BOTANY

69
PAPER-II
Time Allowed Three hours Maximum Marks 300
The figures in the margin indicate full marks for the questions
Candidates should answer Question Nos. 1 and 5 which are compulsory and other three of the remaining questions, selecting at least one from each Section
Answer must be written in ENGLISH only
Neat sketches may be drawn, wherever required

SECTION-A
1.
Answer any three of the following in not more than 250 words each: 20x3=60

2.
Write critical notes on the following: 12x5=60


Synaptonemal complex


Chi-square test


Special types of chromosomes


Genetic code


Geological evidences of organic evolution




Explain elaborately how the linkage and cross-over data can be utilized for construction of a chromosome map.'
What is cell cycle? Discuss the molecular mechanism that controls the various steps of cell cycle.
Explain with proper example how the pattern of sex-linked inheritance of a character differs from that of a normal Mendelian inheritance.
Give an plants. account of the cytoplasmic-genetic basis of male sterility in
Discuss the structural and functional details of ribosome.

[P.T.O.
3. Answer the following Differentiate between pleiotropic-gene action and multiple-gene action; pure-line selection and mass, selection; B-DNA and Z-DNA. 15x4=60 Deduce the experimental evidence in support of semiconservative mode replication of DNA molecule.
Explain the genetical basis of heterosis in crop plants.
Discuss with examples how the back-cross method of breeding can be used for the improvement of crop plants. .
4. 12x5=60Answer the following Explain the mechanism of action of physical mutagens. Discuss the various steps involved in DNA-recombinant technology. Explain the cytological evidence in support of crossing-over. •
Define translocation. Discuss the behavioural pattern of meiotic chromosomes in a translocation heterozygote. Discuss the physical and chemical organization of plant cell wall.
SECTION-B
5. Answer any three of the following in not more than 250 words each: 20x3=60 Give an account of the cyclic and non-cyclic photophosphorylation in plants. Give schematic diagrams and chemical reactions wherever necessary.
What are the different ecosystems prevailing on the earth? Explain fully each of them citing examples. Discuss the mechanism of passive absorption and active tr'ansport of nutrients in plants.


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6. Answer the following questions 15x4=60

Explain sequentially the chemical reactions and energy flow involved during the tricarboXylic acid cycle.


What do you mean by seed dormancy? Explain the'various methods adopted for breaking dormancy in seeds.


How do you differentiate among rare, threatened and endangered pla111s? Discuss the different factors responsible for endemism in plants.


What is water potential? Explain how this phenomenon helps the
movement of water in plants.

7. Answer the following 12x5=60

Give an account of the Dixon's theory of ascent of sap, mentioning its merits and demerits.


Give an account of the process by which the plants convert the atmospheric nitrogen into their usable forms.


Discuss the importance of the following elements in plant life


Boron


Manganese


Sulphur


Describe the pathway through which the carbohydrates undergo breakdown for the formation of pyruvate.


What are the secondary plant products? an account of their chemical nature and importance.


8. Write notes on, the following 12x5=60

Chemosynthesis


Global warming


Electron-transport chain


Senescence


Auxins and their importance



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