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12th Standard English Medium Biology Reduced Syllabus Annual Exam Model Question Paper - 2021

12th Standard

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Biology

Time : 02:45:00 Hrs
Total Marks : 70

    Part I

    Answer all the questions.

    Choose the most suitable answer from the given four alternatives and write the option code with the corresponding answer.

    15 x 1 = 15
  1. ______ is a seasonal breeder.

    (a)

    Poultry

    (b)

    Honey bees

    (c)

    Deers

    (d)

    Rabbit

  2. Identify the correct statements from the following

    (a)

    Chlamydiasis is a viral disease

    (b)

    Gonorrhoea is caused by a spirochaete bacterium, Treponema palladium

    (c)

    The incubation period for syphilis is is 2 to 14 days in males and 7 to 21 days in females

    (d)

    Both syphilis and gonorrhoea are easily cured with antibiotics

  3. Which is NOT a part of transcription unit?

    (a)

    Promoter

    (b)

    Operator

    (c)

    Structural gene

    (d)

    Terminator

  4. The Neanderthal man had the brain capacity of

    (a)

    650 – 800cc

    (b)

    1200cc

    (c)

    900cc

    (d)

    1400cc

  5. What gases are produced in anaerobic sludge digesters?

    (a)

    Methane and CO2 only

    (b)

    Methane, hydrogen sulphide and CO2

    (c)

    Methane, hydrogen sulphide and O2

    (d)

    Hydrogen sulphide and CO

    (e)

    Consumption of organic matter in the water is higher by the microbes

  6. Which of the following is correct for r-selected species

    (a)

    Large number of progeny with small size

    (b)

    large number of progeny with large size

    (c)

    small number of progeny with small size

    (d)

    small number of progeny with large size

  7. Van't Hoffs rule describes the impact of ____________ on the environment.

    (a)

    Light

    (b)

    Temperature

    (c)

    Water

    (d)

    Soil

  8. In monoecious plants,

    (a)

    Both autogamy and geitonogamy are prevented

    (b)

    Both autogamy and geitonogamy are takes place

    (c)

    Autogamy takes place preventing geitonogamy

    (d)

    Autogamy is prevented whereas geitonogamy takes place

  9. Due to incomplete linkage in maize, the ratio of parental and recombinants are

    (a)

    50:50

    (b)

    7:1:1:7

    (c)

    96.4: 3.6

    (d)

    1:7:7:1

  10. Statement 1: Pairing of homologous chromosome is called as syndesis.
    Statement 2: Proterminal synapsis occurs from telomeres.

    (a)

    Statement 1 is correct and Statement 2 is incorrect

    (b)

    Statement 1 is incorrect and Statement 2 is correct

    (c)

    Both the statements are correct

    (d)

    Both the statements are incorrect

  11. The time duration for sterilization process by using autoclave is ______ minutes and the temperature is _______

    (a)

    10 to 30 minutes and 125° C

    (b)

    15 to 30 minutes and 121° C

    (c)

    15 to 20 minutes and 125° C

    (d)

    10 to 20 minutes and 121° C

  12. Environment of any community is called

    (a)

    Paratope

    (b)

    Ecotype

    (c)

    Opitope

    (d)

    Biotope

  13. Which one ofthe following is not a functional unit of an ecosystem?

    (a)

    Productivity

    (b)

    Conductivity

    (c)

    Energy flow

    (d)

    Decomposition

  14. Assertion (A): Ozone acts as a natural sunblock.
    Reason (R): UV rays reaching the earth are deviated from earth.

    (a)

    A is correct R is incorrect.

    (b)

    A is incorrect R is correct.

    (c)

    R explains A.

    (d)

    Both A and R are incorrect.

  15. The only cereal that has originated and domesticated from the New world.

    (a)

    Oryza sativa

    (b)

    Triticum asetumn

    (c)

    Triticum duram

    (d)

    Zea mays

  16. Part II

    Answer any 6 of the questions. Question no.24 is compulsory.

    6 x 2 = 12
  17. Define Vivipary.

  18. How is polyspermy avoided in humans?

  19. State the allelic forms of I gene and mention its chromosomal location.

  20. What is a replication fork?

  21. Differentiate between infectious and non-infections disease.

  22. Why are some organisms called as eurythermals and some others as stenohaline ?

  23. Discuss the gross primary productivity is more efficient than net primary productivity.

  24. What is toddy?

  25. How does immune system work?

  26. Part III

    Answer any 6 of the questions. Question no.33 is compulsory.

    6 x 3 = 18
  27. Rearrange the descent in human evolution
    Austrolopithecus → Homo erectus → Homo sapiens → Ramapithecus → Homo habilis.

  28. Write the key features of organic farming.

  29. Give the diagnostic characters features of a Biome

  30. Point out the biosphere reserves in Tamil Nadu.

  31. Why does the zygote divides only after the division of Primary endosperm cell.

  32. In Drosophila melanogaster, there are four pairs of chromosomes. If there occurs chromosomal aberrations resulting in trisomic and monnsomlc condition, what will be the chromosomal count? Write the correct chromosomal count against respective chromosomal aberration.

  33. What is thermal stratification? Explain its types.

  34. How do forests help in maintaining the climate?

  35. Give an account on clonal selection.

  36. Part IV

    Answer all the questions.

    5 x 5 = 25
    1. Describe the structure of human ovary.

    2. Write the preventive measures of STDs.

    1. Explain the transcription process in prokaryotes with needed diagram.

    2. Distinguish tenuinucellate and crassinucellate ovules.

    1. Explain Dihybrid cross in pea plant.

    2. Write the protocol for artificial seed preparation.

    1. Point out any five morphological adaptations of epiphytes.

    2. Generally in summer the forest are affected by natural fire. Over a period of time it recovers itself by the process of successions .Find out the types of succession and explain.

    1. What are the effects of deforestation and benefits of agroforesty?

    2. Give a detailed account on anyone fibe yielding plant.

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