» Biology : CBSE Sample Question Papers

Biology Class-Xll (CBSE)
You are on questions of Section A,B,C,D

Max Marks : 70
Time allowed : 3 hrs

Section - A

Q.Nos. 1-8 are of very short answer type carrying 1 mark each. Answer them in one word/one sentence having 1-20 words each.

Q 1. What is meant by trisomic condition? 1 mark

Q 2. State the presence or absence of sinus venous in a fish and a mammal. 1 mark

Q 3. Which type of cartilage is present between vertebrae to allow limited movement? 1 mark

Q 4. Name any two breeds of wild rock pigeon that have been developed through artificial selection. 1 mark

Q 5. Which chromosomes are called autosomes? 1 mark

Q 6. When is a tumour referred to as malignant? 1 mark

Q 7. What are the two factors that contribute for the dissociation of oxyhaemoglobin in the arterial blood to release molecular oxygen in an active tissue? 1 mark

Q 8. Which one of the following is fatal unless oral rehydration therapy is administered:
(i) Whooping cough (ii) Cholera (iii) Tetanus 1 mark

Section - B

Q. Nos. 9-18 are of short answer type carrying 2 marks each. Answer them in approximately 20-30 words each.

Q 9. What are the two functions of DNA polymerase? 2 marks

Q 10. Stanley Miller and Harold C. Urey performed an experiment by recreating in the laboratory the probable conditions of the atmosphere of the primitive earth.

(i) What was the purpose of the experiment?
(ii) In what forms was the energy supplied for the chemical reactions to occur?
(iii) For how long was the experiment run continuously? 2 marks

Q 11. How does the mustard inflorescence differ from the banana inflorescence in arrangement? Give the technical term for each. 2 marks

Q 12. Name the basic nitrogenous catabolite of proteins produced in birds. In what form is it eliminated from their body? What is the advantage of this type of excretion? 2 marks

Q 13. Describe the theory of inheritance of acquired characters. Who disproved it experimentally? 2 marks

Q 14. Differentiate between morula and blastula of mammals. 2 marks

Q 15. What is the biological significance of Azolla pinnate in agriculture? 2 marks

Q 16. Give any two reasons to justify that ginger is a modified stem. 2 marks

Q 17. Define biogeography. How do Darwin’s Finches provide the biogeographical evidence in favour of evolution? 2 marks

Q 18. Explain the structural and functional significance of fovea in the human eye. 2 marks

Section - C

Q. Nos. 19-27 are of short answer type carrying 3 marks each. Answer them in approximately 30-50 words each.

Q 19. What is meant by R cells and S cells with which Frederick Griffith carried out his experiments on Diplococcus pneumoniae? What did he prove from these experiments? 3 marks

Q 20. Draw a diagram of the T.S. of a part of seminiferous tubule of testis of an adult human male and label any six parts in it.

Q 21. How does industrial melanism bring out the action of natural selection? 3 marks

Q 22. How does intestinal juice contribute in the digestion of proteins? What provides alkaline pH in the small intestine? 3 marks

Q 23. An mRNA strand has a series of codons out of which three are mentioned below.

(i) AUG, (ii) UUU and (iii) UAG
(a) What will these codons be translated into?
(b) What are the DNA codons that would have transcribed these RNA codons? 3 marks

Q 24. List any four symptoms shown by a Down’s syndrome afflicted child. Explain the cause of this disorder. 3 marks

Q 25. Answer the following with reference to the anatomy of a dicot stem :

(i) Where exactly are the cambial cells located in the vascular bundles?
(ii) What is the name given to such a bundle?
(iii) How are the xylem vessels arranged?
(iv) What type of cells constitute the pith? 3 marks

Q 26. Explain any three chemical barriers that offer a non-specific defence mechanism. 3 marks

Q 27. Trace the development of microsporocyte in the anther of a mature pollen-grain. 3 marks

Section - D

Q.Nos. 28-30 are long answer type carrying 5 marks each. Answer them in approximately 80 - 120 words each.

Q 28. In the case of snapdragon (Antirrhinum majus) a plant with red flowers was crossed with another plant with white flowers. Trace the inheritance of flower colour up to the F₂ generation indicating the genotypesand phenotypes at each level. What special feature do you note in the genotypic ratios in the F₂ generation? 5 marks

Q 29. Name the hormone that regulates each of the following and mention the source of it :

(i) Urinary elimination of water

(ii) Storage of glucose as glycogen

(iii) Sodium and potassium ion metabolism

(iv) Basal metabolic rate

(v) Descent of testes into the scrotum 5 marks

Q 30. Describe the C₄ pathway in a paddy plant. How is this pathway an adaptive advantage to the plant? 5 marks

Biology Class-Xll (CBSE)
You are on questions of Section A,B,C,D

Max Marks : 70
Time allowed : 3 hrs

Section A

Q. Nos. 1-8 are of very short answer type carrying one mark each. Answer them in 1-20 words each.

Q1. Name the process in which bacteriophage picks-up a piece of DNA from one bacterial cell and transfers the same to another bacterial cell on infection.

Q2. Which fraction of soil water is readily available to plants for absorption?

Q3. What protects nitrogenase?

Q4. Name two plants that produce rhizomes.

Q5. Why is oxytocin called as ‘Birth Hormone’?

Q6. From which germ layers do the following organs differentiate :
(i) Kidney
(ii) Urinary bladder

Q7. What provides energy for abiotic synthesis on the primitive earth?

Q8. Name the two curable sexually transmitted diseases.

Section B

Q. Nos. 9-18 are short answer questions carrying 2 marks each. It is appropriate to answer them in about 20-30 words.

Q9. In most plants the terminal bud suppresses the development of lateral buds. What is this phenomenon called? Name the phytohormone that can promote the phenomenon.

Q10. Sieve tubes in angiosperms are associated with specialised parenchyma cells. Name those cells. How do they help sieve tube members?

Q11. How is the digested fat absorbed?

Q12. What are antagonistic muscles? Give one example.

Q13. Describe the methods of birth control by which fertilisation of ovum by sperm is prevented.

Q14. What is artificial selection in terms of evolution? Name one plant that has been produced as a result of artificial selection.

Q15. ‘Birds have evolved from reptiles’. How does palaentology provide evidence in support of the above statement?

Q16. Who discovered the coacervates? List the biological properties of co-acervates.

Q17. What is mycorrhiza? How does it act as biofertiliser?

Q18. Define autoimmune diseases. Give two examples.

Section C

Q. Nos. 19-27 are short answer questions carrying 3 marks each. It is appropriate to answer them in about 30-50 words.

Q19. What is transformation? Describe Griffith’s transformation experiment.

Q20. What are linked genes? Diagrammatically represent a cross between a white eyed female and red eyed male drosophila.

Q21. How does an excess of tryptophan cause ‘Switching off’ of the ‘tryptophan operon’?

Q22. If abiotic origin of life is in progress on a planet other than earth, what should be the condition there? Explain.

Q23. Trace the formation of Ovum from oogonium.

Q24. Describe the role of red blood cells in the transport of oxygen and carbon dioxide by blood.

Q25. Draw a diagram to show the internal structure of the human heart. Label six parts in all including at least three valves.

Q26. What is metastasis? List any four danger signals of cancer.

Q27. By providing one example for each category, classify the angiospermic flowers based on the position of ovary.

Section D

Q. Nos. 28 – 30 are long answer questions carrying 5 marks each. It is appropriate to answer them in about 80 – 120 words each.

Q28. Describe the process of DNA replication.

Q29. Specify how C₄ photosynthetic pathway increases CO₂ concentration in bundle sheath cells of sugarcane. How much is C₄ pathway more energy-expensive than C₃ pathway?

Q30. What is a synapse? How is the nerve impulse transmitted across a synapse?

Biology Class-Xll (CBSE)
You are on questions of Section A,B,C,D

Max Marks : 70
Time allowed : 3 hrs

Section A

Question Nos. 1-8 are of very short answer type carrying 1 mark each only. Answer them in 1-20 words each.

Q1. What induces parthenocarpy in grapes?

Q2. What is the term used for the regions of a gene which become part of mRNA and code for the different regions of the proteins?

Q3. The venous blood in the lung has a PCO₂ of 46 mm Hg. Should the alveolar PCO₂ exceed or be less than 46 mm Hg to result in diffusion of CO₂ from the blood into the alveolus?

Q4. Which part of the plant leaf is modified to form spines of Acacia and the sheath covering the leaf of Ficus elastica.

Q5. Name the enzyme that can break and reseal one strand of DNA.

Q6. What does the J-shaped growth curve of a population indicate?

Q7. What forms the cambial ring in a dicot stem during the secondary growth?

Q8. Name the principal mineral anion in the extracellular fluid.

Section B

Question Nos. 9 – 18 are short answer questions carrying 2 marks each. It is appropriate to answer them in about 20 – 30 words.

Q9. A mother with O type blood group has conceived. The expected blood group of the foetus is B. Will there be any problems to the mother or the foetus? If so, specify the problems?

Q10. What are the two types of fibres of the connective tissue? Differentiate between the two.

Q11. A farmer observed drops of water along the margins of leaves of tomato plants growing in his well-irrigated field on a winter morning. Give reasons for this occurrence. Why had the water drops appeared only along the leaf margins?

Q12. Give the scientific name of modern wheat. Why is it quoted as a typical example of rapid speciation?

Q13. Name any two of cyanobacteria and explain how they serve as main sources of bio-fertilisers.

Q14. What are the two striking observations when different stages of embryos of different classes of vertebrates are studied comparatively? How does this study support evolution?

Q15. (I) An animal should possess at least one out of the three possible characteristics to enable it to function as a ureotelic organism. List these characteristics.

(II) Which among the following is / are ureotelic animals :
Whale, camel, toad, shark.

Q16. Pick out the plant with whorled arrangement of leaves from the list given below and say why it is categorised so :
Neem; Nerium; Nepenthes.

Q17. How is elongation carried on during protein synthesis in a cell?

Q18. What category of pathogens causes poliomyelitis? How is crippling caused in the victim of this disease? How can this disease be prevented?

Section C

Question Nos. 19 – 27 are short answer questions carrying 3 marks each. It is appropriate to answer them in about 30 – 50 words.

Q19. To which category of cells do B-cells and T-cells belong? How do they differ from each other with reference to their formation and response to antigens?

Q20. How did Urey and Miller provide the conditions of primitive earth to prove the origin of life in their experiment?

Q21. Human skin colour is believed to be controlled by at least three separate genes.What do you call this type of inheritance?

(i) Suppose the gene are designated as A, B, and C and darkness is dominant over fairness, what shall be the genotypes of the darkest, fairest and intermediate skin colour?

(ii) What will be the total number of allele combinations in the gametes of a person heterozygous, all the three genes.

Q22. Draw a labelled diagram of the vertical section of human heart and show the pulmonary circulation in it by means of arrows.

Q23. Expand PEP. Where is it produced in C4 plants? What is its role in the biosynthetic process?

Q24. What type of striated muscles constitute the muscles of the eyeball? How is this specific type of muscle advantageous?

Q25. The base sequence on one of the strands of DNA is TACTAGGAT.
(i) Write the base sequence of its complimentary strand.
(ii) What is the distance maintained between the two consecutive paired bases in the DNA molecule?
(iii) Who contributed the base complementarity rule?

Q26. Name the parasympathetic nerve from the brain that innervates most of the visceral organs. List any four functions of this nerve.

Q27. Sometimes natural selection is not operative if the abnormal allele is somewhat advantageous to the individual. Explain this mechanism with a suitable example.

Section D

Question. Nos. 28 – 30 are long answer questions carrying 5 marks each. It is appropriate to answer them in about 80 – 120 words each.

Q28. What develops into a microspore mother cell in a flower? Trace the development of the cell into a pollen grain, which is ready for germination. Draw a labelled figure of a mature pollen grain.

Q29. What envelops the mammalian ovum preventing the entry of sperm into it easily? How does the sperm gain the entry eventually? What is the significance of the point of entry of the sperm?

Q30. Who demonstrated the semi conservative replication of DNA? Explain the experiment in detail.

Biology Class-Xll (CBSE)
You are on questions

Max Marks : 70
Time allowed : 3 hrs

Section A

Question Nos. 1-8 are of very short answer type carrying 1 mark each only.
Answer them in 1-20 words each.

Q1. At what stage is the embryo implanted in the uterus of the mother in the case of a test tube baby?

Q2. Human heart is Myogenic yet a parasympathetic nerve can reduce the heart rate. Name the nerve.

Q3. Which of the following diseases could be avoided by analysing the pedegree of parents
Klinefelter’s syndrome, Haemophilia, Amoebiasis.

Q4. Name the functional contractile unit of the muscle.

Q5. Name any two synthetic auxins used in agriculture.

Q6. What is pulvinus?

Q7. Name the fluid in which the membranous labyrinth of the inner ear floats.

Q8. In a round worm the volume of the body increases due to the growth of the body cells without increase in their number. What do you call this type of growth?

Section B

Question Nos. 9 – 18 are short answer questions carrying 2 marks each.
It is appropriate to answer them in about 20 – 30 words.

Q9. Why is the cleavage in mammals referred to as simple holoblastic?

Q10. Name the tissue that lines the urinary bladder. State any one advantage of this tissue being present there.

Q11. Draw a labelled diagram of the vertical section of an apple.

Q12. Why is the human male referred to as heterogametic?

Q13. What are the events that take place at the point of stimulation of an axon?

Q14. Write the transcribed m-RNA from the DNA strand with the base sequence of TAG TAC ACT. What is the specific term used for the last codon of the transcribed m-RNA in this case?

Q15. Why is blood group identification not required while transfusing serum?

Q16. The primitive earth had reducing atmosphere to enable abiotic origin of life. What put an end to it?

Q17. How does a sickle-cell carrier have an advantage over the rest of the human population in a Malaria ridden area?

Q18. What acts as an inducer in Lac Operon? How does it switch on the operon?

Section C

Question Nos. 19 – 27 are short answer questions carrying 3 marks each.
It is appropriate to answer them in about 30 – 50 words.

Q19. A Chrysanthemum plant with floral buds requires more than 12 hours of dark night time to flower. If the night is interrupted by white light for duration of an hour, will the flowers bloom the following morning?
Name the pigment that perceives the light stimulus for flowering.
Where is the pigment present in the plant and what are its two forms?

Q20. Define cancer. How are cancers broadly classified pathologically? Name one major cancer in women and one major cancer in men in India.

Q21. State Lamarck’s theory on evolution. Who disproved it and how?

Q22. A farmer has been advised to sow Soyabean seeds inoculated with a bacterial culture. Name the bacterium in the culture. How is this bacterium useful to the crop?

Q23. Draw a labelled diagram showing the longitudinal section of the phloem of an angiosperm with its components.

Q24. Name any three organs homologous to human hand. Why are they considered homologous?

Q25. Give the full form of ADH. Name the gland that secretes it. Under what condition of the body is it released? What is its role in forming hypertonic urine? What disease is caused due to the failure of secretion of this hormone?

Q26. Give one reason why lysozyme is considered an enzyme and not a hormone? How does it defend the body? Name any two secretions in humans, which contain lysozyme.

Q27. Draw a schematic diagram to show the continuous and discontinuous synthesis of DNA and label it.

Section D

Question Nos. 28 – 30 are long answer questions carrying 5 marks each.
It is appropriate to answer them in about 80 – 120 word each.

Q28. Where does spermatogenesis take place? Describe the stages of the process.

Q29. Where does cyclic photophosphorylation occur in the leaves? Explain the events in sequence. Why is the process referred to as cyclic?

Q30. Differentiate between linkage and sex-linked inheritance. Describe the mode of inheritance of any one sex-linked trait in humans.

Biology Class-Xll (CBSE)
You are on questions

Max Marks : 70
Time allowed : 3 hrs

Q.1 Which of the movable joint makes the hip joint ?

Q.2 Write the full form of tRNA.

Q.3 Mention any two factors by which the environment or the nature checks the pollution size.

Q.4 Give two examples of analogous organs from animals.

Q.5 Mention one difference in the structure of chlorophyll-a and chlorophyll-b.

Q.6 Name the source glands of glucagon and parathormone.

Q.7 Mention one difference between benign tumour and malignant tumour.

Q.8 Name any two structures in our body, which bear ciliated epithilium.

Q.9 A women travels in a crowded compartment along with people suffering from diabetes, influenza and amoebiasis. With which one of these diseases she is most likely to be infected during this journey and why ?

Q.10 Amongst pea tendrils, opuntia spines, lemon thorns and cucurbit tendril, which ones are homologous structures? Give reason.

Q.11 Describe one example of artificial selection.

Q.12 Mention two differences in the vascular bundles of sunflower and maize stems.

Q.13 Give any four examples of human reflexes.

Q.14 How were exact replicas of master plate obtained in Lederberg replica plating experiment?

Q.15 In humans, genetically the sex of the child is determined by the father and not by the mother. Explain.

Q.16 Describe how auxins are related with the bending of shoots towards the source of light ?

Q.17 Explain any two palaeontological evidences in favour of organic revolution.

Q.18 Distinguish between bacterial transduction and bacterial transformation.

Q.19 Mention four aspects in which uricotelism differs from ureotelism.

Q.20 Specify how a pentose phosphate is a CO2 acceptor in the dark reaction of photosynthesis.

Q.21 How would non-secretion of hydrochloric acid in our stomach affect food digestion ? Explain ?

Q.22 A farmer adds Azotobactor culture in the soil before sowing maize. How does it increase the yield of maize.

Q.23 Give one example of co-dominance in human genetics.

Q.24 Draw a labelled diagram of the longitudinal section of a pistil showing pollen germination.

Q.25 Describe the process of DNA replication.

Q.26 If abiotic origin of life is in process on a planet other than the earth, what would be the conditions then ? Explain them.

Q.27 Explain the structure of a mammalian heart.

Q.28 Give a labelled diagram of the sectional view of the duct system and the ovary of the reproductive organs of the human female.

Q.29 Describe the mode of infection, symptoms and preventive measure of Diphtheria, Tetanus and Measles.

Q.30 Describe tow important functions each of the elements P, B and S in green plants and also write the deficiency symptoms of any two of them.

Q.31 Describe how our brain gets a continuous supply of oxygen from the atmosphere.

Q.32 In an experiment a phenotypic ratio 3 : 3 : 1 : 1 was obtained in the offspring on crossing Yellow sed-Tall stem Yy Tt variety of pea plant with yellow seed-dwarf stem variety. Determine the accuracy of this data by punnet squre.