotypes – 9 14. Three children in a family have blood types O, AB and B respectively. What are the genotypes of their parents? (a) IA IA and IB IO (b) IA IO and IB IO (c) IB IB and IA IA (d) None of these 15. Name the inborn error of metabolism that is inherited as an Autosomal recessive trait, The disease is characterized by the absence of phenylalanine hydroxylase in affected individual (a) Thalassemia (b) Phenyl ketonuria (c) Sickle cell anaemia (d) Colour blindness 16. 2A + XO Drosophila is (b) intersex (a) sterile male (c) fertile female (d) infertile female 17. Conditions of a karyotype 2n+1, 2n–1 and 2n+2, 2n–2 are called (a) Aneuploidy (b) Polyploidy (c) Allopolyploidy (d) Monosomy NBSE 2021 4

18. In the DNA molecule (a) the proportion of adenine in relation to thymine varies with the organism (b) there are two strands which run antiparallel—one in 5' → 3' direction and other in 3' → 5' (c) the total amount of purine nucleotides and pyrimidine nucleotides is not always equal (d) there are two strands which run parallel in the 5' → 3' direction 19. Replication of DNA in eukaryotes commences from (a) one end of the chromatid extending to the other end (b) both ends of the chromatid simultaneously (c) the centromere to either of the ends of chromatids (d) several sites along the DNA of the chromatid simultaneously 20. Which is the correct sequence of code transfer involved in the formation of polypeptide? (a) DNA, tRNA, RNA and mRNA (b) RNA,DNA, mRNA, tRNA (c) mRNA, tRNA, DNA, amino acids (d) DNA, mRNA, tRNA, amino acids 21. In E.coli, the lac operon gets switched on when (a) lactose is present and it binds to the repressor (b) repressor binds to operator (c) RNA polymerase binds to the operator (d) lactose is present and it binds to RNA polymerase 22. Find out the correct answers out of the following discoveries. 1. Griffith - transformation 2. Gamow - triplet code 3. Meischer - nucleic acid (a) 1, 2 and 3 are correct (b) 1 and 2 are correct, 3 is incorrect (c) 1 is correct, 2 and 3 are incorrect (d) 1 and 3 are correct, 2 is incorrect 23. The base pairs of DNA double helix is given below. Select the suitable mRNA strand that derived from transcription is 3'-ATTTCC-5' 5'-TAAAGG-3' (a) UAAAGG (b) CUUUCC (c) GAAAGG (d) CCUUUC 24. A bacterium E.coli with completely radioactive DNA was allowed to replicate in a non- radioactive medium for two generations. What percentage of the bacteria should contain radioactive DNA? (a) 100% (b) 25% (c) 50% (d) 12.5% NBSE 2021 5 [P[P.T.T.O.O..

SECTION – B Section - B consists of 24 questions (Sl. No. 25 to 48). Attempt any 20 questions from this section. The first attempted 20 questions would be evaluated. 25. Assertion: Lactational amenorrhea is a natural method of contraception. Reason: Ovulation does not take place during the period of intense lactation following child birth. (a) Assertion and the Reason are true and the Reason is a correct explanation of the Assertion. (b) Assertion and Reason are true but the Reason is not a correct explanation of the Assertion. (c) Assertion is true but the Reason is false. (d) Assertion is false but the Reason is true. 26. Assertion: Oral contraceptive pills are effective method of contraception with few side effects. Reason: Oral pills like Saheli inhibit ovulation and implantation. (a) Assertion and the Reason are true and the Reason is a correct explanation of the Assertion. (b) Assertion and Reason are true but the Reason is not a correct explanation of the Assertion. (c) Assertion is true but the Reason is false. (d) Assertion is false but the Reason is true. 27. With regard to mature mRNA in eukaryotes which of the following is true? (a) Exons and introns do not appear in the mature RNA (b) Exons appear but introns do not appear in the mature mRNA (c) Introns appear but exons do not appear in the mature mRNA (d) Both exons and introns appear in the mature mRNA 28. Assertion: DNA is considered to be a better genetic material than RNA for most organisms. Reason: 2'—OH group present in DNA makes it less reactive. (a) Assertion and the Reason are true and the Reason is a correct explanation of the Assertion. (b) Assertion and Reason are true but the Reason is not a correct explanation of the Assertion. (c) Assertion is true but the Reason is false. (d) Assertion is false but the Reason is true. 29. In the following diagram of a human foetus within the uterus, identify 'A'. A (a) Yolk sac (b) Umbilical cord (c) Cavity of uterus (d) Placental villi NBSE 2021 6

30. Two nuclei that are situated below the egg apparatus in the central cell of female gametophyte, are called (a) central nuclei (b) nuclei (c) polar nuclei (d) nucellus 31. Choose the incorrect statement (a) The hollow foliar structure that encloses the leaf primordia in a grass embryo is called coleoptile (b) In apple, the thalamus also contributes to fruit formation and becomes edible. (c) In Zostera, the pollen grains are long and ribbon-like and released inside the water. (d) Sepals and petals are concealed in entomophilous flowers 32. Relaxin is secreted by (a) Placenta (b) Pituitary (c) Ovary (d) Chrionic villi 33. The technique in which semen from husband is artificially introduced into the vagina is called (a) Assisted Reproductive Technology (b) Intra-Vaginal Insemination (c) Infra Cytoplasmic Sperm Injection (d) Intra-Uterine Insemination 34. Which of the following is example of hormone-releasing IUDs? (a) CuT and Multiload 375 (b) LNG-20 and Progestasert (c) Lippes loop (d) Both (b) and (c) 35. The meiocyte of rice has 24 chromosomes. The number of chromosomes in its endosperm is (a) 24 (b) 12 (c) 48 (d) 36 36. Gene I has (a) two alleles IA and i (b) two alleles IB and i (c) three alleles IA, IB and i (d) none of these 37. If a plant heterozygous for tallness is selfed, the F2 generation has both tall and dwarf plants. It proves the principle of (a) dominance (b) segregation (c) independent assortment (d) incomplete dominance 38. What will be the genotype of the normally pigmented woman who if marries an albino man produces a normal offspring and an albino offspring in the ratio 1:1? (a) Homozygous (b) Heterozygous (c) Both (a) and (b) (d) Information incomplete NBSE 2021 7 [P.T.O.

39. Study the pedigree chart given below. What does it show? (a) Inheritance of a condition like phenylketonuria as an autosomal recessive trait. (b) The pedigree chart is wrong as this is not possible. (c) Inheritance of a recessive sex-linked disease like haemophilia. (d) Inheritance of a sex-linked inborn error of metabolism like phenylketonuria. 40. Gene for haemophilia is (b) X-linked dominant (a) X-linked recessive (c) Y-linked (d) autosomal 41. 1 : 2 : 1 is a ratio which is found in (b) co-dominance (a) F2 geneotypic ratio of a dihybrid cross (d) all of the above (c) incomplete dominance 42. While analysing the DNA of an organism a total number of 5386 nucleotides were found, out of which the proportion of different bases were: Adenine = 29%, Guanine = 17%, Cytosine = 32%, Thymine = 17%. Considering the Chargaff's rule it can be concluded that (a) it is a double stranded circular DNA (b) it is single stranded DNA (c) it is a double stranded linear DNA (d) no conclusion can be drawn 43. DNA is a polymer of nucleotides which are linked to each other by 3'→ 5' phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications you choose? (a) Replace purine with pyrimidines (b) Remove/replace 3' OH group in deoxyribose (c) Remove/replace 2' OH group with some other group in deoxyribose (d) Both (b) and (c) NBSE 2021 8

44. What is name of this nitrogenous base? O H3C H N O N H (a) Adenine (b) Cytosine (c) Thymine (d) Guanine 45. If Meselson and Stahl's experiment is continued for four generations in bacteria, the ratio of N15/N15:N15/N14:N14/N14 containing DNA in the fourth generation would be (a) 1 : 1 : 0 (b) 1 : 4 : 0 (c) 0 : 1 : 3 (d) 0 : 1 : 7 46. Read the following and select the correct statement/statements. (i) 23 s RNA act as a enzyme in prokaryotes. (ii) In prokaryotes DNA is monocistronic (iii) Francis Crick proposed the Central Dogma of Molecular biology. (iv) In Eukaryotes three types of RNA polymerases are present. (a) (i) only (b) (i) and (ii) (c) (i) and (iii) (d) (iii) and (iv) 47. A DNA molecule in which both strands have radioactive thymidine is allowed to duplicate / in non-radioactive thymidine. What will be the exact number of DNA molecules that contain some radioactive thymidine after 3 duplications? (a) One (b) Two (c) Four (d) Eight 48. Which is not an example of Parthenocarpy? (a) banana (b) grapes (c) pineapple (d) mango SECTION – C Section-C consists of one case followed by 6 questions linked to this case (Q.No.49 to 54). Besides this, 6 more questions are given. Attempt any 10 questions in this section. The first attempted 10 questions would be evaluated. CASE STUDY Below is the T.S. of human ovary. Identify the following in the diagram: ae b c NBSE 2021 d [P.T.O. 9

49. The structure released before formation of d is... (a) secondary oocyte (b) Ootid (c) primary picture (d) Oogonia 50. ........ is secreted by d (a) Progesterone (b) FSH (c) LH (d) Oxytocin 51. What is the condition if e is not being formed in an adult female (a) Sterility (b) High prolactin (c) Low prolactin (d) Low HCG 52. Pick the odd one out (a) a,e,c (b) d,e,c (c) e,b,c (d) d,c,b 53. Which of the following is secreted by the structure shown (a) Relaxin (b) FSH (c) LH (d) ACTH 54. Identify the figure given below. (a) Morula (b) Embryo (c) Trophoblast (d) Blastocyst 55. If one parent has sickle-cell anaemia and the other has sickle cell trait, there is ……. that their children will have sickle cell anaemia and …… will have sickle-cell trait. (a) 25 % risk, 75% risk (b) 50 % risk, 50% risk (c) 75% risk, 25% risk (d) no risk 56. The following statements are drawn as conclusions from the below data (Kenya). No. of patients with SCD No. of patients without SCD NBSE 2021 10

I. Patients with SCD (Sickle Cell Disease) are less likely to be infected with malaria. II. Patients with SCD (Sickle Cell Disease) are more likely to be infected with malaria. III. Over the years the percentage of people infected with malaria has been decreasing. IV. Year 2000 saw the largest percentage difference between malaria patients with and without SCD. Choose from below the correct alternative (a) Only I is true (b) I and IV are true (c) III and II are true (d) I and III are true 57. The enzyme which is required to join the fragments represented by ‘B’ is AB (a) Ochoa enzyme (b) Kornberg enzyme (c) Taq polymerase (d) Ligase 58. Which of the following is correct about A? Repressor m-RNA A→ (a) A is repressor (b) A is operator (c) A is structural gene (d) none of these 59. Which is not a symptom of Turner's syndrome (a) Ovaries are rudimentary (b) Lack of secondary sexual characters (c) small uterus (d) Affected females are fertile NBSE 2021 11 [P.T.O.

60. Study the following crime case in which DNA finger print of two individual suspects A and B obtained from their DNA sample and DNA sample from the crime scene has the DNA fingerprint C to answer the following question: The technique to obtain separate bands of DNA fragments (a) PCR (b) Gel electrophoresis (c) DNA fingerprint (d) none of these NBSE 2021 12