HBSE 12 Class Biology Paper 2019

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HBSE 12 Class Biology Paper 2019

HBSE 12 Class Biology Paper 2019

Class ⇨ XII

Subject ⇨ Biology

Time ⇨ 3 Hrs.                                                            M.M⇨ 60

Section ⇨ A


1. (i) In which of the following organisms asexual reproduction occurs by zoospore? 1.

(a) Yeast (b) Chlamydomonas (c) Penicllium (d) Hydra.

(ii) Which one of the following trait of pea plant studied by Mendel’s dominant? 1.

(a) Axial flower position (b) Green seed color (c) Wrinkled seed shape (d)  Yellow pod color.

(iii)In which phase of cell cycle DNA replication take place? 1.

(a) S -phase (b) G -phase (c) G2 -phase (d) M -phase.

(iv) Which naturalist had said that evolution of life from occurred by use and discuss of organs? 1.

(a) Louis Pasture (b) De vries (c) Landmarck (d) Aedes mpquito.

(v) Which one is the following is the vector of Chikungunya disease? 1.

(a) Anopheles mosquito (b) House fly (c)Culex mosquito (d) Aedes mpquito.

(vi) Which high yielding semi-dwarf variety of rice is developed in Taiwan? 1.

(a) Taichung Native-I (b) Ratna (c) Jaya (d) I R-8

(vii) Brewer’s Yeast is used in the preparation of industrial product: 1.

(a) Bread (b) Ethanol (c) Penicillin (d) Acetic acid.

(viii) Which gas is responsible for the degradation of the ozone layer in the stratosphere? 1.

(a) Carbon dioxide (b) CFCs (c) Sulphur dioxide (d) Nitrous oxide.

(ix) What is vegetative propagation?

(x) What is tubectomy?

(xi) What is trisomy?

(xii) What is secondary productivity in an ecosystem?

HBSE 12 Class Biology Paper 2019

Section ⇨ B


2. Give an example of hormone-releasing IUDs. How does it help in preventing pregnancy? 2.

3. Are the wings of a bird and butterfly homologous or analogous organs? Explain and state the kind of evolution they represent. 2.

4. A patient is down with typhoid fever. List the symptoms that confirm this infection. Name the causative pathogen.

5. State the disadvantages of inbreeding among cattle. How it can be overcome?

6. Expand the name of the enzyme A.D.A. Why is this enzyme essential in the human body?

7. What is an adaptation? State the adaptations found in desert plants to minimize water loss through transpiration.

8. Under those circumstances, does the secondary succession begin? Why does it proceed faster than primary succession?

9. State any two uses of biodiversity in industrial products.

10. Why is the use of CNG in vehicles is better than diesel and petrol? Give any four reasons.

HBSE 12 Class Biology Paper 2019

Section ⇨ C


11. Why is a pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.3

12. What are baculoviruses? Explain their role in bio-control of pests? 3

13. Name the selectable markers in the cloning vector pBR 322? Mention of the role they play. 3

14. What are the transgenic animals? Explain the role of transgenic animals in biological products.

15. Explain with an example how do habitat loss and fragmentation cause extinction of plants and animals?

HBSE 12 Class Biology Paper 2019

Section ⇨ D


16. (i) Draw a labeled diagram of L.S. of an endospermic monocot seed.

(ii) Why is fertilization in an angiosperm referred to as double fertilization? Mention ploidy of the cells involved.

OR


(i) With the help of the diagram describe the stage of embryo development in a dicot flower plant.

(ii) Explain polyembroyny with an example.

17. When and where are primary oocytes formed in a human female? Trace the development of these oocytes till ovulation.

OR


(i) Explain the events taking place at the time of fertilization of an ovum in a human female.

(ii) Trade the development of zygote up to it’s important in the implantation in the uterus.

18. (i) Explain the mechanism od D.N.A. replication. Highlight the role of enzymes in this process.

(ii) Why is D.N.A. replication said to be semi-conservation?

OR


(i) How did Griffith explain the transformation of R – strain bacteria into S – strain.

(ii) Explain, how MacLeod, McCarty, and Avery determined the biochemical nature of molecules responsible for transforming R – strain bacteria into S -strain?

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