Principles of Inheritance: Class 12 Previous Year Questions

Principles of Inheritance questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1. _________ Page 19 of 24 { } 30. A student performed some crosses in plants and represented the result in the form of bar graphs as shown below. Each graph displays the phenotypic proportion of the progeny. Study the graphs and answer the questions : (a) What c…
   Board 20264 markscase-based
2. (a) What is pedigree analysis ? Mention its importance in human genetics. (2 pts.) 1 + 1 (b) Analyse the following pedigree and write the (i) Pattern of inheritance. ½ (ii) Give one example of disease showing such an inheritance pattern. ½
   Board 20263 marksshort answer
3. (a) Analyse the following two cases of sex determination in different organisms : Case I : Males have (XO) sex chromosomes and females have two copies of same sex chromosome (XX). Case II : Females have two different sex chromosomes (ZW) and males have two cop…
   Board 20262 marksshort answer
4. In the following figure, two ways of pairing of two homologous pairs of chromosomes are shown. Which of the following phenomena is expressed ? 1 (A) Linkage of genes (B) Independent assortment of genes (C) Multiple alleles (D) Incomplete dominance
   Board 20261 markMCQ
5. In a dihybrid cross, 2400 individuals are produced in F2 generation. Approximately how many will be phenotypically similar to parents ? 1 (A) 2000 (B) 1500 (C) 580 (D) 450
   Board 20261 markMCQ
6. Student to attempt either option-(A) or (B) : (A) (i) Perform a cross between two sickle cell carriers. What ratio is obtained between carrier, disease free and diseased individuals in Fi progeny ? Name the nitrogenous base substituted, in the haemoglobin mole…
   Board 20255 markslong answer
7. Study the given pedigree chart in which neither of the parents shows the trait but the trait is present in both male and female children. Parents : Generation I : Answerthe following questions : (a) Write about the trait, also explain the inheritance of such t…
   Board 20252 marksshort answer
8. Assertion (A) : When the two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations is much higher than non-parental type. Reason (R) : Higher parental gene combinations can be attributed to crossing over be…
   Board 20251 markAssertion-Reason
9. Study the cross given below : 44 + XY Parents : 44 + XX 22+XY 22 + 0 Gametes : 22+X 22 + X Offsprings Identify the abnormalities ·1' and ·2' in the offsprings of a cross done between a couple and distinguish between them. 11|Page -I : AB - II : h (/) 21. : () …
   Board 20252 marksshort answer
10. In a pedigree chartO' represents : (A) unrelated mating (B) affected individuals (C) mating between relatives (consanguineous mating) (D) Non-identical twins
    Board 20251 markMCQ
11. The phosphoester linkage in the nucleotides is between (A) phosphate group and OH of 3'C of a nucleoside. (B) phosphate group and OH of 5'C of a nucleoside. (C) phosphate group and H of 3'C of a nucleoside. (D) phosphate group and H of 5'C of a nucleoside.
    Board 20251 markMCQ
12. A woman with normal vision has a colour blind father. She marries a man with normal vision. The percentage chance of their progeny being colour blind is : (A) 25% (B) 50% (C) 75% (D) 100%
    Board 20241 markMCQ
13. (a) (i) Compare the pattern of inheritance of flower colour in garden pea plant (violet/white) with snapdragon plant (red/white) on the basis of the following : 4 (1) F1 phenotypic expression; (2) expected phenotypic and genotypic expression of F2 generation; …
    Board 20245 markslong answer
14. Although Haemophilia and sickle cell anemia are two blood related Mendelian disorders, yet, they differ in their pattern of inheritance. State any two differences.
    Board 20242 marksshort answer
15. The type of bond represented by the dotted line in a schematic polynucleotide chain is : (A) Hydrogen bond (B) Peptide bond (C) N-glycosidic linkage (D) Phosphodiester bond 6 7. {ZåZ{b{IV _| go {H$g àH$ma H$s n[apñW{V`m|/amoJ _| _mZd eara _| _mñQ> H$mo{eH$mAm|…
    Board 20241 markMCQ
16. Assertion (A) : Linked genes do not show dihybrid F2 ratio 9 : 3 : 3 : 1. Reason (R) : Linked genes do not undergo independent assortment.
    Board 20241 markAssertion-Reason
17. Match the items in Column I with those in Column II and select the correctly matched option from those given below : Column I Cross Column II Phenotypic Ratio 1. Mendelian monohybrid (i) 1 : 2 : 1 (F2) 2. Mendelian dihybrid (ii) 1 : 1 3. Incomplete dominance (…
    Board 20241 markMCQ
18. Which one of the following is not a feature of plasmids ? (A) Circular (B) Self-replicating (C) Single stranded (D) Extra-chromosomal
    Board 20241 markMCQ
19. JJJJ Page 18 27. (H$) AmYw{ZH$ `wJrZ _mZd (dV©_mZ `wJ Ho$ _mZd) Ho$ Eogo Xmo ZadmZaJU (àmB_oQ²>g) nyd©Om| Ho$ Zm_ {b{IE Omo bJ^J 15 {_{b`Z df© nyd© {dÚ_mZ Wo & (I) Ordmí_ gmú`m| Ho$ AZwgma {H$g g_`-H$mb _| Am¡a H$hm± ahVo Wo ? (J) VWm Ho$ ~rM Xmo A§Va {b{IE & …
    Board 20233 marksshort answer
20. JJJJ Page 25 29. The following pedigree chart shows the inheritance of a genetic disorder up to three generations of a family. Observe the chart and answer the questions that follow. (i) Is the disease sex-linked or autosomal as per the chart ? Give reasons in…
    Board 20234 marksshort answer

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