CBSE Board Class 12 Biology Sample Papers 2011

Sample Paper – 2011
Class – XII
Subject – Biology

1. pyramids of numbre energy and biomass are mostly upright .is there exception to it.

2. when is the structure and composition of a community is expected to remain unchanged.

3. why hormone level increase many folds during pregnancy?

4. what is coitus interruptus.

5. aabb was crossed with aabb what would be the phenotypic ratio of progemy mention the term to denote kind of cross.

6. state chargaff rule

7. name bioactive molecule used as
   a. immuno suppressive agent in organ transplant patients.
   b. what is source of cyclosporin a?

8. expand lab .what is role of lab in human body?

9. name the type of interaction.
   a. copepods infests marine fishes.
   b.  define the above interaction.

10. name the hormones which are produced in gametogensis in males also give their function ( atleast 2)

11. a man with blood group a married a woman with blood group b their first child  is with blood gp o .workout possible blood gps in future progeny .

12. a. if sewage  water is dispose off in any river show its effect on bod
      b. write any two reasons for high bod in eutrophicated lake.

13. sex detrmination is based on particular chromosomes in both birds n humans.sate two point of difference b/w mechanism of sex detrmination.
     or
    draw schtematicallly a single polynucleotide .provide labels and direction

14. a. name the technique which is used in herd improvement
       b. give its significance
       c. name the hormone with which cow is adminstered.

15. a. what is metastasis.
       b. write one method to detect cancer.
       c. what is role of interferons.

16. complete the steps for sepration and isolation of dna fragments.
    a. dna fragment seprates in matrix of..........
    b. dna fragments are stained with.......
    c.dna  fragments aree stained under.......
    d. fragments are extruded from gel peice. this is called.......

17. why biotechnology is of great cocern ethically?

18. how has agrobacterium tumifacras been suitably modified to act as cloning vector?

19. in what refrence following terms are used
     a. lungs of planet.
     b.sixth extinction
    c. evil quartet

20. at what stage of life oogensis initated in human femalee?.when does oocyte complete ooogensis  and digramatically explain the process.

21. using punnnet square demonstrate the law of independent asssortment  in dyhybrid cross involving two heterozygous parents.

22.a. draw tarcriotional alongwith mention function of each
      b. what is splicing.

23. explain miller experiment /. which was the evidence to chemical evolution.

24. draw a flowchart to depict in multiplication of hiv virus in a host cell.

25. what are flocs state their role in effluent treatment and their ulimate fate in sewage treatment tank.

26.a. give digramatic representation of recombinat dna technology
     b. what is silencing of mrna 
                                 or
name the following
      a. 5'-gaattc-3' -----------
          3'-cttaag-5'
     b.  5'-g aattc-3'
         3'-cttaa g-5' ----------
     c. name the enzyme involed in the following...
         1. breaking the cell to realese dna and macromolecules .......
         2. repeated dna amplifications........

27. a what does the organisation geac checks with refrence to genetic engineering
      b. what does ecori stands for.
      c. what is role of molecular sicissors in recombinant dna technology.

28.a. what initatives were raken for reducing vehicular  air pollution in delhi?
     b. what is norm set by euro ii for petrol and disel vehicles.
                     or
    carbon cycle in nature is biogeochemical event. explain

29. how does the pollen mother cell develop into mature pollen grain .illustrate the stages with labelled digram
                    or
    show digramatically satges of embyronic development from zuygote upto implantation in humans

30. name the gene that constitute an operon. how does  lac operon get switched 'on' in the presence of lactose. what is    negative feedback
        or
    explain the technique dna fingerprinting in detail.