SECTION-A<\/strong><\/p>\nQuestion 1. \nWhat is the major difference you observe in the off springs produced by asexual reproduction and in the progeny produced by sexual reproduction?<\/p>\n
Question 2. \nAre the thorn of bougainvillea and tendril of Cucurbita homologus or analogous? What type of evolution has brought such similarity in them?<\/p>\n
Question 3. \nList any two economically important products for humans obtained from Apis Indica.<\/p>\n
Question 4. \nName the technique used for separating DNA fragments in the laboratory. \nQuestion 5. \nAccording to Hardy-Weinberg\u2019s principle, the allele frequency of a population remains constant. How do you interpret the change of frequency of alleles in a population?<\/p>\n
SECTION-B<\/strong><\/p>\nQuestion 6. \nThe flower of brinjal is referred to as chasmogamous while that of beans is cleistogamous. How are they different from each other?<\/p>\n
Question 7. \nA plant of Antirrhinum majus with red flowers was crossed with another plant of the same species with white flowers. The plant of the F:<\/sub> generation bore pink flowers. Explain the pattern of inheritance with the help of a cross. \nOR<\/strong> \nA woman with blood group O married a man with blood group AB. Show the possible blood groups of the progeny. List the alleles involved in this inheritance.<\/p>\nQuestion 8 \nList the specific symptoms of amoebiasis. Name the causative organism<\/p>\n
Question 9. \nDuring the secondary treatment of primary effluent, how does the significant decrease in BoD occur?<\/p>\n
Question 10. \nWhat causes speciation according to Hugo de Vries?<\/p>\n
SECTION-C<\/strong><\/p>\nQuestion 11. \nWhy are biogas plant more suitable and advantageous in rural area?<\/p>\n
Question 12. \nIndian government had taken several measures to control the vehicular air pollution in Delhi and other cities of India. Enlist any three of them.<\/p>\n
Question 13. \nAmoebiasis is often caused by an intestinal parasite which is found in the large intestine of human beings. Give the name of the organism responsible for this. Also write the symptoms and mode of transmission responsible for the disease.<\/p>\n
Question 14. \nEnlist the main differences between the two types of nucleic acids found in living systems. \nOR \n<\/strong>Study the figure given below and answer the following questions \n \n(1) Identify the molecule \u2018X\u2019 synthesized by V gene. How does this molecule get inactivated? \n(2) Identity the structural genes that codes for 3-galactosidase. \n(3) When does the transcription of this gene gets stopped?<\/p>\nQuestion 15. \nExpand the term GMO. Also explain the fact in what form a GMO differs from a hybrid?<\/p>\n
Question 16. \nBy taking an example of some of Australian marsupials and Australian placental mammals, briefly explain the phenomenon of adaptive radiation and convergent evolution in different species. \nQuestion 17. \nIt is extremely important to test a new plant variety in a systematic way during different plant breeding programmes in a geographically vast country like India. Justify.<\/p>\n
Question 18. \n(1) List any two conditions on which the development of a diploid cell depends. \n(2) If the number of chromosomes present in the meiocyte of a plant is 24, then work out the number of chromosomes in the gamete, zygote and embryo of this plant.<\/p>\n
Question 19. \nOn a visit to a food processing industry, students saw that workers were working in a huge tank size vessels. Teacher explained them that these vessels are used for the process of fermentation.<\/p>\n
\nWrite about the process of fermentation and how it takes place?<\/li>\n List some important applications of microbes in different industries.<\/li>\n<\/ol>\nQuestion 20. \nBiotechnologists identified the source and isolated different types of cry genes from the bacterium Bacillus thuringiensis and incorporated that into many crops. Briefly explain how have these genes brought beneficial changes in the genetically modified crops and to mankind?<\/p>\n
Question 21. \nThe diagrammatic illustration of connection between the different trophic\u00a0levels is given below: \n \n(1) Identify the type of ecological pyramid given below and explain what do the base and the apex of this pyramid indicate? \n(2) Give examples of such types of ecological pyramids with respect to\u00a0number and biomass.<\/p>\n
Question 22 \nBranching descent and natural selection acts as two main concepts of Darwinian theory of evolution. Discuss each concept with the help of a suitable example<\/p>\n
SECTION-D<\/strong><\/p>\nQuestion 23. \nNeeta, a Class Xth<\/sup> student was selected by her teacher for the debate competition to represent her school. She went home happily and told her mother about the same. Her mother denied her permission to participate as the topic for the debate was on AIDS\/HIV. Neeta had a very clean argument with her mother upon this. What according to you Neeta must have said to her mother to impress her to allow her to participate in the competition?<\/p>\nSECTION-E<\/strong><\/p>\nQuestion 24. \nGiven below is the type of global biodiversity representing the proportionate number of species of major taxa of plants. \n \nObserve the diversity carefully and answer the questions that follow: \n<\/strong>(1) Identify the most endangered group of plants among all the categories. \n(2) What may be the reason behind such a less population of mosses and ferns? \n(3) Name the most advanced and the most primitive group of plants in a biodiversity given above. \n(4) Fungi, inspite of being heterotroph are able to sustain themselves as a large population. Explain. \nOR \n<\/strong>With the help of a flowchart explain what are the various major approaches to conserve biodiversity?<\/p>\nQuestion 25. \nThe graph given below is representing the reproductive cycle in females. Analyse the graph in regard of a normal menstrual cycle and answer the questions given below. \n \n(1) Identify the hormones marked as \u2018X\u2019 and \u2018Y\u2019 \n(2) Explain the ovarian phases during menstrual cycle.<\/p>\n
(a) 5th day to 12th day of the cycle. \n(b) 14th day of the cycle. \n(c) 16th day to 25th day of the cycle.<\/p>\n
(3) What influence does hormones \u2018X\u2019 \nOR \n<\/strong>Male and female gametes in human beings differ from each other in both structure and function. Enumerate some major differences between the two.<\/p>\nQuestion 26. \nA single mutant allele is responsible for the abnormal formation of haemoglobin (i.e. Hbs<\/sup>). If it is present in a homozygous state (Hbs<\/sup>Hbs<\/sup>), son develops a sickle cell anemia while shows few symptoms if it is found in a heterozygous state (HbA<\/sup>Hbs<\/sup>). On the basis of the above situation, work out a cross supposing a condition in which a woman\u2019s mother homozygous for allele marries a male who is heterozygous for the allele. Indicate the probability of having a normal or a diseased child for each of her pregnancy. \nOR \n<\/strong>Haemophilia and colour blindness are sex-linked recessive disorders being determined by the alteration or mutation in the single gene. Mention the pattern of inheritance of both disorders in human beings with a help of a cross.<\/p>\nAnswers<\/strong><\/p>\nSECTION-A<\/strong><\/p>\nAnswer 1. \nOffsprings produced through asexual reproduction are genetically identical to each other as well as to their parents, while sexually produced offsprings show genetic variations leading to evolution.<\/p>\n
Answer 2. \nHomologous organ. Divergent evolution has brought such a similarity in them.<\/p>\n
Answer 3. \nHoney and Beeswax.<\/p>\n
Answer 4. \nGel electrophoresis.<\/p>\n
Answer 5. \nChange of frequency of allele in a population will result in natural selection leading to the evolution.<\/p>\n
SECTION-B<\/strong><\/p>\nAnswer 6. \nBrinjal has chasmogamous flowers, as they are open with exposed stamen and stigma. Such flowers show cross pollination as well as self-pollination. On the other\u00a0cleistogamous flowers, as they never open, even at maturity, show self-pollination.<\/p>\n
Answer 7. \nInheritance of flower colour in Antirrhinum majus. \n \nThe above pattern shows law of independent assortment which states that when two pairs of traits are combined in a hybrid, segregation of one pair of characters is independent of the other pairs of characters \n <\/p>\n
Answer 8. \nSymptoms of amoebiasis are:<\/strong> \n(a) Abdominal pain \n(b) Stools with excess mucus \n(c) Constipation \nCausative organism is Entamoeba histolytica.<\/p>\nAnswer 9. \nDuring secondary treatment of primary effluents, vigorous growth of useful aerobic microbes into floes occur when it is agitated mechanically and air is pumped into it in a large aeration tank. These microbes, while growing, consume major part of organic matter in the effluent which reduces BoD.<\/p>\n
Answer 10. \nAccording to Hugo de Vries speciation is caused due to sudden mutations in existing population which are directionless and random.<\/p>\n
SECTION-C<\/strong><\/p>\nAnswer 11. \nBiogas plants are most suitable and advantageous in rural areas because of the following reasons:<\/strong><\/p>\n\nRaw material for biogas plant is mainly cow dung which is available in plenty in rural areas where cattle are used.<\/li>\n Biogas is used for lighting and cooking in these areas as distribution is only in short distances.<\/li>\n The spent slurry from the biogas plant is used as a fertiliser for, agriculture, hence are more suitable in rural areas.<\/li>\n<\/ol>\nAnswer 12. \nThree measures to control the vehicular air pollution are<\/p>\n
\nReducing the use of fossil fuels.<\/li>\n Use of catalytic converters, electrostatic precipitators and other control devices.<\/li>\n Plantation of more trees especially the ones which accumulate pollutants and filters the air.<\/li>\n<\/ol>\nAnswer 13. \nAmoebiasis is caused by Entamoeba histolytica. \nSymptoms.<\/strong> \n(1) The patient passes out blood and mucus with stools. \n(2) He also experiences griping pain in the abdomen with a fever. \nMode of transmission is usually through faecal and oral route, by sexual transmission or by vectors such as flies, cockroaches, etc.<\/p>\nAnswer 14. \nDifferences between DNA and RNA<\/p>\n
\n\n\nDNA<\/strong><\/td>\nRNA<\/strong><\/td>\n<\/tr>\n\nIt is the known genetic material found in all the organisms.<\/td>\n It is the known genetic material found only in some viruses.<\/td>\n<\/tr>\n \nTt is mainly double-stranded with the exception of some viruses, \n(e.g. \u03c6 x 174)<\/td>\n It is mainly single-stranded with the exception of some viruses (e.g. double stranded in Retrovirus)<\/td>\n<\/tr>\n \nThe sugar found is deoxyribose.<\/td>\n The sugar found is ribose.<\/td>\n<\/tr>\n \nNitrogenous bases present are adenine, guanine, thymine and cytosine.<\/td>\n Nitrogenous bases present are adenine, guanine, thymine and uracil.<\/td>\n<\/tr>\n \nIt is chemically less reactive and structurally more stable.<\/td>\n It is chemically more reactive and structurally less stable.<\/td>\n<\/tr>\n \nIt has the ability to replicate itself.<\/td>\n It is formed by DNA.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n(1) Molecule \u2018X\u2019 synthesized by \u2018i\u2019 gene is a repressor protein. It gets inactivated on combining with an inducer molecule. \n(2) Z gene. \n(3) Transcription of gene stops in the following conditions:<\/strong><\/p>\n\nWhen substrate lactose is not available.<\/li>\n And when energy source i.e. glucose is available to the cells.<\/li>\n<\/ul>\nAnswer 15. \nGMO stands for Genetically Modified Organism. \nIn order to produce a hybrid we need a cross between genome of two species of strain. While, in case of GMOs, foreign genes are introduced in an organism and is usually maintained as an extra-chromosomal entity or gets integrated into the genome of an organism.<\/p>\n
Answer 16. \nAdaptive radiation is known as the process of evolution of different species in a given geographical area starting from a point and literally radiating to the other areas of the habitat. For example, many Australian marsupials, different from each other, such as kangaroo, sugar glider, etc had evolved from a common ancestral stock, but all within the Australian continent. Thus, when more than one adaptive radiation occur in an isolated geographical area, Convergent evolution is said to occur.<\/p>\n
Likewise Australian placental mammals also shows adaptive radiation in evolving into varieties of such placental mammals. Each one of these appear similar to the corresponding marsupial, e.g. placental wolf and Tasmanian wolf, anteater and numbat, etc.<\/p>\n
Answer 17. \nBefore the generation of new plants through the plant breeding programmes, they need to be evaluated for their yield and other agronomic traits of quality, disease resistance etc. \nThis testing is done on the farmer\u2019s field itself for atleast three growing seasons, at different locations in the country representing all the agroclimatic zones, where the crop is usually grown. The material is then evaluated in comparison to the best available local crop cultivar known as a check or a reference cultivar.<\/p>\n
Answer 18. \n(1) Zygote, a diploid cell is formed as a result of fusion of male and female gametes. \nIts development depends on the following two main conditions: \n(a) A type of life cycle of the organism \n(b) Environment to which it is exposed to<\/p>\n
(2) If the number of chromosomes present in meiocyte (2n) is 24, \nThen, the number of chromosomes in gamete will be (n) = 12. \nNumber of chromosomes in zygote (2a?) will be = 24 \nAnd the number of chromosomes in an embryo (2n) will be = 24<\/p>\n
Answer 19. \n(1) Fermentation is known as the process of conversion of carbohydrates to alcohol and CO2 <\/sub>with the help of microbes such as bacteria and yeast. Microbes via fermentation are utilised for the synthesis of number of products that are valuable for human beings. \n(2) Some of the important applications of microbes are<\/p>\n\nIn the production of bread using baker\u2019s yeast.<\/li>\n To ferment fish, soyabean, bamboo shoots, etc.<\/li>\n To produce different varieties of cheese by fermentation.<\/li>\n To produce wine, beer and other alcoholic drinks by fermentation.<\/li>\n In the production of vinegar.<\/li>\n<\/ul>\nAnswer 20. \nBt toxin genes were isolated from the bacterium Bacillus thuringiensis and was incorporated into several crops like cotton, tomato etc. \nThe choice of the genes depends on the crop and the targeted pest, as most Bt toxins are insect group specific. This toxin is coded by a gene named \u2018cry\u2019, e.g. Gene cry IAc and cry IIAb control cotton bollworms and that of cry IAb controls com borer.<\/p>\n
Answer 21. \n(1) The given pyramid is a spindle shaped ecological pyramid. The base and the apex of this pyramid is representing the producer (1st trophic level) and tertiary level consumer respectively. \n(2) Examples of such ecological pyramid are: \n<\/strong>(a) Pyramid of number in a tree ecosystem, \n(b) Pyramid of biomass in a lake.<\/p>\nAnswer 22. \nBranching descent is the ability of different species adapted to different habitat which come from common ancestors, e.g. Darwin\u2019s finches varieties arise from grain eaters. Australian marsupials evolved from common marsupials. \nNatural selection is a process in which heritable variations help in the survival of an organism and enable them to reproduce and produce large number of off springs. There may be change in the frequency of genes and alleles in the future generations. It leads to the formation of a new species, e.g. evolution of marsupials of Australia from common ancestor.<\/p>\n
SECTION-D<\/strong><\/p>\nAnswer 23. \nNeeta told her mother that in spite of living in such an educated society, the awareness among our people has not yet reached to that extent which is actually needed. Thus, the forceful and constant reminding is eventually required. She also explained her mother that due to this unawareness, our country is becoming over-populated and number of AIDS related cases are increasing constantly. \nApart from the unprotected sexual contacts, AIDS can also spread due to following other reasons as:<\/p>\n
\nUse of contaminated razors or other instruments used for piercing different body parts, e.g. pinna.<\/li>\n Transfusion of infected blood or blood products.<\/li>\n Organ transplant<\/li>\n Parturition, etc. \nHence, it is not shameful to discuss about AIDS\/HIV and ways to control it.<\/li>\n<\/ol>\nSECTION-E<\/strong><\/p>\nAnswer 24. \n1. Mosses are the most endangered group of plants. \n2. Population of mosses and ferns is less due to the following reasons:<\/strong><\/p>\n\nEnvironment pollution<\/li>\n Increase in urbanization<\/li>\n Habitat destruction<\/li>\n Expansion in agriculture<\/li>\n<\/ul>\n3. Angiosperm and algae respectively are the most advanced and primitive group of plants in a given biodiversity. \n4. Fungi are heterotrophic in nature due to the lack of chlorophyll. They are able to sustain themselves as a large population because of their ability of reproducing both asexually and sexually. \nOR \n \n<\/strong>Tn-Situ \nIn-Situ conservation involves the protection of species in their natural habitat:<\/strong><\/p>\n\nBiodiversity hotspots are the region of high levels of species richness and high degree of endemism (that is species confined to that region and not found anywhere else). The total number of biodiversity hotspots are 34. Three hotspots, which cover India are Western Ghats\/ Sri Lanka, Indo-Burma and Eastern Himalaya.<\/li>\n Protected areas are ecologically rich and biodiversity rich regions. India has 14 Biosphere Reserves, 90 National Parks and 449 Wildlife Sanctuaries. The first National Park set up in Tndia was Jim Corbett National Park.<\/li>\n<\/ol>\nEx-Situ<\/strong><\/p>\n\nProtection of gametes can be done by storing material in the places where stocks remain viable for a longer period of time without harming their genetic variability.<\/li>\n Protection of threatened species comes under the category of off-site collections of various wild and domesticated species. India has around 2,75,200 parks where animals which have become extinct in wild are maintained and has around 35 botanical gardens to collect, cultivate and display various different varieties of plant species.<\/li>\n<\/ol>\nAnswer 25. \n(1)Hormone \u2018X\u2019 is Luteinising Hormone (LH). \nHormone \u2018Y\u2019 is Follicle Stimulating Hormone (FSH).<\/p>\n
(2) (a) Follicular phase (proliferative phase) \n(b) Ovulatory phase (release of ovum). \n(c) Luteal phase<\/p>\n
(3) (a) FSH is secreted by the anterior pituitary, which stimulates the ovarian follicle to secrete oestrogen, which in turn stimulates the proliferation of the endometrium of the uterine wall. \n(b) Both LH and FSH attain a peak level in the middle of cycle (about 14h day). Rapid secretion of LH leading to its maximum level during the mid-cycle is called LH surge which induces the rupture of Graafian follicle’and thereby the release of an ovum (ovulation). \n(c) The remaining cells of ovarian follicles are further stimulated by the LH to develop corpus luteum which secretes large amount of progesterone, a hormone essential for the maintenance of an endometrium. \nOR \n<\/strong><\/p>\n\n\n\nMale Gamete (Sperm)<\/strong><\/td>\nFemale Gamete (Ovum)<\/strong><\/td>\n<\/tr>\n\nMale gamete (Sperms) are produced inside the testes.<\/td>\n Female gamete (ova) are developed inside the ovaries.<\/td>\n<\/tr>\n \nThe maturation of sperms requires about 64 days.<\/td>\n The maturation of ova requires several years.<\/td>\n<\/tr>\n \nMillions of sperms are produced per day.<\/td>\n Only one ovum matures every 28 days.<\/td>\n<\/tr>\n \nSperms are motile in nature.<\/td>\n Ovum is non-motile in nature.<\/td>\n<\/tr>\n \nReserve food material is less<\/td>\n Reserve food material is sufficient.<\/td>\n<\/tr>\n \nA sperm is differentiated into four parts, i.e. head, neck, middle piece and tail.<\/td>\n Ovum is not differentiated into different parts.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nAnswer 26. \n \n50% Homozygous for the Hbs<\/sup> allele. \n50% Heterozygous for both Hbs<\/sup> and HbA<\/sup> allele. \nAbove cross shows that a child has the equal probability of developing into a normal child or with some symptoms of the disease. This therefore, proves that a woman has no risk of giving birth to a child everytime she conceives. \nOR \n<\/strong>Haemophilia is a blood disorder which in majority cases transmitted from an unaffected carrier female to some of the male offsprings. The gene for haemophilia is located on the X-chromsome. The possibility of female becoming haemophilic is extremely rare: \n <\/p>\nThis indicates that for a female to become haemophijlic in a homozygous condition, mother of such female should be carrier and a father should be haemophillic. \nColour blindness, on the other hand, is the inability to distinugish among some or all colours. In this disorder, mutant forms of genes changes the light absorbing capacity of sensory receptors inside the eyes. This trait is mainly common in men, but heterozygous women may also shows symptoms and passes on the disorder to some of her sons.<\/p>\n
Colour blindness, like any other disorder may also shows a criss-cross inheritance, i.e., it transmits from father to his daughter and from mother to her son. \n <\/p>\n
We hope the CBSE Sample Papers for Class 12 Biology Paper 4 help you. If you have any query regarding CBSE Sample Papers for Class 12 Biology Paper 4, drop a comment below and we will get back to you at the earliest.<\/p>\n","protected":false},"excerpt":{"rendered":"
These Sample papers are part of CBSE Sample Papers for Class 12 Biology. Here we have given CBSE Sample Papers for Class 12 Biology Paper 4. CBSE Sample Papers for Class 12\u00a0 Biology Paper 4 Board CBSE Class XII Subject Biology Sample Paper Set Paper 4 Category CBSE Sample Papers Students who are going to … Read more<\/a><\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[6805],"tags":[],"yoast_head":"\nCBSE Sample Papers for Class 12 Biology Paper 4 - CBSE Library<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n