Gujarat Board Class 12 Biology Sample Papers 2011

Class XII 

Biology (Theory)

(Set-1)

Time allowed : 3 hours                                                                                   Maximum Marks: 70

General Instructions:

(i) All questions are compulsory.

(ii) This question paper consists of four Section A, B, C and D. Section A contains 8 questions of one marks each, Section B is of 10 questions of two marks each, Sections C is of 9 questions of three marks each and Sections D is of 3 questions of five marks each.

(iii) 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 weightage. A student has to attempt only one of the alternatives in such questions.

(iv) Wherever necessary, the diagrams drawn should be neat and properly labeled.

SECTION – A

1. At which ends do ‘capping’ and ‘tailing’ of hnRNA occur respectively?

2. The meicocyte of rice has 24 chromosomes. How many chromosomes are present in its endosperm?

3. BOD of two samples of water A and B were 120 mg/L and 400 mg/L respectively. Which sample is more polluted?

4.Name the unlabelled areas ‘a’ and ‘b’ of the pie chart representing biodiversity of vertebrates showing the proportionate number of species of major taxa.

5. Are the wing of a bird and the forelimb of a horse homologous or analogous?  Name the type of evolution that explains the development of such structures.

6. Name the type of interaction seen between whale and the barnacles growing on its back.

7. Which one of the following is used in apiculture: Hilsa, Apis indica, Sonalika

8. The following statements (i), (ii) and (iii) seem to describe the water-pollinated submerged plants. Which one of these statements 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.

SECTION – B

9. Name the source organism from which Ti plasmid is isolated. Explain the use of this plasmid in biotechnology.       2

10. (a) Explain the property that prevents normal cells from becoming cancerous.                                  2

      (b) All normal cells have inherent characteristic of becoming cancerous. Explain.                                    2

11. In the T.S. of a mature another given below identify “a” and “b” and mention their function.                           2

12. Name the category of codons UGA belongs to. Mention another codon of the same category. Explain their role in protein synthesis.     2

13. How do automobiles fitted with catalytic converters reduce air pollution? Suggest the best fuel for such vehicles.         2

14. List the specific symptoms of pneumonia. Name the causative organism.

                                OR

How does spleen act as a lymphoid organ? Explain.                                                                             2

15. How does the Mediterranean orchid Ophrys ensure its pollination by bees?                                 2

16. Highlight any four advantages of Genetically Modified Organisms (GMOs).                                     2

17. What is Colostrum? Why is it important to be given to the newborn infants?                                2

18.(a) Name the molecular ‘M’ that binds with the operator.

(b) Mention the consequences of such binding.

(c) What will prevent the binding of the molecule ‘M’ with the operator gene? Mention the event that follows.         2

SECTION – C

19.(a) Identify the figure.

(b) Name the initial cell from with this structure has developed.

(c) Draw he next mature stage and label the parts.                                            3

20. A particular species of wild cat is endangered . In order to save them from extiction, which is a desirable approach in situ or ex situ?

Justify your answer and explain the difference between the two approaches.

21. (a) What is EcoRI? What does ‘R’ represent in this?

(b) Give the palindromic nucleotide sequence recognised by it.

(c) Explain its action.                                                                           3

22.(a) Identify the polarity from a to a’ in the above diagram and mention how many more amino acide are expected to be added to this polypeptide chain.

(b) Mention the DNA sequence coding for serine and the anticodon of tRNA for the amino acid.

(c) Why are some un-translated sequence of bases seen in mRNA coding for a polypeptide? Where exactly are present on mRNA?                        3

23. Why is predation required in a community of different organisms?                                          3

24. (a) Name the virus that causes AIDS in humans.

     (b) Explain the sequence of events that follows when this virus attacks to cause immune deficiency in humans.                      3

25. In one family each of the four children has a different blood group. Their mother os group A and the father is group B. Explain this pattern of inheritance with the help of a cross along with the genotypes.                     3

                                                                   OR

Who proposed chromosomal theory of inheritance? Point out any two similarities in the behavior of chromosomes and genes.            3

26.



What do these pictures ‘a’ and ‘b’ illustrate with reference to evolution? Explain.                       3

27. Draw and complete the following model of carbon filling a, b, c, d, e and f.



SECTION - D

28. (a) Explain the observations of Meselson and Stahl when

    (i) they cultured E. coli in a medium containing 15NH4Cl for a few generations and centrifuged the content.

    (ii) they transferred one such bacterium to the normal medium of NH4Cl.

(b) What does the above experiment prove?

(c) Which is the first genetic material identified?                                           5

                        OR

Inheritance pattern of flower colour in garden pea plant and snap dragon differs. Why is the difference observed? Explain showing the crosses.                                                            5

29. (a) Draw a labelled diagram of a mature embryo sac of an angiosperm.

      (b) Why does a pollen grain possess two male gametes? Explain.                            5

                                           OR

Study the flow chart given below. Name the hormones involved at each stage and explain their role.

Ovulation

    ↓

Pregnancy  →  Lactation

   ↓

Placenta

   ↓

Foetal growth

   ↓

Parturition

30. (a) Why are engineered vectors preferred by biotechnologists for transferring the desired genes into another organism?

      (b) Explain how do “ori”, “selectable markers” and “cloning sites” facilities cloning into a vector.                      5

                                                     OR

(a) How is a transgenic tobacco plant protected against Meloidegyne incognitia?

(b) Explain the procedure of making such plants.                                        5