4/07/2017

CSIR NET LIFE SCIENCE COACHING CENTRE

Plant Physiology Analysis of CSIR NET Life Science Exam


Dr. MOHIT GUPTA

PLANT PHYSIOLOGY AND METABOLISM

ANALYSIS OF THE TRENDS OF CSIR-NET QUESTION PAPER....



BROAD ANALYSIS OF PLANT PHYSIOLOGY IN CSIR-NET EXAM
                                   
Hello Friends,
Its only a month left for CSIR-NET Exam and you all must be busy with final revisions and organization of the entire syllabus…..We at Grassroots thought it prudent to provide you with brief analysis of the entire Plant Physiology section and the recent trend of topics being asked…….
If we analyze the table below, we could clearly make out……that at least 10 – 12 questions are consistently being asked from plant physiology i.e. 6 – 7 questions in Part-C (nearly 30% of total to be attempted in Part-C) and 4 – 5 questions in Part-B………which could immensely contribute to ones success, at least students from pure sciences like M.Sc. Botany.


                    
Part - B
Part - C
Total
Dec 2014
7
5
12

June 2014
3
4
7

Dec 2013
4
6
10

June 2013
4
8
12

Dec 2012
4
7
11

June 2012
6
6
12




















TOPIC-WISE ANALYSIS OF QUESTIONS…

               Year
Topics
Dec 2014
June 2014
Dec 2013
June 2013
Dec 2012
June 2012
Part      B
Part C
Part B
Part C
Part B
Part C
Part B
Part C
Part B
Part C
Part B
Part C

H2O - Plant Relations

1






1
1



N2Metabolism




1

1

1

1
1

Photosynthesis

2
1
1
1
1

1
1

3
1
2
Phytohormones

2
1
2

1
1

2
1
1

1
Stress Physiology


1


1
1



1
1
1
Sensory Photobiology

1
1



1
1
1

1
1
1
Secondary Metabolites


1

1

1

1


1
1
Mineral Nutrition





1

1

2



Phloem Translocation






1




1

Respiration

1


1


1
1






The above table provides a clear cut analysis of the topic wise trend of questions being asked……
A) Phtosynthesis and Phytohormones are two topics which have been consistently asked .....but the questions asked cover a very wide and analytical perspective…so one needs a deep knowledge in these two areas….




In photosynthesis the questions are generally asked from the structure of Photosystems and the proteins involved, Water splitting complex, components, location and mechanism of electron transport chain i.e. z-cycle and its inhibitors……Alternate oxidase……Rubisco structure…..C-2 pathway i.e. photorespiration………and as usual C3, C4 & CAM pathway…but experimental…one should also know Aquatic CAM, CAM Idling etc…….Energetics of different pathways……….structure and role of different pigments their biosynthetic pathways…which is quite important.......so this topic  provides scope of very wide coverage….and is regarded core of plant physiology.




Phytohormones is one of the widest topics in plant physio……..and important too….we cannot discuss it in detail….but hormones like Auxins, cytokinins, gibberellins, ethylene, abscissic acid, jasmonic acid, brassinosteroids, polyamines etc…are all important………..their examples i.e. natural and synthetic…….biosynthetic pathways…….their receptors and signaling pathways…….as well as responses they regulate in plants…..some genetical studies etc
This topic due to its complexity and wideness needs last moment revision to remember…so I suggest that one should make proper notes and not leave it to books.




B) Other important topics to be covered are …….secondary metabolites, stress physiology, photo sensory biology and nitrogen metabolism….questions are regularly being asked.
secondary metabolites.…is one topic  which has no boundaries…and it is also part of plant biochemistry…..but the worst part is that the topic is not taught in most universities in India…as it is difficult to synthesize….at Grassroots we devote nearly 15-20 hours to this topic….secondary metab. has relevance to human health,  pharmaceutical and biotech industry..so topic becomes important…………..questions generally arise from biosynthetic pathways…e.g shikimic acid pathway, malonic acid pathway………mevalonic acid pathway……..synthesis of different alkaloid groups etc…….also focus on chalcones…….glucosinolates……cyanogenic glucosides…..saponins…….phytoalexins………golden rice etc…
Do get into habit of making personal notes….to organize data……so last moment revision becomes easier……don’t just leave information to books after studying…as most of us feel  lazy to write.




Photosensory biology…is a very advance topic and experimental too… …..this topic deals with perception of light by plants….as light is important for plant growth and devetlopment i.e. photomorphogenesis.

So which are different photoreceptors i.e phytohrome, cryptochrome, phototropins, UV-B receptors etc……what is the nature of these receptors and their absorption spectra…e.g

Q.  Plants have evolved with multiple photoreceptors, which can perceive specific wavelength of light. Which one of the following statements is correct about the photoreceptors?
1.       Phytochrome A can perceive far red and blue light.
2.       Phytochrome C can perceive far red light.
3.       Cryptochrome and phytochrome B are responsible for perceiving blue light.
4.       Phytochrome B can predominantly perceive for red light.

 Q. Light is perceived by various photoreceptors in plants. The photoreceptors predominantly   work at specific wavelengths of light. Some of the following statements are related to the  functions of plants photoreceptors.

(A) Phytochrome A predominantly perceives the red and far-red light.
(B) Phytochrome B predominantly perceives red light.
(C) Cryptochromes regulate plant development.
(D) Phototropins are involved in blue light perception and chloroplast movements.

Which one of the following combinations based on above statement is correct?
1. A, B and C                             2. B, C and D                       
3. C, D and A                             4. A, B and D

Study their signaling pathways……….responses they regulate….questions are also asked from different genes involved in their discovery and pathways…….and different responses  controlled by specific receptors.

Q.  Plants are able to perceive light through various photoreceptors and downstream genes. Which one of the following genes is not involved in light perception?
        1.PIF3.                                                                   2.NPR1.
        3.PHY E.                                                               4.CRY3.




Stress physiology…..is also a pretty advance topic …….and quite important for csir-net…….this topic is research based and has very wide horizons…..as we have biotic stress like….pathogen infection and abiotic stress like….osmotic and heat stress…….here we are concerned with abiotic stress….(as biotic stress is part of plant pathology)….

Abotic stress can be of different types…e.g. water or osmotic stress, flooding which creates…anaerobic conditions can lead to anoxic stress….heavy metal stress……salinity stress…….heat stress…….low temperature or freezing stress…… Now all these have different levels of adverse effects on plant physiology and metabolism…….what strategies does the plant adopt to overcome these specific stresses…….their signaling pathways……….one should also be thorough with concept of water poential (Ψw)…….concepts of oxidative stress and different anti-oxidants……e.g.

Q.  Water can move through the soil plant atmosphere continuum, only if water potential (Ψw) along that path

(1) Decreases                                                                (2) Increases
(3) Remains unchanged                                              (4) Fluctuates rapidly in either direction.

Q.  While studying the primary effect of different abiotic stresses on plants, a researcher observed water potential (ΦP) reduction and cellular dehydration. Which of the following combination of abiotic stresses may cause the observed effect?

1. Water deficit, salinity and chilling.                        2. Salinity, high – temperature and flooding.
3. Freezing, salinity and water deficit.                       4. Freezing, chilling and flooding.

Q.  Following are some statements related to osmotic stress in plants.

A. The accumulation of ions during osmotic adjustment is predominantly restricted to the vacuoles.
B. In order to maintain the water potential equilibrium within the cell, other solutes called as compatible solutes or compatible osmolytes accumulate in the cytoplasm.
C. Galactose is one of the compatible osmolytes involved in osmotic stress in plants.
B.  There are mainly four groups of molecules that frequently serve as compatible solutes.

Which one of the following combinations of above statements is correct?
1.  A, B and                          2. B, C and D                       3. A, B and D                       4. A, C and D




Nitrogen metabolism……again is an important topic, both from biochemistry or plant physiological perspective……N2 fixation can be asymbiotic or symbiotic………..both are important from exams view…….every thing cannot be discussed in blog as lot of research is happening on this area……….in our classroom programme we dhis eliver multiple lecture on this topic…….but do go through different enzymes involved..e.g. Nitrate reductase, Nitrite reductase, Glutamine synthetase, Glutamate synthase, Nitrogenase  etc……..as questions have been consistently asked….also to be noticed are different inhibitors of these enzymes…. coz they sell as herbicides….. ..energetics of nitrogen fixation…….also go through different genes involved in symbiotic N2 fixation.
One should also go through past questions being asked in exam to get the feel of depth and complexity. e.g.

Q. Nitrate reductase is an important enzyme for nitrate assimilation. Given below are some statements on nitrate reductase enzyme:
A. Nitrate reductase of higher plants is composed of two identical subunits.
B. One subunit of nitrate reductase contains three prosthetic groups.
C. One of the prosthetic groups attached to both subunits is heme.
D. One of the prosthetic groups complexed with pterin is magnesium.
Which of the following combination of statement on nitrate reductase mentioned above is correct?
1. A, B and C                       2. A, C and D                       3. B, C and D                       D. A, B and D




What’s noteworthy is that from the entire broad topic mentioned in syllabus……i.e.

F. Solute transport and photoassimilate translocation: Uptake, transport and translocation of water, ions, solutes and macromolecules from soil, through cells, across membranes, through xylem and phloem; transpiration; mechanisms of loading and unloading of photoassimilates.

Only questions from…..’ mechanisms of loading and unloading of photoassimilates’ i.e. phloem loading and unloading and ‘importance of some mineral ions in plants have been asked’…….so one can get a clear cut idea to plan the strategy.




Repiration.….which is a very important topic is generally covered under biochemistry or cell biology but in csir-net syllabus it has been placed under plant physiology………..i.e. one has to study it in plants perspective……..

Not many questions has emerged from this area………..even though it is quite wide……..every part of mitochondria is important………as questions may be asked in future………one should focus on Alternate oxidase and pentose phosphate pathway..and the bioenergetics.




So after the entire detailed analysis…….finally we could conclude that five topics i.e. Photosynthesis, Phytohormones, Secondary metabolites, Sensory Photobiology and Stress physiology should be focused more………..and other areas such as Nitrogen metab, Respiration, Plant-water relations etc…..could be laid little importance if one is short of time….

Do find time to look at past year papers……..so one could have a feel of the questions being asked…..and be mentally prepared to face them.

   ALL THE BEST…….AND DO REMEMBER 
CHANCE FAVOURS  A PREPARED MIND…….”

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