Students who are going to appear for CBSE Class 12 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 6 of Solved CBSE Sample Paper for Class 12 Biology is given below with free PDF download solutions.<\/p>\n
Time: 3 Hours<\/strong> General Instructions:<\/strong><\/p>\n SECTION-A<\/strong><\/p>\n Question 1. Question 2. Question 3. Question 4. Question 5. SECTION-B<\/strong><\/p>\n Question 6. Question 7. Question 8. Question 9. Question 10. SECTION-C<\/strong><\/p>\n Question 11. Question 12. Question 13. Question 14. Question 15. Question 16. Question 17. Question 18. Question 19. Question 20. Question 21. Question 22. SECTION-D<\/strong><\/p>\n Question 23. SECTION-E<\/strong><\/p>\n Question 24. Question 25. Question 26. Answers<\/strong><\/p>\n SECTION-A<\/strong><\/p>\n Answer 1. Answer 2. Answer 3. Answer 4. Answer 5. SECTION-B<\/strong><\/p>\n Answer 6. Answer 7. Answer 8. Answer 9. Answer 10. SECTION-C<\/strong><\/p>\n Answer 11. Answer 12. Answer 13. Answer 14.<\/p>\n Answer 15.<\/p>\n Answer 16. Primary Succesion starts on the bare rock with invasion of pioneer species<\/p>\n \u2193<\/p>\n Lichens by secreting acids help in weathering and soil formation<\/p>\n \u2193<\/p>\n Bryophytes, small plants emerged out which are able to take hold in small amount of soil<\/p>\n \u2193<\/p>\n These arc succeeded by bigger plants\/trecs in different stages as reed-swamps, submerged plants, March meadow, scrub & forest, respectively<\/p>\n \u2193<\/p>\n Climax forest community is achieved which remains stable till environment remain same.<\/p>\n \u2193<\/p>\n Xerophytic habitat gets converted to mesophytic one over a span of time<\/p>\n Answer 17. Answer 18. (2) DNA ligase:<\/strong> It helps in joining the discon- tinously synthesised fragments of strand with polarity (3) DNAhelicas:<\/strong> It facilitates unwinding of DNA strands for replication.<\/p>\n Answer 19. Answer 20. (2) CSI (Intra Cytoplasmic Sperm Injection):<\/strong> First a sperm is carefully injected directly into the center of the ovum placed in a nutrient medium in the laboratory using micro needle. The early embryo so formed is transferred into the Fallopian tube of the female for further development.<\/p>\n (3) AIT (Artificial Insemination Techniq<\/strong>ue): It is commonly used in cases where male partners are unable to inseminate the female due to very low sperm counts in the ejaculation. This technique, first collects the semen either from the husband or a healthy donor and is artificially introduced into the vagina or the uterus of the female.<\/p>\n Answer 21. Answer 22. SECTION-D<\/strong><\/p>\n Answer 23. \u00a0SECTION-E\u00a0<\/strong><\/p>\n Answer 24. At first the transformed cells are plated on the antibiotic plate which has not been insertionally inactivated (say ampicillin) and kept for overnight for growth of transformants. These transformants are then replica-plated on second antibiotic (say, tetracycline) plate (which got inactivated due to insertion of gene) for selection of recombinants. The recombinants will grow only on ampicillin plate.<\/p>\n This whole process is laborious and time consuming as it needs two overnight incubation. On contrary, if insertional inactivation of a marker that produces colour in the presence of a chromogenic compound is chosen, then the recombinants and non-recombinants on a single medium plate can be distinguished only after overnight growth (containing one antibiotic and the chromogenic compound). Answer 25. OR<\/strong><\/p>\n Importance of biogas Answer 26. (b) Selectable marker:<\/strong> It selectively permits only the growth of the transformants by identifying or selecting the transformants and eliminating non-transformants.<\/p>\n (c) Cloning sites:<\/strong> These are the sites which a vector requires to link a foreign or alien DNA for commonly used restriction enzyme, e.g., restriction sites in E. Coli cloning vector includes Hindi II, Ecor I, BamW II, Sal I, Prul etc.<\/p>\n (2) 1. Cutting of desired gene at specific location can be carried out by incubating purified DNA molecule with the restriction enzyme at some optimal condition. The progress of restriction enzyme digestion can be checked by Agarose gel electrophoresis.<\/p>\n 2. Synthesis of multiple copies of the desired gene is also known as replication of DNA in vitro and can be achieved by PCR (Polymerase Chain Reaction). This involves three three main steps.<\/p>\n We hope the CBSE Sample Papers for Class 12 Biology Paper 6 help you. If you have any query regarding CBSE Sample Papers for Class 12 Biology Paper 6, 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 6. CBSE Sample Papers for Class 12\u00a0 Biology Paper 6 Board CBSE Class XII Subject Biology Sample Paper Set Paper 6 Category CBSE Sample Papers Students who are going to […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[6805],"tags":[],"yoast_head":"\n
\nMaximum Marks: 100
\n<\/strong><\/p>\n\n
\nIt is said that process of oogenesis terminates when the oocyte changes into a Graafian follicle. Why?<\/p>\n
\nGive examples of each of autosomal dominant and autosomal recessive Mendelian disorder found in human beings.<\/p>\n
\nAlgal blooms affect the life in water bodies. Explain how.<\/p>\n
\nState the type of barrier of immune system with which a person is born and is always available to protect the body.<\/p>\n
\nKangaroo rat does not drink water but is still able to fulfill its water needs. Justify.<\/p>\n
\nA farmer was conscious about the growth of his crops and their nutrient quality. What way would you suggest to him to have better growth of crops without harming its quality?<\/p>\n
\nPistil has the ability to recognise the pollen grain of the right type.How?
\nOR
\n<\/strong>Mention two important characteristics in the sexual reproduction of frogs and bony fishes.<\/p>\n
\nPranay and his group performed tissue culture experiment using explants in vitro. The plants thus, obtained as a result were all genetically identical to the parent plant. State the procedure of how they are cultured? Also tell what are these plants known to be?<\/p>\n
\nA comparative anatomy and morphological evidence shows the similarities and differences among the organisms of today and those existed years ago. Explain the two ways in which these can be determined.<\/p>\n
\nList any two ways to show that genetic modification in plants has been done to change their phenotypic expression.<\/p>\n
\nState the reason behind using 35<\/sup>S and 32<\/sup>P in the experiments conducted by Hershey and Chase to establish that DNA acts as a genetic material.<\/p>\n
\n![\"CBSE](\"https:\/\/www.aplustopper.com\/wp-content\/uploads\/2018\/12\/CBSE-Sample-Papers-for-Class-12-Biology-Paper-6.1.png\")
\nThe biogas plant shown below is used in rural areas for the production of biogas.
\n(1) Observe the figure and label the different parts marked.
\n(2) Explain the working of a biogas plant.
\nOR
\n<\/strong>In what way are baculoviruses used as the biological control agents? Mention their importance in organic farming.<\/p>\n
\nExplain the structure of a typical micro\u00adsporangium with a help of its labelled enlarged view. Also highlight the major roles played by the innermost layer of the microsporangium.<\/p>\n
\nGive reasons for the following:
\n<\/strong>(1) Parasites tend to lose certain organs.
\n(2) Clownfish lives among the tentacles of sea anemone.
\n(3) Desert plants bears thick cuticle on their leaf surfaces.<\/p>\n
\n(1) State the type of technique shown in the diagram and its importance.
\n![\"CBSE](\"https:\/\/www.aplustopper.com\/wp-content\/uploads\/2018\/12\/CBSE-Sample-Papers-for-Class-12-Biology-Paper-6.2.png\")
\n(2) Identify the step occurring in the middle and its utility.
\n(3) Mention the role of taq polymerase in the technique<\/p>\n
\nDraw an outline sketch of xerarch succession occurring in an ecosystem.<\/p>\n
\nThere is more species rich biodiversity in the tropical latitude when compared to the temperate ones. Justify the statement giving two reasons.<\/p>\n
\nDiagramatically represent the schematic sketch of replication fork of DNA indicating the importance of different enzymes involved in it.<\/p>\n
\nAkshay\u2019s father often complains about a regular chest pain, persistent cough, hoarseness and feeling of breathlessness. The doctor predicted that his father might be suffering from any form of a cancer and should be diagnosed as early as possible. Mention the types of method to diagnose cancer.<\/p>\n
\nDifferent kinds of assisted reproductive technology has now provided the hope for many infertile couples to achieve pregnancy by artificial means. Explain any three of them.<\/p>\n
\nOn the basis of Darwin\u2019s theory of natural selection explain the appearance of new forms of life on earth. Justify the statement.<\/p>\n
\nBiodiversity is important to mankind in both cultural and religious way. Justify the statement.<\/p>\n
\nRicha\u2019s father and his family members were curious to have a male child after Richa, in their family. He used to always blame her mother for giving birth to a girl child and was forcing her to undergo a test for the identification of the sex of the child. Richa\u2019s mother always refused to do this. How do you think Richa as a bright student of biology will convince her father and her family about the criteria of sex determination in human beings. Justify the arguments of Richa and her family by mentioning the positive aspects towards the situation.<\/p>\n
\nFor selection of recombinants, insertional inactivation of antibiotic marker has been superceeded by insertional inactivation of a merger gene coding for chrogenic substrate. Give reasons.
\nOR
\n<\/strong>(1) Draw a diagrammatic sectional view of human ovary showing different stages of oogenesis along with a corpus luteum.
\n(2) Where does morula form in human female? Also explain the process of its development from zygote.<\/p>\n
\nAmit had a business of supplying the milk of cattle to different homes. He was disturbed with his financial condition and was not in a condition to buy new cattle. One of his friends advised him that he can easily increase his herd size of the desired variety by the use of MOET programme. List the different steps involved in conducting the respective programme mentioning the utility of the programme.
\nOR
\n<\/strong>(1) Mention the process of the production of activated sludge during sewage treatment.
\n(2) Explain the process of production of biogas with this activated sludge with the importance of the biogas so produced in a daily life.<\/p>\n
\n(1) Describe the important characteristics a cloning vector must possess.
\n(2) State the reason behind a fact that a DNA cannot pass through the cell membrane.
\nOR
\n<\/strong>If a desired gene is identified in an organism for some experiments, explain the process of the following:
\n(1) Cutting the desired gene at specific location.
\n(2) Synthesis of multiple copies of this desired gene mentioning all steps required.<\/p>\n
\nThe process of oogenesis in human females begins with the formation of primary oocytes at puberty and terminates at the time of menopause.<\/p>\n
\n(1) Autosomal dominant – Myotonic dystrophy
\n(2) Autosomal recessive – Sickle-cell anaemia<\/p>\n
\nAlgal blooms pollutes water and deteriorates its quality by depleting the oxygen content due to which the water becomes toxic.<\/p>\n
\nThe type of barriers of innate immune system are
\n(1) Physical barrier
\n(2) Physiological barrier
\n(3) Cellular barrier
\n(4) Cytokine barrier<\/p>\n
\nKangaroo rat is able to fulfill its water needs by the oxidation of internal stored fat where water is formed as a by product.<\/p>\n
\nFarmer should apply a biofertiliser to his crops as it contains micro organisms which when applied to the plants or soil promotes the growth of the crops without harming the nutrient quality of the plant.<\/p>\n
\nMediation of continuous dialogue between pollen grains and the pistil by the chemical components of the pollen and pistil interaction helps in recognition of right or wrong pollen grain. If the pollen is of wrong type, the pistil rejects the pollen by preventing pollen germination on stigma or pollen tube growth in the style.
\nOR
\n<\/strong>Sexual reproduction of frogs and bony fishes has two main characteristics
\n(1) Both of these release mature gametes simultaneously.
\n(2) Both of them enhance the chances of syngamy (external fertilisation) by releasing a large number of gametes in water.<\/p>\n
\nThe explant is grown in a petridish\/test-tube under sterile conditions in a special nutrient medium which must contain sucrose, inorganic salts, vitamins, minerals, amino acids, growth regulators like auxin and cytokinins, etc. The medium of the culture is replaced regularly to restore nutrients in it. As all the plants (produced by tisse culture) are genetically identical to the original plant from where they are cultured, hence they are called somaclones.<\/p>\n
\nTwo ways in which these differences and similarities can be determined are either analogy or homology.<\/p>\n\n
\nGenetic modification of plants has been done to change the following phenotypic expression of the plants by the following two ways:<\/p>\n\n
\nHershey and Chase worked with viruses that infects bacteria, i.e. bacteriophages to prove that DNA is the genetic material. To prove this they grew some bacteriophages on a medium containing radioactive 32<\/sup>P, while another set of viruses were grown on 35<\/sup>S medium.Viruses grown in medium containing 32<\/sup>P contained radioactive DNA but not the radioactive protein, because only DNA contains phosphorus and proteins. While, on the other hand, vimses grown in radioactive 35<\/sup>S contained radioactive protein but not radioactive DNA because DNA does not contain sulphur. Both the radioactive virus types were allowed to infect E. Coli separately. Infected bacteria were found radioactive, indicating that DNA was the material that passed from virus to bacteria.<\/p>\n
\n(1) Different parts marked are A – Sludge tank, B – Gas holder, C – Charge Pit
\n(2) Biogas plant consists of a concrete tank (10-15 feet deep) in which the biowastes are collected and slurry of dung is fed. A floating cover is placed over the slurry which is allowed to rise as the gas is produced in the tank due to the microbial activity of methanogens. Methanogens grows anaerobically on cellulose present in cow dung producing large amount of methane (CH4<\/sub>), hydrogen (H2<\/sub>) and carbon dioxide (CO2<\/sub>). The biogas plant has an outlet being connected to a pipe to supply biogas. The spent slurry is removed through another outlet and is used as a manure.
\nOR
\n<\/strong>Baculoviruses are known as the pathogens that attack insects and other arthropods. These are used as a biological control and are excellent candidates for species-specific insecticidal applications. They do not show negative impact on plants, birds and non-target insects. Therefore, they are used as biological control agents.
\nIn organic farming it is beneficial for conserving desirable insects to aid in an overall integrated Pest Management (PM) programme. They are also used when an ecologically sensitive area is being treated to kill harmful insects and conserve the beneficial ones<\/p>\n
\n![\"CBSE](\"https:\/\/www.aplustopper.com\/wp-content\/uploads\/2018\/12\/CBSE-Sample-Papers-for-Class-12-Biology-Paper-6.3.png\")
\nMicrosporangium or pollen sac is a sporangium that produces numerous spores, which further give rise to a male gametophyte. Each microspore germinates to a pollen grain. Microsporangium is made up of four different layers, i.e. epidermis, also known as common anther covering, endothecium, 1 -3 middle layers and an innermost layer called tapetum.
\nMajor role played by the tapetum are<\/strong>:<\/p>\n\n
\n
\n
\nRecombinant DNA Technology (RDT) and in various other fields to amplify a small amount of DNA.<\/li>\n
\nXerarch succession takes place in dry areas and the series progresses from xeric to mcsic conditions. Finally, the climax community remains stable as long as the environment remains unchanged.
\nThe stage of xerarch succession undergoes in a following way:<\/strong><\/p>\n
\nThe reasons behind the fact is that:<\/strong>
\n(1) As tropical environments are less seasonal, more constant and predictable they promote niche specialisation at constant environment and leads to a greater species biodiversity.
\n(2) Tropics has good availability of solar energy contributing to the higher productivity which finally in turn contributes to the greater diversity.<\/p>\n
\n![\"CBSE](\"https:\/\/www.aplustopper.com\/wp-content\/uploads\/2018\/12\/CBSE-Sample-Papers-for-Class-12-Biology-Paper-6.4.png\")
\nImportance of different enzymes required in DNA replication are:
\n(1)<\/strong> DNA polymerase:<\/strong> It is a main enzyme which is highly efficient to catalyse the polymerisation of deoxyribonucleotides in a short span of time.<\/p>\n
\n5′ \u2192 3′ after polymerisation.<\/p>\n
\nMain methods to detect cancer are:<\/strong><\/p>\n\n
\n(1)<\/strong> GIFT (Gamete Intra Fallopian Transfer):<\/strong> helps in treatment of infertility cases where an ovum from the donor female is introduced into the Fallopian tube of the female who cannot produce ova but can provide suitable environment for fertilisation. Such women accept sperms from her husband during copulation.<\/p>\n
\nAccording to Darwin\u2019s theory of natural selection the organism which are well adapted to their environment are fit to survive in the struggle for existence. The key factor in determining survival is adaptation to the environment, be it physical, physiological or the behavioural, gives ait individual a survival advantage over another, will act as a selective advantage in the struggle for existence.This natural selection leads to increased vigour within the species. This sorting out of the individuals with useful variations is called as natural selection by Darwin.<\/p>\n
\nBiodiversity is important to mankind because we obtain useful things from it but beyond the material need, it also plays a significant role in our cultural life. Hence, biodiversity acts as a source of inspiration as people admire its intrinsic beauty and it also motivates poets, writers, etc. Biodiversity gives a cultural identity in terms of festivals and rituals we have in terms of religion as well, some plants are also considered to be sacred like tulsi, peepal etc. Similarly many animals are worshipped and have religious value described in the scriptures. For example, Kaamdhenu and feeding monkeys acts as a representative of Lord Hanuman.<\/p>\n
\nRicha will try to convince her family by explaining them about the phenomenon of sex determination in human beings in which male possesses one X and one Y chromosome while, a female has two XX-chromosomes. If an ovum fertilises with a sperm carrying X-chromosome, the zygote develops into a female (XX) while, if an ovum fertilises with sperm carrying Y-chromosome, the zygote develops into a male (XY).Hence, it shows that the genetic make up of sperm, which fertilises the ovum determines the sex of a child. Thus, it is not right to blame a mother for the birth of a girl child as it is a by chance phenomenon because there are both 50-50% chances of having either a male or a female child each time a female becomes pregnant.<\/p>\n
\nSelection of recombinants due to inactivation of antibiotics is a laborious process as it requires:<\/p>\n\n
\nOR
\n<\/strong>(1)
\n![\"CBSE](\"https:\/\/www.aplustopper.com\/wp-content\/uploads\/2018\/12\/CBSE-Sample-Papers-for-Class-12-Biology-Paper-6.5.png\")
\n(2) Morula is formed in isthmus, the upper portion of an oviduct. The diploid zygote is formed by the fusion of haploid sperm and ovum which rapidly moves by cleavage through the isthmus of the oviduct by mitotic division. As a result of which blastomeres of 2, 4, 8, 16 daugther cells are produced. This embryo with 8-16 blastomeres is called morula.<\/p>\n
\nMOET or Multiple Ovulation Embryo Transfer technology is the technique commonly used for herd improvement, i.e., a group of animals that live together or are kept together as a livestock.
\nThe steps involved in the method are as follows.<\/p>\n\n
\n
\n<\/strong>1. It is used as a source of energy for cooking and for the purpose of heating as well.
\n2. Reduces greenhouse effect.<\/p>\n
\n(1) To force a recombinant DNA into host cells, a cloning vector must possess the following characteristics:
\n(a) (Origin of replication (ori):<\/strong> The process of replication begins from here where any piece of DNA when linked to this sequence is made to replicate within the host cells.<\/p>\n
\n1. The enzymes present in the cytoplasm of the cell makes it difficult for DNA to pass through and reach cell membrane.
\n2. Secondly cell membranes are made up of phospholipids and cholesterols which make DNA molecule impermeable being hydrophilic.
\nOR<\/strong><\/p>\n\n