CBSE Biology Guess Paper Class XII 2009

http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com Guess Paper-2009 Subject – Biology Class -XII Time: 3 hours Max.Marks 70 General Instructions: 1. All questions are compulsory. 2. This question paper consists of four Sections A, B, C and D. Section -A contains 8 questions of 1 mark each, Section -B is of 10 questions of 2 marks each, Section -C has 9 questions of 3 marks each and Section D is of 3 questions of 5 marks each. 3. There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and all the three questions of 5 marks weight age. Attempt only one of the choices in such questions. 4. Wherever necessary, the diagrams drawn should be neat and properly labeled. Section A 1. How many eggs do you think were released by the ovary of a female dog, which gave birth to six puppies? How many eggs do you think would have been released by a human mother, who gave birth to identical twins? Would your answer change if the twins were born fraternal? [1] 2. The diagram below shows a human egg and a human sperm. [a] Why is the egg much larger than the sperm? [b] What is the significance of the two-labeled parts? [1] 3. If the frequency of the parental form is higher than 25% in a dihybrid test cross, what does it indicate about the two genes involved? Name the condition and the person who coined the term for it. [1] http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 4. The gene for haemoglobin Hb has two codominant alleles: HbA (the normal gene) and HbS (the mutated gene). How many phenotypes it can show? Name the three phenotypes. 5 Why are some fruits called as false fruits? Look at fruit below and label the Parts. [1] 6. How will you justify that placenta acts like an endocrine tissue? [1] 7 Red –green colour blindness is caused by a sex linked recessive allele. A colour-blind man marries a woman with normal vision whose father was colour-blind. What is the probability that their daughter will be colour – blind? What is the probability that their son will be colour – blind? [1] 8 A human zygote has XXY sex chromosomes along with 22 pairs of autosomes. What sex will the individual be? [1] Section B 9. Do you think reproductive health has improved in our country in the past 50 years? If yes, mention four areas of improvement. [2] 10. Compare and contrast: isogamy and anisogamy. What are some examples of organisms that have each kind of gamete production? [2] 11. When a red flower of Antirrrhinum plant was crossed with a white flower of Antirrrhinum plant, the F1 offspring had pink flowers. Mention (a) the genotype of F1 plants and (b) the reason why it did not bear the parental red or white flowers? Or In a man brown eyes (B) are dominant over (b) and dark hair(R) dominant to red hair (r) . A man with brown eyes and red hair, whose father was blue eyed, marries a woman with blue eye and dark hair whose mother was red haired. They have four children. Give the genotype of the parents and phenotype and genotype of the children [2] 12. How is frame shift mutation different from point mutation? Give an example of point mutation. What causes mutations? [2] http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 13. Explain the four types of barriers of innate immunity. [2] 14. What conclusion can be drawn from the following pedigree chart? [2] 15. Identify the chemical structure. Give the scientific name of the plant from which it is obtained. Which two plant parts are used to extract this compound? Name the body system most affected by this compound. [2] 16. A fungi belonging to genera Microsporum are responsible for causing an Infectious disease in man. [i] Identify the disease [ii] Name the two other genera of fungi, which too cause the same disease [iii] Give two major symptoms of the disease. [2] 17. If a cross is made between a hybrid tall and red flowering plant (TtRr) with dwarf and white flowered (ttrr) what will be the genotype and phenotype of F1 generation? What is such a cross-called? [2] 18. A Chimpanzee holds objects with hand and an elephant with its trunk. Are these organs analogous or homologous? Why? Section C 19. Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe. Explain the [a] causes of cancer [b] Tecniques of detection and diagnosis [c] Treatment and cure . [3] 20. Show diagrammatically the stages of embryo development from zygote upto implantation in human being. [3] 21. Some species of Asteraceae have evolved a special mechanism, to produce seeds without fertilization. What it is called? How does it lead to polyembryony? Explain its significance. [3] http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 22. Alleles in a gene pool show the frequency according to the values given below p= 0.80 Allele freq. of A q= 0.20 Allele freq. of a p = 0.80 Allele freq. of A q= 0.20 Allele freq. of a What are the genotype and allele frequencies in the population? Is the population following Hardy-Weinberg equilibrium calculate the result? State four conditions under which the Hardy-Weinberg equilibrium may not be applicable. [3] 23. How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material? [3] 24. Differentiate between spermatogenesis and oogenesis. Or Expand STD. Name four diseases that are classified under this category. How do they pose a major threat to a healthy society? [3] 25. Acquired immunity is pathogen specific. Explain the different working mode of primary and secondary response in the body. [3] 26. What is DNA fingerprinting? On what principle does it work? Mention its two applications. [3] 27. Given below is sequence of the processed mRNA ready for Translation: 5’-AUG CUA UAC CUC CUU UAU CUG UGA –3’ a) What is the first codon technically known as and which amino acid does it code for? b) How many Amino acid residues will make the polypeptide chain corresponding to this amino acid.Write the no. of t-RNA molecules needed to translate the polypeptide chain? c) Write the sequence of the DNA strand that coded for the above mRNA. Section D 28. 1) Explain Cell mediated and Humoral Immune responses in detail. 2) Draw well labeled diagram of Immunoglobulin and explain its structure. [5] http://www.cbseguess.com/-------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com Or 1) Explain the life cycle of Malarial parasite . 2) Write the causative organism and 3) Vector of Malaria. Write 4 symptoms of the disease. 29. (a) Draw a longitudinal sectional view of a typical anatropous ovule to show the site where double-fertilization takes place. Label any four major parts of the ovule. [5] (b) How do the male gametes that are present in the pollen grains reach the site mentioned by you in part (a) to cause double fertilization? Or A thallasemic child needed repeated blood transfusions got infected by HIV. (i) Use a rough diagrammatic sketch and arrows to show how the virus increased in number. (ii)Why did the increased number of the HIV virus deteriorate the child’s immunity? (iii) Which diagnostic test showed that the infective virus was HIV? 30. Explain the major evidences of evolution briefly. Or In a medium where E.coli was growing, lactose was added, which induced the lacoperon. Then, why does the lac operon shut down after some time after the addition of lactose in the medium? Explain [5] Paper Submitted by: Anita Mishra Email anitamishrabbvp@gmail.com Phone No. 01596245552