Comprehensive CBSE Objective Type Question Bank Biology (Term -1)

Biology



Comprehensive CBSE Objective Type Question Bank Biology Term–I (FOR CLASS XII) (According to the Latest CBSE Examination Pattern) By Dr. J.P. Sharma M.Sc., Ph.D., FISST Ex-Head, Deptt. of Botany Hindu College, Sonepat (M.D. University, Rohtak) Haryana   LAXMI PUBLICATIONS (P) LTD (An ISO 9001:2015 Company) BENGALURU • CHENNAI • GUWAHATI • HYDERABAD • JALANDHAR KOCHI • KOLKATA • LUCKNOW • MUMBAI • RANCHI NEW DELHI

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Contents Chapters Pages Unit I Reproduction 1–44 Chapter 1. Sexual Reproduction in Flowering Plants 3–14 Chapter 2. Human Reproduction 15–34 Chapter 3. Reproductive Health 35–44 Unit II Genetics and Evolution 45–82 Chapter 4. Principles of Inheritance and Variation 47–65 Chapter 5. Molecular Basis of Inheritance 66–82



Syllabus Class XII (Code N. 044) (2021-22) Term–I Theory EVALUATION SCHEME Marks Units 15 VI Term–I 20 VII Reproduction: Chapter–2, 3 and 4 35 Genetics and Evolution: Chapter–5 and 6 Total THEORY TERM-I Unit-VI Reproduction Chapter-2: Sexual Reproduction in Flowering Plants Flower structure; development of male and female gametophytes; pollination–types, agencies and examples; outbreeding devices; pollen-pistil interaction; double fertilization; post fertilization events–development of endosperm and embryo, development of seed and formation of fruit; special modes–apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit formation. Chapter-3: Human Reproduction Male and female reproductive systems; microscopic anatomy of testis and ovary; gametogenesis–spermatogenesis and oogenesis; menstrual cycle; fertilisation, embryo development upto blastocyst formation, implantation; pregnancy and placenta formation (elementary idea); parturition (elementary idea); lactation (elementary idea). Chapter-4: Reproductive Health Need for reproductive health and prevention of Sexually Transmitted Diseases (STDs); birth control–need and methods, contraception and medical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive technologies–IVF, ZIFT, GIFT (elementary idea for general awareness). Unit-VII Genetics and Evolution Chapter-5: Principles of Inheritance and Variation Heredity and variation: Mendelian inheritance; deviations from Mendelism–incomplete dominance, co-dominance, multiple alleles and inheritance of blood groups, pleiotropy;

elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; Sex determination–in human being, birds and honey bee; linkage and crossing over; sex linked inheritance–haemophilia, colour blindness; Mendelian disorders in humans– thalassemia; chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes. Chapter-6: Molecular Basis of Inheritance Search for genetic material and DNA as genetic material; Structure of DNA and RNA; DNA packaging; DNA replication; Central Dogma; transcription, genetic code, translation; gene expression and regulation–lac operon; Genome, Human and rice genome projects; DNA fingerprinting.

Unit I Reproduction 1. Sexual Reproduction in Flowering Plants 2. Human Reproduction 3. Reproductive Health



Chapter-1 Sexual Reproduction in Flowering Plants Multiple Choice Questions In each of the following questions only one option is correct. Select the correct option. 1. The study of formation, growth and development of a new individual from an egg is known as (a) Cytology (b) Embryology (c) Histology (d) Genetics 2. A leaf cell of a flowering plant has 22 chromosomes, then the number of chromosome would be (a) 11 in gametes (b) 22 in gametes (c) 44 in embryo (d) 11 in a cell of stem 3. The nuclei of the sperm and egg fuse as a result of (a) Base pair relation of DNA and RNA (b) Formation of hydrogen bonds (c) Mutual attraction caused by differences in electrical charges (d) Attraction of protoplasts of the egg and the sperm 4. The best example of polyembryony is (a) Cocos (b) Citrus (c) Capsicum (d) Cycas 5. The micropyle in a seed helps in the entry of (a) Water (b) Pollen tube (c) Male gamete (d) None 6. How many meiotic divisions are necessary for the formation of 100 grains of wheat? (a) 100 (b) 125 (c) 25 (d) 50 7. The embryo sac of a typical dicot at the time of fertilization is (a) 8-celled (b) 7-celled (c) 6-celled (d) 5-celled 8. Even after killing the generative cell with a laser beam, the pollen grain of a flowering plant germinates and produces normal pollen tube because (a) Laser beam stimulate pollen germination and pollen tube growth (b) Laser beam does not damage the region from which pollen tube emerges (c) The contents of the killed generative cell permit germination and pollen growth (d) The vegetative cell has not been damaged. 9. A bisexual flower which never opens in its life span is called (a) Homogamous (b) Heterogamous (c) Dichogamous (d) Cleistogamous

4 Biology-XII 10. The position of shoot apex in monocot embryo is (a) Basal (b) Lateral (c) Terminal (d) Sub-terminal 11. Scutellum is a (b) Shield shaped cotyledon of monocots (a) Endosperm of gymnosperm (c) Protective covering of radicle (d) Protective covering of plumule. 12. In which one of the following plants is the oil stored in the endosperm ? (a) Groundnut (b) Sesame (c) Coconut (d) Soyabean 13. In a flowering plant, archesporium gives rise to (a) Only tapetum and sporogenous cells (b) Only the wall of the sporangium (c) Both wall and the sporogenous cells (d) Wall and the tapetum 14. An ovule which becomes curved so that the nucellus and embryo lie at right angles to the funicle is (a) Campylotropous (b) Anatropous (c) Orthotropous (d) Hemianatropous 15. Heterozygosity is produced following (d) Cleistogamy (a) Xenogamy (b) Geitonogamy (c) Autogamy 16. Palynology is the study of (b) Pollen morphology (a) Pollen germination (c) Pollen development (d) Arrangement of pollen grains 17. Sexual reproduction of flowering plants was discovered by (a) Strasburger (b) Nawaschin (c) Maheswari (d) Camerarius 18. Embryo sac is (b) Microsporangium (a) Microgametophyte (c) Megagametophyte (d) Megasporangium. 19. Formation of embryo directly from nucellus and integument is (a) Adventive polyembryony (b) Apogamy (c) Apospory (d) Apomixis 20. Egg apparatus consists of (b) Polar nuclei (a) Egg and antipodals (c) Egg (d) Egg and synergids 21. Pollen grains are able to tolerate extremes of temperature and desiccation as its exine is made of (a) Sporopollenin (b) Suberin (c) Cutin (d) Callose 22. The function of guiding and attracting pollen tube is done by (a) Egg cell (b) Antipodal cells (c) Secondary nucleus (d) Synergids

Sexual Reproduction in Flowering Plants 5 23. Effect of pollen on character of pericarp and seed coat is (a) Xenia (b) Metaxenia (c) Chimera (d) Ruminate endosperm 24. Intraspecific incompatibility is overcome by (a) Self-pollination (b) Wetting of anthers (c) Wetting of stigmas (d) Mixed pollination 25. Secondary nucleus present in the middle of embryo sac is (a) Haploid (b) Diploid (c) Triploid (d) Tetraploid 26. Largest cell of ovule is (b) Megaspore mother cell (a) Antipodal cell (c) Central cell (d) Synergid 27. A diploid female plant is crossed with tetraploid male. The ploidy of endosperm will be (a) Diploidy (b) Triploidy (c) Tetraploidy (d) Pentaploidy 28. Entry of pollen tube through chalazal end is (a) Syngamy (b) Porogamy (c) Basigamy (d) Mesogamy. 29. Double fertilization involves (a) Fertilization on an egg by two male gametes. (b) Fertilization of egg and central cell by two sperms brought by same pollen tube. (c) Fertilization of two eggs in the same embry sac by two sperms bought by one pollen tube. (d) Fertilization of egg and central cell by two sperms brought by two different pollen tubes 30. Arrangement of nuclei in normal dicot embryo sac is (a) 3 + 3 + 2 (b) 2 + 4 + 2 (c) 3 + 2 + 3 (d) 2 + 3 + 3 31. Endosperm is consumed by developing embryo in the seeds of (a) Maize (b) Coconut (c) Castor (d) Pea 32. Which one of the following is resistant to enzyme action ? (a) Leaf cuticle (b) Cork (c) Wood fibre (d) Pollen exine 33. Which one of the following pairs of plant structures has haploid number of chromosomes? (a) Egg nucleus and secondary nucleus. (b) Megaspore mother cell and antipodal cells. (c) Egg cell and antipodal cells. (d) Nucellus and antipodal cells.

6 Biology-XII 34. What does the filiform apparatus do at the entrance into ovule (a) It guides pollen tube from a synergid to egg. (b) It helps in the entry of pollen tube into a synergid. (c) It prevents entry of more than one pollen tube into the embryo sac. (d) It brings about opening of the pollen tube 35. Unisexuality of flowers prevents (b) Autogamy but not geitonogamy (a) Autogamy and geitonogamy (c) Both geitonogamy and xenogamy (d) Geitonogamy but not xenogamy 36. The scutellum observed in a grain of wheat or maize is comparable to which part of the seed in other dicotyledonous? (a) Aleurone layer (b) Plumule (c) Cotyledon (d) Endosperm 37. Wind pollinated flowers are (a) large producing abundant nector and pollen (b) small, producing nector and dry pollen (c) small, brightly coloured, producing large number of pollen grains. (d) small, producing large number of dry pollen grains. 38. Apomictic embryos in Citrus arise from (a) Antipodal cells (b) Diploid egg (c) Synergids (d) Maternal sporophytic tissue 39. Nucellar polyembryony is reported in species of (a) Brassica (b) Citrus (c) Gossypium (d) Triticum 40. Filiform apparatus is a characteristic feature of (a) Zygote (b) Suspensor (c) Egg (d) Synergids 41. What would be the number of chromosomes of the aleurone cells of a plant with 42 chromosomes in its root tip cells? (a) 21 (b) 42 (c) 63 (d) 84 42. Wind pollination is common in (a) Orchids (b) Legumes (c) Lilies (d) Grasses 43. In which one of the following pollination is autogamous? (d) Chasmogamy (a) Cleistogamy (b) Geitonogamy (c) Xenogamy 44. In a flowering plant, the pollen tube first arrives in (a) Egg (b) An antipodal cell (c) A synergid (d) Central cell 45. Long ribbon-like pollen grains are seen in some (a) Aquatic plants (b) Wind pollinated grasses (c) Gymnosperms (d) Bird pollinated flowers 46. Scutellum in a caryopsis represents (a) Outermost layer of endosperm (b) A sheath that protects the radicle

Sexual Reproduction in Flowering Plants 7 (c) The place where seed is attached to raphe (d) A colyledon 47. Both autogamy and geitonogamy are prevented in: (a) Papaya (b) Cucumber (c) Castor (d) Maize 48. Even in absence of pollinating agents seed setting is assured in: (a) Commelina (b) Zostera (c) Salvia (d) Fig 49. The coconut water and the edible part of coconut are equivalent to: (a) Endosperm (b) Endocarp (c) Mesocarp (d) Embryo 50. An organic substance that can withstand environmental extremes and cannot be degraded by any enzyme is: (a) Cuticle (b) Sporopollenin (c) Lignin (d) Cellulose 51. Which one of the following statements is wrong? (a) When pollen is shed at two-celled stage, double fertilisation does not take place (b) Vegetative cell is larger than generative cell (c) Pollen grains in some plants remain viable for months (d) Intine is made up of cellulose and pectin 52. Plants with ovaries having only one or a few ovules are generally pollinated by (a) Bees (b) Butterflies (c) Birds (d) Wind 53. Perisperm differs from endosperm in (a) its formation by fusion of secondary nucleus with several sperms. (b) being haploid tissue. (c) having no reserve food. (d) being a diploid tissue. 54. Megasporangium is equivalent to (a) Ovule (b) Embryo sac (c) Fruit (d) Nucellus 55. Advantage of cleistogamy is (b) Higher genetic variability (a) Vivipary (c) More vigorous offspring (d) No dependence on pollinators 56. Which one of the following statements is correct? (a) Tapetum nourishes the developing pollen. (b) Hard outer layer of pollen is called intine. (c) Sporogenous tissue is haploid. (d) Endothecium produces the microspores. 57. Non-endospermic seeds are found in (a) Bean (b) Gram (c) Pea (d) All the above 58. Endosperm completely consumed by the developing embryo before seed maturation in : (a) Pea, groundnut and caster (b) Groundnut, bean and coconut (c) Pea, groundnut and bean (d) None of these

8 Biology-XII 59. The body of ovule fused with funicle is called (a) Integument (b) Hilum (c) Micropyle (d) Chalaza 60. Male gametophyte with least number of cells is present in (a) Lilium (b) Pinus (c) Pteris (d) Funaria 61. Non-albuminous seeds is produced in (b) Pea (a) Wheat (c) Maize (d) Castor 62. Function of filiform apparatus is to (a) Produce nectar (b) Guide the entry of pollen tube (c) Recognize the suitable pollen at stigma (d) Stimulate division of generative cell 63. Which one of the following statements is correct? (a) A proteinaceous aleurone layer is present in maize grain. (b) A sterile pistil is called a staminode. (c) The seed in grasses is not endospermic. (d) Mango is a parthenocarpic fruit. 64. Pollen tablets are available in the market for (a) Supplementing food (b) Ex-situ conservation (c) In vitro fertilization (d) Breeding programmes 65. Transmission tissue is characteristic feature of (a) Dry stigma (b) Wet stigma (c) Hollow style (d) Solid style 66. Male gametophyte in angiosperms produces : (a) Single sperm and a vegetative cell (b) Single sperm and two vegetative cell (c) Three sperms (d) Two sperms and a vegetative cell 67. Coconut water from a tender coconut is (a) Free nuclear endosperm (b) Inner most layer of seed coat (c) Degenerated nucellus (d) Immature embryo Answers 1. (b) 2. (a) 3. (d) 4. (b) 5. (a) 6. (b) 7. (b) 8. (d) 9. (d) 10. (b) 11. (b) 12. (c) 13. (c) 14. (d) 15. (a) 16. (a) 17. (d) 18. (c) 19. (a) 20. (d) 21. (a) 22. (d) 23. (b) 24. (d) 25. (b) 26. (c) 27. (c) 28. (c) 29. (b) 30. (c) 31. (d) 32. (d) 33. (c) 34. (b) 35. (b) 36. (c)

Sexual Reproduction in Flowering Plants 9 37. (d) 38. (d) 39. (b) 40. (d) 41. (c) 42. (d) 43. (a) 44. (c) 45. (a) 46. (d) 47. (a) 48. (a) 49. (a) 50. (b) 51. (a) 52. (d) 53. (d) 54. (d) 55. (d) 56. (a) 57. (d) 58. (c) 59. (b) 60. (a) 61. (b) 62. (b) 63. (a) 64. (a) 65. (d) 66. (d) 67. (a) Assertion-Reason Type Questions In the following questions a statement of Assertion (A) is followed by a statement of Reason (R). — If both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion, then mark (a). — If both Assertion and Reason are true, and the Reason is not the correct explanation of the Assertion, then mark (b). — If Assertion is true statement but Reason is false, then mark (c). — If both Assertion and Reason are false statements, then mark (d). 1. A. Entomophilous plants produce less pollens than anemophilous plants. R. Pollination is directional in entomophilous plants. 2. A. Triple fusion results in vegetative fertilization of angiosperms. R. It combine one male gamete with two synergid. 3. A. Red coloured flowers attracts butterflies and wasps, but not bees. R. Bees are colour blind to red. 4. A. In angiosperms, the ovule develops into a seed after fertilization. R. Fertilization is not essential for the development of trunk. 5. A. In apomixis, plants of new genetic sequences are produced. R. In apomixis, individuals of same genetic sequences meet. 6. A. Megaspore mother cell undergoes meiosis to produce four megaspores. R. Megaspore mother cell and megaspores are both haploid. 7. A. Insect visit flowers to collect honey. R. Attraction to flower prevents the insects from damaging others. Answers 1. (a) 2. (c) 3. (a) 4. (b) 5. (d) 6. (c) 7. (d)

10 Biology-XII Matching Type Questions In the following questions match the items in Column I with the items in Column II. An item in Column I may match with more than one items in Column II. Match the Terms of Column I with Terms of Column II: I. Column I Column II (a) Zygote (i) Vallisneria (b) Parthenocarpy (ii) Sunflower (c) Bird pollination (iii) Groundnut (d) Hydrophily (iv) Embryo (e) Capitulum (v) Edible banana (f) Non-endospermous seed (vi) Red silk cotton II. Column I Column II (a) Double fertilization (i) Micropropagation (b) Megaspore (ii) Seed (c) Asexual reproduction (iii) Angiosperms (d) Ovule (iv) Embryo sac (e) Plant tissue culture (v) Pericarp (f) Ovary wall (vi) Apomixis Answers I. (a)–(iv) (b)–(v) (c)–(vi) (d)–(i) (e)–(ii) (f)–(iii) II. (a)–(iii) (b)–(iv) (c)–(vi) (d)–(ii) (e)–(i) (f)–(v) Very Short Answer Type Questions 1. Which are the nuclei that fuse to form primary endosperm nucleus? 2. Name a parthenocarpic fruit. 3. What is funiculus? 4. Water lily is an aquatic plant, yet it shows entomophily. Why? 5. Name the weed that has become ubiquitous in occurrence in India and causes pollen allergy. 6. Name the most resistant biological material known. 7. The microscopic pollen grains of the past are obtained as fossils. Mention the characteristic of the pollen grains that makes it happen.

Sexual Reproduction in Flowering Plants 11 8. Mention the pollinating agent of an inflorescence of small dull coloured flowers with well exposed stamens and large feathery stigma. Give any one characteristic of pollen grains produced by such flowers. 9. Name the type of flower which favours cross pollination. 10. Why is bagging of the emasculated flowers essential during hybridization experiments. 11. The meiocyte of rice has 24 chromosomes. How many chromosomes are present in its endosperm? 12. The following statements (i) (ii) and (iii) seems to describe the water-pollinated submerged plants. Which one of these statement is incorrect? (i) The flowers do not produce nectar. (ii) The pollen grains have mucilaginous covering. (iii) The brightly coloured female flowers have long stalk to reach the surface. 13. Pea flowers produce assured seed sets. Give a reason. 14. A bilobed, dithecons anther has 100 microspore mother cells per microsporangium. How many male gametophytes this anther can produce? 15. An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give one reason. 16. How do the pollen grains of Vallisneria protect themselves? 17. An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give any one reason. Answers 1. One male nucleus and two polar nuclei 2. Banana/Grape. 3. Stalk line structure on which ovules borne. 4. Water lily bears flower above the surface of water. 5. Parthenium (Carrot grass). 6. Sporopollenin. 7. The exine of the pollen grain is made up of most resistant organic material called sporopollenin. 8. Wind; Pollen grains are light and non-sticky. 9. Dioecy. 10. To prevent contamination of its stigma from unwanted pollens. 11. 36. 12. The brightly coloured female flowers have long stalk to reach to the surfrace. 13. Pea flowers are cleistogamous hence show autogamy and produce assured seed set. 14. 100 × 4 = 1600. 15. The developing pollen grains fail to get nourishment, hence become non-viable.

12 Biology-XII 16. Pollen grains in Vallisneria are protected from wetting by mucilaginous covering. 17. Normal pollen grains will not be formed because of failure of their nourishment due to malfunctioning of tapetum. Fill in the Blanks Fill in the following blanks with appropriate items: 1. A flower with inferior ovary is called ...... . 2. In bean seed, the food is stored in ...... . 3. The ovary wall develops into a fruit wall called ...... . 4. Pollination by bats is called ...... . 5. Protective sheath above the radicle in maize grain is known as ...... . 1. Epigynous Answers 3. Pericarp 4. Chiropterophily 2. cotyledon 5. Coleorhiza. True/False Statements State whether the following statements are true or false: 1. In apomixis, the new individuals are genetically dissimilar to the parent producing them. 2. One major drawback of hybrid cultivation is that hybrid seeds have to be produced every year. 3. In some varieties of Citrus and Mango, some nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into many embryos. 4. The fruit which is derived from ovary of the flower and not associated with any non- carpellary part is called false fruit. 5. Apple and fig are true fruits as they have fleshy receptacle as the main edible part.F 6. The seeds such as bean, pea, gram etc. in which the endosperm is used up are called exalbuminous. 7. Removal of stamens or anthers of a bisexual flower without affecting the female reproductive organs is called emasculation. 8. There is a very close obligatory symbiotic relationship between Yacca plant and its insect pollinator Colpa aurea (a hairy wasp). 9. Zostera marina is a totally submerged marine angiosperm which is pollinated by birds.

Sexual Reproduction in Flowering Plants 13 10. The term protogyny refers to the condition when androecium mature earlier than the gynoecium of the same flower. 11. The condition when bisexual, inconspicuous, colourless flowers never open to esure complete self pollination, is called cleistogamy. 12. Out of the 7 cells of mature female gametophyte, the central cell fuses with one male gamete to form triploid primary endosperm nucleus. 13. Entomophily is the transfer of pollen grains from anther to stigma through the agency of bats. 14. Ornithophilous flowers are large-sized, have tubular of funnel shaped coloured corolla and produce nectar to attract birds for pollination. 15. Calyx and corolla of a typical angiospermic flower are non-essential whorls. 16. The gynoecium represents the male reproductive organ of the plant. 17. Stamens are modified leaves (or microsporophylli) concerned with the production of microspores (or pollen grains). 18. Flowers are modifications of shoot to perform the function of sexual reproduction. 19. Exine is the outer layer of pollen grain chiefly composed of pecto-cellulose. 20. Approximately 70% plant species shed their pollen at the two-celled stage. 1. False 2. True Answers 5. False 6. True 7. True 8. True 3. True 4. False 11. True 12. True 13. False 14. True 9. False 10. False 17. True 18. True 19. False 20. True 15. True 16. False Case Study Based MCQs I. There was an article publiced in a newspaper on pistil subject. Study the article and answer the following questions. Each pistil has three parts—stigma, style and ovary. The stigma is the distal bulbous part, which serves as a landing platform for pollen grains. The style is cylindrical part below the stigma. The basal swollen part of the pistil is the ovary. There is a cavity inside the ovary called locule or ovarian cavity. Inside the ovarian cavity, megasporangia, commonly called ovules are borne on cushion like tissue called placenta. The number of ovules in an ovary may be one (e.g., wheat, paddy, mango) to many (e.g., lemon, papaya, water melon and orchids). 1. How many parts are these in each pistil? (a) One (b) Two (c) Three (d) Four 2. Name each part of the pistil. (a) Stigma (b) Style (c) Ovary (d) All of the above

14 Biology-XII 3. Which part of pistil is serves as a landing platform for pollen grains? (a) Stigma (b) Style (c) Ovary (d) None of these 4. Which part of pistil is cylindrical? (a) Ovary (b) Style (c) Stigma (d) All of the above 5. Cavity inside the ovary called ............ (a) locale (b) ovarian cavity (c) Both (a) and (b) (d) None of these II. There was an article publiced in a Magazine. Study the article and answer the following questions. The events that occur in the flower after double fertilization are called post- fertilization events. These include the development of endosperm and embryo, maturation of ovule(s) into seed(s) and ovary into fruit. After fertilization the sepals, petals, stamens,style and stigma usually withered and fall off. The calyx may persist (e.g., tomato, brinjal) and even show growth (e.g., Physalis). The zygote undergoes a number of mitotic divisions and forms a multicellular embryo. The primary endosperm nucleus also undergo mitotic divisions to form a food laden tissue called endosperm. The antipodal cells have no special function and perish after fertilization. The ovules mature into seeds and the ovary containing the ovules enlarges and forms the fruit. The above mentioned changes can be studied under the following headings: 1. Endosperm formation, 2. Embryo formation, 3. Seed formation and 4. Fruit formation. 1. The events that occur in the flower after double fertilization are called: (a) post-fertilization events (b) future-fertilization events (c) pre-fertilization events (d) None of these 2. After which events the sepals, petals, stamens, style and stigma usually withered and fall off? (a) Hybridisation (b) Fertilization (c) Fusion (d) None of these 3. Food laden tissue are called: (b) zyote (a) endosperm (c) Both (a) and (b) (d) None of these 4. The above mentioned changes can be studied under: (a) endospherm formation (b) embryo formation (c) seed and fruit formation (d) All of these 5. Which cell have no special function and perish after fertilization? (a) Antipodal cells (b) Ovary cells (c) Triploid (d) None of these Answers I. 1. (c) 2. (d) 3. (a) 4. (b) 5. (c) II. 1. (a) 2. (b) 3. (a) 4. (d) 5. (a)

Unit II Genetics and Evolution 4. Principles of Inheritance and Variation 5. Molecular Basis of Inheritance



Chapter-4 Principles of Inheritance and Variation Multiple Choice Questions In each of the following questions only one option is correct. Select the correct option. 1. A plant is heterozygous and is designated Bb, it produces two kinds of gametes B and b. The possibility of b gamete fertilizing B or b is (a) 1 (b) 1 24 (c) 1 (d) 0 11 2. What will be the genetic constitution of the offspring of a cross of individuals heterozygous (Aa) for an allele ? (a) AA (b) aa (c) AA : 1 aa (d) 1 AA : 1 Aa : 1 aa. 2 4 24 3. A cross of F1 with the recessive parent is known as (a) back cross (b) test cross (c) hybrid cross (d) double cross. 4. The percentage of ab gametes produced by AaBb parent will be (a) 12.5 (b) 25 (c) 50 (d) 75. 5. F1 Plants are (b) homozygous (a) heterozygous (c) hemizygous (d) dizygous. 6. From a cross AaBB × aaBB following genotypic ratio will be obtained in F1 generation (a) 1 AaBB : 3 aaBB (b) 3 AaBB : 1 aaBB (c) all AaBB and no aaBB (d) 1 AaBB : 1 aaBB. 7. Mendel’s law apply only when (a) Characters are linked (b) Parents are pure breeding (c) F1 monohybrid ratio shows two types of individuals (d) First pair of contrasting characters is dependent upon other pairs 8. Segregation of Mendelian factors (no linkage, no crossing over) occurs during (a) Anaphase I (b) Anaphase II (c) Diplotene (d) Metaphase I

48 Biology-XII 9. An allele is dominant if it is expressed in (a) Both homozygous and heterozygous condition (b) Second generation (c) Heterozygous combination (d) Homozygous combination 10. Percentage of heterozygous individuals obtained from selfing Rr individual is (a) 100 (b) 75 (c) 50 (d) 25 11. A woman with albinic father marries an albinic man. The proportion of her progeny is (a) 2 normal : 1 albinic (b) All normal (c) All albinic (d) 1 normal : 1 albinic 12. The process of mating between closely related individuals is (a) Self-breeding (b) Inbreeding (c) Hybridization (d) Heterosis 13. The father has blood group AB and mother O. The child is supposed to have which of the following groups ? (a) A or B (b) A only (c) B or O (d) B only 14. A blood group has agglutinogen (b) On RBCs (a) In serum (c) In plasma (d) In haemoglobin 15. In humans, height shows a lot of variation. It is an example of (a) Multiple alleles (b) Pleiotropic inheritance (c) Polygenic inheritance (d) Pseudoalleles 16. Gene with multiple effect is (b) Pleiotropic (a) Codominant (c) Epistatic (d) Supplementary 17. How many different types of genetically different gametes will be produced by a heterozygous plant having the genotype AABbCc ? (a) Two (b) Four (c) Six (d) Nine 18. Which one of the following traits of garden pea studied by Mendel was a recessive ? (a) Round seed shape (b) Axial flower position (c) Green seed colour (d) Green pod colour 19. The gene controlling the seven pea characters studied by Mendel are now known to be located on how many different chromosomes (a) Four (b) Seven (c) Six (d) Five 20. A haemophilic man marries a normal homozygous woman. What is the probability that their son will be haemophilic ? (a) 100% (b) 75% (c) 50% (d) 0%

Principles of Inheritance and Variation 49 21. A family of five daughters only, is expecting sixth issue, the chance of its being a son is (a) Zero (b) 25% (c) 50% (d) 100%. 22. Which one can have sex chromosomes? (b) Bisexual flower (a) Unisexual flower (c) Unisexual plant (d) Hermophrodite plant 23. Genes located on mitochondrial DNA (a) Generally show maternal inheritance (b) Are always inherited from male parent (c) Show biparental inheritance (d) Are not inherited like the nuclear genes 24. Different mutations referrable to the same locus of a chromosome give rise to (a) Multiple alleles (b) Pseudoalleles (c) Polygenes (d) Oncogenes 25. In Klinefelter’s syndrome, the sex chromosome complement is (a) XXY (b) XO (c) XYY (d) XXX. 26. A human male has one barr body in his somatic cell nuclei. The chromosome constitution must be (a) XO (b) XYY (c) XXY (d) XXXY 27. Human syndrome with tall stature, mental defects and antisocial behaviours is (a) XYY (b) Klinefelter’s syndrome (c) Down’s syndrome (d) Turner’s syndrome 28. XXY sex chromosome complement occurs in (a) Super females (b) Down’s syndrome (c) Turner’s syndrome (d) Klinefelter’s syndrome 29. A syndrome in which human has an extra X chromosome is (a) Down’s syndrome (b) Klinefelter’s syndrome (c) Turner’s syndrome (d) Bleeder’s syndrome 30. A pregnant woman underwent amniocentesis. An extra barr body is present in the embryo. Syndrome likely to occur in child is (a) Klinefelter’s syndrome (b) Down’s syndrome (c) Edward’s syndrome (d) Patau’s syndrome 31. Which would result in haemolysis in foetus ? (a) AO incompatibility (b) AB incompatibility (c) Rh incompatibility (d) All of these.

50 Biology-XII 32. The linkage map of X chromosome of fruit fly has 66 units with yellow body gene (y) at one end and bobbed hair (b) gene at the other end. The recombination frequency between these two genes (y and b) should be (a) 100% (b) 66% (c) > 50% (d) ≤ 50% 33. In recent years, DNA sequences (nucleotide sequence) of mt-DNA and Y chromosomes were considered for the study of human evolution, because (a) they can be studied from the samples of fossil remains (b) they are small and easy to study (c) they are uniparental in origin and do not take part in recombination. (d) their structure is known in greater detail 34. In ‘Drosophila’ the sex is determined by (a) whether the egg is fertilized or develops parthenogenetically (b) the ratio of number of X chromosomes to the sets of autosomes (c) X and Y chromosomes (d) the ratio of pairs of X-chromosomes to the pairs of autosomes 35. Christmas disease is another name for (b) Haemophilia-B (a) Sleeping sickness (c) Hepatitis-B (d) Down’s syndrome 36. When a cluster of genes show linkage behaviour they (a) induce cell division (b) do not show chromosome map (c) show recombination during meiosis (d) do not show independent assortment.  (CBSE 2003) 37. Down’s syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder? (a) 25% (b) 100% (c) 75% (d) 50% 38. Scientist who was awarded Nobel prize for finding genes to be linearly arranged on chromosomes was (a) Punnet (b) Morgan (c) Wolf (d) Swamerdan 39. Number of Barr bodies in XXXX female would be (a) 4 (b) 3 (c) 2 (d) 1 40. Find out the mismatch (a) Klinefelter’s syndrome-XO (b) Haemophilia-sex linked (c) Down’s syndrome-Autosomal aneuploidy (d) Turner’s syndrome-Female with retarded sexual developement 41. A diploid cell is treated with colchicine. It becomes (a) Diploid (b) Monoploid (c) Triploid (d) Tetraploid

Principles of Inheritance and Variation 51 42. A plant with genotype AABbCC is selfed. F2 Phenotypic ratio would be (a) 9 : 3 : 3 : 1 (b) 3 : 1 : 1 : 1 (c) 1 : 1 (d) 3 : 1 43. One of the genes present exclusively on the X-chromosome in humans in concerned with (a) Baldness (b) Facial hair/moustaches in males (c) Red-green colour blindness (d) Night blindness 44. How many types of gametes are found in F1 progeny of cross AABBCC and aabbcc. (a) 3 (b) 8 (c) 27 (d) 64 45. A person with blood group A possesses (b) Antigen B and antibody a (a) Antigen A and antibody B (c) Antigen A and antibody b (d) No antigen and no antibody 46. Out of a population of 800 F2 individuals of a cross between yellow round and green wrinkled Pea plants, the number of yellow wrinkled seeds would be (a) 150 (b) 200 (c) 400 (d) 800 47. Cri du chat is due to chromosomal aberration called (a) Duplication (b) Deletion (c) Inversion (d) Translocation. 48. Test cross is crossing between (b) Genotype with recessive trait (a) Genotype with dominant trait (c) F1 hybrid with double recessive (d) Two F1 hybrids 49. Haploids are more suitable for mutation studies than the diploids. This is because (a) All mutations, whether dominant or recessive are expressed in haploids. (b) Haploids are reproductively more stable than diploids. (c) Mutagens penetrate in haploids more effectively than diploids. (d) Haploids are more abundant in nature than diploids. 50. Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/linkage ? (a) Down syndrome—44 autosomes + XO (b) Klinefelter syndrome—44 autosomes + XXY (c) Colour blindness—Y-linked (d) Erythroblastosis foetalis—X linked. 51. Sickle cell anemia is (a) characterized by elongated sickle like RBCs with a nucleus. (b) an autosomal linked dominant trait. (c) caused by substitution of valine by glutamic acid in the beta globin chain of a haemoglobin. (d) caused by a change in a single base pair of DNA

52 Biology-XII 52. Study the pedigree chart given below: What does it shows? (a) Inheritance of a recessive sex-linked disease like haemophilia. (b) Inheritance of a sex-linked inborn error of metabolism like phenylketonuria. (c) Inheritance of a condition like phenylketonuria as an autosomal recessive trait. (d) The pedigree chart is wrong as this is not possible. 53. The most popularly known blood grouping is the ABO grouping. It is named ABO and not ABC, because ‘O’ in it refers to having (a) no antigens besides A and B on RBCs. (b) Other antigens besides A and B on RBCs. (c) Over-dominance of this type on the genes for A and B types. (d) One antibody only—either anti-A or anti-B on the RBCs. 54. Select the incorrect statement from the following : (a) Baldness is a sex-limited trait. (b) Linkage is an exception to the principle of independent assortment in heredity. (c) Galactosemia is an inborn error of metabolism. (d) Small population size results in random genetic drift in a population. 55. Polyploidy can be produced artificially by (a) Colchicine (b) Inbreeding (c) Line breeding (d) Self-pollination 56. Alzheimer disease in humans is associated with the deficiency of (a) dopamine (b) glutamic acid (c) acetylcholine (d) gamma aminobutyric acid (GABA) 57. ABO blood groups in humans are controlled by the gene I. It has three alleles IA, IB and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur ? (a) Four (b) Two (c) Three (d) One 58. The genotype of a plant showing the dominant phenotype can be determined by (a) Pedigree analysis (b) Back cross (c) Test cross (d) Dihybrid cross

Principles of Inheritance and Variation 53 59. Which one of the following symbols and its representation, used in human pedigree analysis is correct ? (a) = Unaffected female (b) = Male affected (c) = Mating between relatives (d) = Unaffected male. 60. Which one of the following cannot be explained on the basis of Mendel’s Law of Dominance ? (a) Alleles do not show any blending and both the characters recover as such in F2 generation (b) Factors occur in pairs (c) The discrete unit controlling a particular character is called a factor (d) Out of one pair of factors one is dominant, and the other recessive. 61. A cross in which an organism showing a dominant phenotype is crossed with the recessive parent in order to know its genotype is called (a) Dihybrid cross (b) Monohybrid cross (c) Back cross (d) Test cross. 62. The fruit fly (Drosophila melanogaster) was found to be very suitable for experimental verification of chromosomal theory of inheritance by Morgan and his colleagues because. (a) it completes life cycle in about two weeks (b) it reproduces parthenogenetically (c) a single mating produces two young flies (d) smaller female is easily recognisable from larger male 63. In Antirrhinum two plants with pink flowers were hybridized. The F1 plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization? Red flower colour is determined by RR, and white by rr genes. (a) rr (b) rrr (c) RR (d) Rr 64. Study the pedigree chart of a certain family given below and select the correct conclusion which can be drawn for the character. (a) The male parent is homozygous dominant (b) The female parent is heterozygous (c) The parents could not have had a normal daughter for this character (d) The trait under study could not be colour blindness

54 Biology-XII 65. A pea plant parent having violet coloured flowers with unknown genotype was crossed with a plant having white coloured flowers in the progeny 50% of the flowers were violet and 50% were white. The genotype constitution of the parent having violet coloured flowers was (a) Homozygous (b) Merozygous (c) Heterozygous (d) Hemizygous 66. Mendel’s principle of segregation means that the germ cells always receive (a) One pair of alleles (b) One quarter of the genes (c) One of the paired alleles (d) any pair of alleles 67. The major cause of evolution of genes and protein is (a) Point mutation (b) Chromosomal aberration (c) Sexual reproduction (d) Gene duplication and divergence 68. Which one of the following conditions correctly describes the manner of determining the sex in the given example ? (a) Homozygous sex chromosomes (XX) produces male in Drosophila (b) Homozygous sex chromosomes (ZZ) determine female sex in birds (c) XO type of sex chromosomes determine male sex in grasshopper (d) XO condition in humans as found in Turner Syndrome determine female sex 69. Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child ? (a) Only one X chromosome (b) One X and one Y chromosome (c) Two X chromosomes (d) Only one Y chromosome 70. Test cross in plant or in Drosophila involves crossing (a) the F1 hybrid with a double recessive genotype (b) between two genotypes with dominant trait (c) between two genotypes with recessive trait (d) between two F1 hybrid 71. In blood group typing in human, if an allele contributed by one parent is IA and an allele contributed by the other parent is i, the resulting blood group of the offspring will be (a) A (b) B (c) AB (d) O 72. If two pea plants having red (dominant) coloured flowers with unknown genotypes are crossed. 75% of the flowers are red and 25% are white. The genotypic constitution of the parents having red coloured flowers will be (a) Both homozygous (b) One homozygous and other heterozygous (c) Both heterozygous (d) Both hemizygous

Principles of Inheritance and Variation 55 73. A polygenic trait is controlled by 3 genes A, B and C. In a cross AaBbCc × AaBbCc the phenotypic ratio of the offspring was observed as : 1 : 6 : X : 20 : X : 6 : 1 What is the possible value of X ? (a) 3 (b) 9 (c) 15 (d) 25 74. The chromosome constitution 2n – 2 of an organism represents (a) Monosomic (b) Nullisomic (c) Haploid (d) Trisomic 75. Absence of one sex chromosome causes (b) Klinefilter’s syndrome (a) Turner’s syndrome (c) Down’s syndrome (d) Tay-sach’s syndrome. 76. Chimera is produced due to (b) Reverse mutation (a) Somatic mutation (c) Lethal mutation (d) Pleiotropic mutation 77. A normal-visioned man whose father was colour blind marries a woman whose father was also colour blind. They have their first child as a daughter. What are the chances that this child would be colour blind ? (a) 100% (b) zero percent (c) 25% (d) 50% 78. F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1 : 2 : 1. It represents a case of : (a) Co-dominance (b) Dihybrid cross (c) Monohybrid cross with complete dominance (d) Monohybrid cross with incomplete dominance 79. A test cross is carried out to : (a) determine the genotype of a plant at F2 (b) predict whether two traits are linked (c) assess the number of alleles of a gene (d) determine whether two species or varieties will breed successfully 80. Represented below is the inheritance pattern of a certain type of traits in humans. Which one of the following conditions could be an example of this pattern? Female Male mother Father Daughter Son (a) Phenylketonuria (b) Sickle cell anaemia (c) Haemophilia (d) Thalassemia

56 Biology-XII 81. Which of the following cannot be detected in a developing foetus by amniocentesis ? (a) Jaundice (b) Klinefelter syndrome (c) Sex of the foetus (d) Down syndrome 82. If two persons with ‘AB’ blood group marry and have sufficiently large number of children, these children could be classified as ‘A’ blood group, AB blood group, ‘B’ blood group in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis reveals presence of both ‘A’ and ‘B’ type of protein in ‘AB’ blood group individuals. This is an example of: (a) Complete dominance (b) Codominance (c) Incomplete dominance (d) Partial dominance 83. If both parents are carriers for thalassaemia which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child. (a) 100% (b) No chance (c) 50% (d) 25% 84. Which of the following statements is not true of two genes that show 50% recombination frequency ? (a) If the genes are present on the same chromosome, they undergo more than one crossovers in every meiosis. (b) The genes may be on different chromosomes. (c) The genes are tightly linked. (d) The genes show independent assortment. 85. Which Mendelian idea is depicted by a cross in which the F1 generation resembles both the parents ? (a) Co-dominance (b) Incomplete dominance (c) Low of dominance (d) Inheritance of one gene 86. The incorrect statement with regard to Haemophilia is (a) A single protein involved in the clotting of blood is affected (b) It is a sex linked disease (c) It is a recessive disease (d) It is a dominant disease 87. Which of the following is an x-linked recessive trait with locus in xq 28 and related with factor VIII ? (a) Haemophilia A (b) Haemophilia B (c) Christmas disease (d) Both (a) and (b) 88. Choose the false statement with reference to sickle cell anaemia: (a) Have genotype HbS/HbS (b) Have genotype HbA/HbA (c) Substitution of glutanic acid to valine (d) Have sickle shape RBC

Principles of Inheritance and Variation 57 89. A man has blood group O and his mother has A type, the genotype of mother should be. (a) IO IO (b) IA IO (c) IA IB (d) IA IA 90. Cri-du-chat belong to which of the following genetic disorder ? (a) Gene disorder (b) Autosomal disorder (c) X-chromosonal disorder (d) Allosomal disorder 91. In a population of 1000 individuals 360 belong to genotype AA, 480 to Aa and the remaining 160 to aa. Based on this data, the frequency of allele A in the population is (a) 0.6 (b) 0.7 (c) 0.4 (d) 0.5 92. A man whose father was colour blind marries a woman who had a colour blind mother and normal father. What percentage of male children of this couple will be colour blind ? (a) 50% (b) 75% (c) 25% (d) 0% 93. Fruit colour in squash is an example of (a) Complementary genes (b) Inhibitary genes (c) Recessive epistasis (d) Dominant epistasis 94. Alleles are (a) different molecular forms of a gene (b) heterozygotes (c) different phenotype (d) true breeding homozygotes 95. Which is the most common mechanism of genetic variation in the population of a sexually reproducing organism ? (a) Genetic drift (b) Recombination (c) Transduction (d) Chromosomal aberrations 96. Multiple alleles are present (a) At the same locus of the chromosome (b) On non-sister chromatids (c) On different chromosomes (d) At different loci on the same chromosome 97. Down’s syndrome is characterized by (a) 19 trisomy (b) 21 trisomy (c) only one x chromosome (d) Two x and only one y chromosome 98. During the experiments, Mendel called genes by the term (a) Traits (b) Characters (c) Factors (d) Qualities 99. If a genotype consists of different types of alleles, it is called (a) Homozygous (b) Heterozygous (c) Monoallelic (d) Uniallelic

58 Biology-XII 100. The alternative form of gene is called (b) Recessive character (a) Dominant character (c) Alternative genes (d) Allele 101. The experimental material in Mendel’s experiment was (a) Pisum sativum (b) Oryzasativa (c) Mirabilus jalapa (d) None of the above 102. In the following human pedigree, the filled symbols represent the affected individuals. Identify the type of given pedigree. (i) (ii) (iii) (iv) (a) x-linked recessive (b) Autosomal recessive (c) x-linked dominant (d) Autosomal dominant 103. A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind? (a) 1 (b) Nil (c) 0.25 (d) 0.5 Answers 1. (c) 2. (d) 3. (b) 4. (b) 5. (a) 6. (d) 7. (b) 8. (a) 9. (a) 10. (c) 11. (d) 12. (b) 13. (a) 14. (b) 15. (c) 16. (b) 17. (b) 18. (c) 19. (a) 20. (d) 21. (c) 22. (c) 23. (a) 24. (a) 25. (a) 26. (c) 27. (a) 28. (d) 29. (b) 30. (a) 31. (c) 32. (b) 33. (c) 34. (b) 35. (b) 36. (d) 37. (d) 38. (b) 39. (b) 40. (a) 41. (d) 42. (d) 43. (c) 44. (b) 45. (c) 46. (a) 47. (b) 48. (c) 49. (a) 50. (b) 51. (d) 52. (c) 53. (a) 54. (a) 55. (a) 56. (d) 57. (a) 58. (c) 59. (c) 60. (c) 61. (d) 62. (a) 63. (d) 64. (b) 65. (c) 66. (c) 67. (a) 68. (c) 69. (c) 70. (a) 71. (a) 72. (c) 73. (c) 74. (b) 75. (a) 76. (a) 77. (b) 78. (d)

Principles of Inheritance and Variation 59 79. (a) 80. (c) 81. (a) 82. (b) 83. (d) 84. (c) 85. (d) 86. (d) 87. (a) 88. (b) 89. (b) 90. (b) 91. (a) 92. (a) 93. (d) 94. (a) 95. (b) 96. (a) 97. (b) 98. (c) 99. (b) 100. (d) 101. (a) 102. (b) 103. (b) Assertion-Reason Type Questions In the following questions a statement of Assertion (A) is followed by a statement of Reason (R). — If both Assertion and Reason are true, and the Reason is the correct explanation of the Assertion, then mark (a). — If both Assertion and Reason are true, and the Reason is not the correct explanation of the Assertion, then mark (b). — If Assertion is true statement but Reason is false, then mark (c). — If both Assertion and Reason are false statements, then mark (d). 1. A. A gamete contains a single allele for each trait. R. During gametogenesis, the two alleles of each trait segregate, one passing into each gamete at random. 2. A. In 4 O’ clock/snapdragon plant a cross between a homozygous white flowered individual and a homozygous red flowered one produces pink flowered plants. R. In these plants, the flower colour is determined by three alleles. 3. A. In a person with AB blood group, the erythrocytes carry both A and B antigens on their surface. R. T he alleles IA and IB that produce AB blood group are co-dominant and both are expressed. 4. A. It is not possible for human parents heterozygous for skin colour to have children darker or lighter than themselves. R. Human skin colour is controlled by a single pair of alleles. 5. A. The person heterozygous for sickle cell trait produces both (HbA) and abnormal haemoglobin (HbS). R. The normal allele and the sickle cell allele are co-dominant. 6. A. Discontinuous variations are heritable. R. These are produced by the effects of environment.

60 Biology-XII 7. A. L aw of independent assortment holds good for the gene pairs that occur in different pairs of chromosomes. R. It is chromosomes and not the individual genes which segregate during gamete formation. 8. A. Haemophilia shows criss-cross inheritance. R. The gene that causes haemophilia is recessive and lies in the X chromosome. 9. A. In honey bee, female is diploid and male is haploid. R. Gametes are formed by meiosis in female and by mitosis in male. 10. A. Cross-over frequency (COV) is higher than the observed frequency of recombination of trait in the offspring. R. More than one cross-over may occur simultaneously between the same chromatids. Answers 1. (a) 2. (c) 3. (a) 4. (d) 5. (a) 6. (c) 7. (a) 8. (a) 9. (b) 10. (a) Matching Type Questions In the following questions match the items in Column I with the items in Column II. An item in Column I may match with more than one items in Column II. Match the Terms of Column I with Terms of Column II: I. Column I Column II (a) Pure lines (i) Sickle cell anaemia (b) Dihybrid cross (ii) Human blood groups (c) Pleiotropy (iii) True breeding (d) Heterozygous (iv) Principle of independent assortment (e) Codominance (v) Aa genotype Column II II. Column I (i) Tetrad analysis (a) Pachytene (ii) Mutagen (b) Neurospora (iii) Crossing over (c) Haemophilia (iv) Lathyrus odoratus (d) Colchicine (v) Sex linked inheritance (e) Linkage Answers I. (a)–(iii) (b)–(iv) (c)–(i) (d)–(v) (e)–(ii) II. (a)–(iii) (b)–(i) (c)–(v) (d)–(ii) (e)–(iv)

Principles of Inheritance and Variation 61 Very Short Answer Type Questions 1. What do letters P, F1 and F2 represent in heredity ? 2. Give Mendel’s monohybrid and dihybrid ratios for phenotypes. 3. On which plant did Mendel work ? 4. How many contrasting traits Mendel noted in garden pea ? 5. How many varieties of garden pea did Mendel select for his experiment ? 6. Write the genotype of man with blood group A. 7. What is the full name of father of genetics ? 8. Why is Mendel honoured as the father of genetics ? 9. What heredity principle can be derived from a cross showing 3 : 1 ratio in the F2 generation ? 10. What hereditary principle can be derived from a cross showing 9 : 3 : 3 : 1 ratio in the F2 generation ? 11. How many chromosomes are found in human cells ? 12. What is a locus ? 13. Name the phenomenon that occurs when homologous chromosomes do not separate during meiosis. 14. Name two sex linked diseases of human being. 15. Who had proposed the chromosome theory of inheritance ? 16. Why is bagging of the emusculated flowers essential during hybridization experiments. 17. Name one autosomal dominant and one autosomal recessive Mendelian disorder in humans. 18. Write the genotype of (i) an individual who is carrier of sickle cell anaemia gene but apparently unaffected, and (ii) an individual affected with the disease. 19. A human being suffering from Down’s Syndrome shows trisomy of 21st chromosome. Mention the cause of this chromosomal abnormality. 20. Name the event during cell division cycle that results in the gain or loss of chromosome. 21. Name the respective pattern of inheritance where F1 phenotype (a) does not resemble either of the two parents and is in between the two. (b) resembles only one of the two parents. 22. A garden pea plant (A) produced inflated yellow pod and another plant (B) of the same species produced constricted green pods. Identify the dominant traits.

62 Biology-XII Answers 1. Parents; First filial generation; Second filial generation. 2. 3 : 1 and 9 : 3 : 3 : 1. 3. Garden pea (Pisum sativum). 4. Seven. 5. Fourteen 6. IAIA ; IAIO. 7. Gregor Johann Mendel. 8. Because, he proposed the basic principles of heredity, which was the great contribution to genetics. 9. Principle of segregation. 10. Principle of independent assortment. 11. 46 12. Site of a gene in a chromosome. 13. Non-disjunction 14. Haemophilia and colour blindness. 15. Sutton and Boveri (1902). 16. To prevent contamination of its stigma with unwanted pollen. 17. Autosomal dominant – Myotonic dystrophy Autosomal recessive – Sickle cell anaemia. 18. (i) Carrier – HbA/HbS (ii) Affected – HbS/HbS 19. Failure of segregation of chromatids during cell division cycle resulting in the gain of a chro- mosome. 20. Failure of segregation of chromatids. 21. (a) Incomplete dominance (b) Dominance. 22. Inflated pod shape and green pod colour. Fill in the Blanks Fill in the following blanks with appropriate items: 1. Two alleles of a gene are located on the ...... chromosomes. 2. The term gene was coined by ...... . 3. Emasculation means removal of ...... . 4. A gene which controls both flower and seed coat colour in garden pea is known as ...... gene. 5. The shape of normal distribution curve for skin colour in human will be ...... .

Principles of Inheritance and Variation 63 6. An organism in which two alleles of a trait are unlike is called ...... . 7. Mendel studied inheritance of ...... pairs of contrasting trait in pea plants. 8. The two chromatids of a chromosome are held together at the ..... . 9. A chromosome is composed of a single ...... molecule. 10. Chromosome theory of inheritance was proposed by ..... and ...... . 11. In humans, males are heterogametic whereas females are ...... . 12. Non-separation of homologous chromosomes during meiosis is termed as ...... . 13. The points at which crossing over takes place are known as ........ . 14. The chromatids affected by crossing over are termed as ........ . 15. The hereditary units present in the cytoplasm are called ....... . 1. Homologous Answers 3. Anther 4. Pleiotropic 2. Johannson 6. Heterozygous (Hybrid) 7. seven. 5. Bell shape 9. double stranded DNA, 10. Sutton, Boveri, 8. centromere, 12. Non-disjunction 13. Chiasmata, 11. Homogametic, 15. Plasmagenes (cytoplasmic genes). 14. recombinants True/False Statements State whether the following statements are true or false: 1. Different genes present on the same chromosomes are always non-allelic to one another. 2. The principle of dominance is universally accepted. 3. In diploid organisms the members of each pair of genes separate during gamete formation. 4. AB blood group is an example of codominance. 5. A heterozygous individual produces only one types of gametes. 6. Skin colour is a polygenic trait which is influenced by the environmental conditions. 7. Dominance and epistasis are synonymous to each other. 8. Human blood groups are determined by multiple alleles. 9. The homologous chromosomes segregate and assort independently during meiosis. 10. The phenomenon of linkage was first noticed by Morgan in Drosophila. 11. The closely located genes on a chromosome show stronger linkage than the distant genes. 12. Genes placed adjacent in a chromosome have greater chance of crossing over. 13. Homologous chromosomes similar in both male and female are called autosomes.

64 Biology-XII 14. Colour blindness is a autosomal hereditary disease. 15. A pair of gene are linked if their recombination frequency in test cross is less than 50%. 16. One map unit corresponds to the physical distance between two genes in which one cross over occurs in every 50 meiosis. Answers 1. True 2. False 3. True 4. True 5. False 6. True 7. False 8. True 9. True 10. True 11. True 12. False 13. True 14. False 15. True 16. True Case Study Based MCQs I. A situation has been shown in the given figure. Answer the following questions : 22 + X 22 + Y 22 + XX 22 + O (a) (b) (c) (d) 1. Will there be any abnormality, when the sperm marked (a) fertilizes the egg marked (d)? (a) Yes, Turner’s syndrome (b) No, Turner’s syndrome (c) Sperm syndrome (d) None of these 2. What will be the sex of the inborn child in the above case ? (a) Male (b) Female (c) Both (a) and (b) (d) None of these 3. Mention any two external abnormalities in such a child. (a) Short stature (b) Underdeveloped breast (c) Abnormal intellegence (d) All of the above 4. What abnormality, the child will have relating to the reproductive cycle ? (a) Menstruate (b) May not menstruate (c) Both (a) and (b) (d) None of these

Principles of Inheritance and Variation 65 5. What will be the sex of the inborn child if the sperm marked (b) fertile the egg marked (c) in the above case? (a) Male (b) Female (c) Unisex (d) None of these II. Answer the following questions relating to the given figure. I II III IV V VI VII VIII IX X XI XII XIII 1. What does the given figure shows? (b) Family tree (a) Pedigree (d) None of these (c) Both (a) and (b) 2. What does the symbol indicate in the figure? (a) Male (b) Female (c) Affected female (d) None of these 3. What does the symbol indicate in the figure? (a) Effected male (b) Effected female (c) Female (d) None of these 4. What does the symbol indicate in the figure? (a) Female (b) Affected female (c) Male (d) None of these 5. If in such a figure has been used, what will it indicate? (a) Consanguineous mating (b) Mating between relatives (c) Both (a) and (b) (d) None of these Answers (a) I. 1. (a) 2. (b) 3. (d) 4. (b) 5. (c) II. 1. (c) 2. (a) 3. (c) 4. (b) 5.

Chapter-5 Molecular Basis of Inheritance Multiple Choice Questions In each of the following questions only one option is correct. Select the correct option. 1. Transcription begins when one of the following enzymes binds to a promoter site (a) DNA polymerase (b) RNA polymerase (c) Helicase (d) Gyrase. 2. Elongation of RNA polynucleotide chain always takes place (a) when RNA acts as a primer (b) 5′ → 3′ direction with new nucleotide always added at 3′ site (c) during replication of DNA (d) in any direction along the entire length of single DNA strand. 3. Aminoacyl synthetase enzyme takes part in (a) attachment of mRNA of 30S ribosome (b) transfer of activated amino acid to tRNA. (c) activation of amino acid (d) hydrolysis of ATP to AMP. 4. There are 64 codon in genetic code dictionary because (a) there are 64 types of tRNAs found in the cell. (b) there are 44 meaningless and 20 codons for amino acid. (c) there are 64 amino acids to be coded. (d) genetic code is triplet. 5. Escherichia coli fully labelled with 15N is allowed to grow in 14N medium. The two strands of DNA molecule of the first generation of bacteria have (a) Different density and do not resemble parent DNA (b) Different density but resemble parent DNA (c) Same density and resemble parent DNA (d) Same density but do not resemble parent DNA 6. Khurana first deciphered the triplet codons of (a) Serine and isolucine (b) Cysteine and valine (c) Tyrosine and Tryptophan (d) Phenylalanine and methionine

Molecular Basis of Inheritance 67 7. Experimental material in the study of DNA replication has been (a) Escherichia coli (b) Neurospora crasa (c) Pneumococcus (d) Drosophila 8. Initiation codon of protein synthesis (in eukaryotes) is (a) GUA (b) GCA (c) CCA (d) AUG 9. Nucleotide arrangement in DNA can be seen by (a) X-ray crystallography (b) Electron microscope (c) Ultra centrifuge (d) Light microscope 10. Pneumococcus experiment proved that (a) Bacteria do not reproduce asexually (b) Bacteria undergo binary fission (c) DNA is genetic material (d) RNA may sometimes control production of DNA and protein 11. The process of translation is (b) Protein synthesis (a) Ribosome synthesis (c) DNA synthesis (d) RNA synthesis 12. Because most of the amino acids are represented by more than one codon, the genetic code is (a) Overlapping (b) Wobbling (c) Degenerate (d) Generate 13. During DNA replication the two strands separate by (a) DNA polymerase (b) Topoisomerase (c) Unwindase (d) Gyrase 14. Who proved that DNA is the basic genetic material ? (a) Griffith (b) Watson (c) Baveri and Sutton (d) Harshey and Chase 15. Hydrogen bonds between cytosine and guanine are (a) 1 (b) 2 (c) 3 (d) 4 16. Protein helping in opening of DNA double helix in the form of replication fork is (a) Topoisomerase (b) DNA gyrase (c) DNA ligase (d) DNA polymerase 17. Which is not involved in protein synthesis ? (a) Transcription (b) Initiation (c) Elongation (d) Termination 18. Central dogma was proposed by (b) Temin and Baltimore (a) Beadle and Tatum (c) Klung (d) Crick

68 Biology-XII 19. DNA replication is aided by (b) DNA ligase only (a) DNA polymerase only (c) Both (a) and (b) (d) RNA polymerase 20. Teminism is the same as (b) DNA synthesis (a) Translation (c) Transcription (d) Reverse transcription 21. Which one is not true ? (b) A—C, T—C (a) A—T, G—C (c) C—G, T—A (d) G—C, A—T 22. Pyrimidine base present in RNA in place of thymine of DNA is (a) Uracil (b) Adenine (c) Cytosine (d) Guanine 23. Semi conservative DNA or chromosone replication using 15N was demonstrated by (a) Messelson (b) Taylor (c) Messelson and Stahl (d) Harshey and Chase 24. Termination of polypeptide chain formation is brought about by (a) UUG, UAG and UCG (b) UAA, UAG and UGA (c) UUG, UGC and UCA (d) UCG, GCG and ACC 25. RNA contains (b) Ribose (c) Fructose (d) Glucose (a) Hexose 26. Triplet codon refers to sequence of three bases on (d) All of these (a) mRNA (b) tRNA (c) rRNA 27. Degeneration of a genetic code is attributed to the (a) third member of a codon (b) first member of a codon (c) second member of a codon (d) entire codon 28. Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as ‘start’ or ‘stop’ codon? (a) UAC—tyrosine (b) UCG—start (c) UUU—stop (d) UGU—Leucine 29. What would happen if in a gene encoding a polypeptide of 50 amino acids, 25th codon (UAU) is mutated to UAA? (a) A polypeptide of 25 amino acids will be formed (b) A polypeptide of 24 amino acid will be formed (c) Two polypeptides of 24 and 25 amino acids will be formed (d) A polypeptide of 49 amino acids will be formed 30. In the genetic code dictionary, how many codons are used to code for all the 20 essential amino acids? (a) 60 (b) 20 (c) 64 (d) 61

Molecular Basis of Inheritance 69 31. What does “Lac” refer to in what we call lac operon ? (a) The number 1,00,000 (b) Lactose (c) Lactase (d) Lac insect 32. During transcription, the DNA site at which RNA polymerase binds is called (a) enhancer (b) promotor (c) regulator (d) receptor 33. During translation initiation in prokaryotes a GTP molecule is needed in (a) association of 50 S subunit of ribosome with initiation complex (b) formation of formyl-met-t-RNA (c) binding of 30 S subunit of ribosome with mRNA (d) association of 30 S-mRNA with formyl-met-tRNA 34. Smallest part of DNA that undergoes recombination is (a) muton (b) cistron (c) recon (d) replicon 35. What does lac refer to in lac operon? (b) Lac insect (a) Lactose (c) Lactase (d) 1,00,000 36. Jumping gene in maize was discovered by (a) Morgan (b) Khorana (c) Mc Clintock (d) Beadle and Tatum 37. The ratio consistant for a species is (b) T + C/G + A (a) A + G/C + T (c) A + C/T + C (d) G + C/A + T 38. Length of DNA with 23 base pairs is (b) 78.2 Å (a) 78.8 Å (c) 78 Å (d) 74.8 Å 39. Hola enzyme RNA polymerase attaches to DNA sequence during transcription. DNA assumes saddle like form at that point. The sequence is (a) AAAT box (b) GGTT box (c) CAAT box (d) TATA box 40. Nucleosome contains (b) Both DNA and histones (a) Only histones (c) Only DNA (d) Both DNA and RNA 41. Reverse transcriptase is also called (b) DNA dependent RNA polymerase (a) RNA dependent DNA polymerase (c) DNA dependent DNA polymerase (d) RNA dependent RNA polymerase. 42. One turn of B-DNA double helix is (b) 20 nm (a) 2 nm (c) 0.34 nm (d) 3.4 nm

70 Biology-XII 43. All the terminator codons begin with (b) Cytosine (a) Adenine (c) Uracil (d) Guanine 44. Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it ? (a) Adenine, Thymine–Purines (b) Thymine, Uracil–Pyrimidines (c) Uracil, Cytosine–Pyrimidines (d) Guanine, Adenine–Purines 45. In the DNA molecule (a) There are two strands which run antiparallel in 5´ → 3´ direction and other in 3´ → 5´. (b) The total amount of purine nucleotides and pyrimidine nucleotides is not always equal. (c) There are two strands which run parallel in the 5´ → 3´ direction. (d) The protection of adenine in relation to thymine varies with the organism 46. Thermococcus, Methanococcus and Methanobacterium examplify : (a) Bacteria that contain a cytoskeleton and ribosomes (b) Archaebacteria that contain protein homologous to eukaryotic core histones. (c) Archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively super colied. (d) Bacteria whose DNA is relaxed or positively super coiled but which have a cytoskeleton as well as mitochondria. 47. Removal of introns and joining the exons in a defined order in a transcription unit is called. (a) splicing (b) tailing (c) transformation (d) capping 48. Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a “triplet” (a) Nirenberg and Mathaei (b) Hershey and Chase (c) Morgan and Sturtevant (d) Beadle and Tatum 49. Semi conservative replication of DNA was first demonstrated in (a) Drosophila melanogaster (b) Escherichia coli (c) Streptococcus preumoniae (d) Salmonella typbimurium 50. What is not true for genetic code ? (a) A codon in mRNA is read in a non-contiguous fashion. (b) It is nearly universal. (c) It is degenerate (d) It is unambiguous. 51. Beadle and Tatum showed that each kind of mutant bread mould they studied lacked a specific enzyme. Their experiments demonstrated that

Molecular Basis of Inheritance 71 (a) Cells need specific enzymes in order to function. (b) genes are made of DNA (c) enzymes are required to repair damage (d) genes carry information for making proteins. 52. mRNA directs the building of proteins through a sequence of (a) exons (b) introns (c) codons (d) anticodons 53. The anti-parallel nature of DNA refers to (a) its charged phosphate groups. (b) the formation of hydrogen bonds between from opposite strands. (c) the opposite direction of the two strands. (d) the pairing of bases on one strand with bases on the other strand. 54. Select the two correct statements out of the four (1–4) given below about lac operon. (1) Glucose or galactose may bind with the repressor and inactivate it. (2) In the absence of lactose the repressor binds with the operator region. (3) The Z-gene codes for permease. (4) This was elucidated by Francoi’s Jacob and Jacque Monod. The correct statements are (a) (2) and (4) (b) (1) and (2) (c) (2) and (3) (d) (1) and (3) 55. The one aspect which is not a salient feature of genetic code, is its being. (a) Universal (b) Specific (c) Degenerate (d) Ambiguous. 56. Satellite DNA is useful tool in (b) Genetic-engineering (a) Forensic science (c) Organ transplantation (d) Sex determination 57. Which one of the following statements about a particular entity is true ? (a) DNA consists of a core of eight histones. (b) Centromere is found in animal cells, which produces aster during cell division. (c) The gene for producing insulin is present in every body cell. (d) Nucleosome is formed of nucleotides. 58. The 3′–5′ phosphodiester linkages inside a polynucleotide chain serve to join (a) One nitrogen base with pentose sugar (b) One DNA strand with the other DNA strand (c) One nucleoside with another nucleoside (d) One nucleotide with another nucleotide. 59. If the total amount of adenine and thymine in a double stranded DNA is 45% the amount of guanine in this DNA will be

72 Biology-XII (a) 22.5% (b) 27.5% (c) 45% (d) 55% 60. The beginning of understanding genetic transformation in bacteria was made by (a) Frederick Griffith (b) Hershey and Chase (c) Watson and Crick (d) T.H. Morgan 61. What will be the correct gene expression pathway ? (a) Gene – mRNA – Transcription – Translation – Protein (b) Transcription – Gene – Translation – mRNA – Protein (c) Gene – Transcription – mRNA – Translation – Protein (d) Gene – Translation – mRNA – Transcription – Protein 62. Which one of the following also acts as a catalyst in a bacterial cell ? (a) 23 sr RNA (b) 5 sr RNA (c) sn RNA (d) hn RNA 63. The unequivocal proof of DNA as the genetic material came from the studies on a (a) Viroid (b) Bacterial virus (c) Bacterium (d) Fungus 64. mRNA directs the building of proteins through a sequence of (a) Introns (b) Codons (c) Exons (d) Anticodon 65. Beadle and Tatum showed that each kind of mutant bread mould they studied lacked a specific enzyme. Their experiments demonstrated that (a) Cells need specific enzymes in order to function (b) Genes are made of DNA (c) Genes carry information for making proteins (d) Enzymes are required to repair damaged DNA information 66. DNA has equal number of adenine and thymine residues (A = T) and equal number of guanine and cytosine (G = C). These relationships are known as (a) Chargaff’s rule (b) Coulomb’s law (c) Le Chatelier’s principle (d) Van’t Hoff plot 67. Removal of RNA polymerase III from nucleoplasm will affect the synthesis of : (a) tRNA (b) hnRNA (c) mRNA (d) rRNA 68. PCR and Restriction Fragment Length Polymorphism are the methods for : (a) Study of enzymes (b) Genetic transformation (c) DNA sequencing (d) Genetic fingerprinting 69. Which one of the following is not a part of a transcription unit in DNA ? (a) The inducer (b) A terminator (c) A promoter (d) The structural gene