Botany lecture notes

PITS: Ultra-structure, Classification & Functions: Simple & Bordered Pits (Similarities and Differences)


torus and margo pits

What are pits?

Pits are the characteristic depressions on the cell walls of plant cells. They act as the channels for the transport of water and minerals between adjacent cells. Pits of two neighboring cells are usually located opposite to each other and these opposite pits together are called pit pair. Each pit has a cavity called pit cavity. Pit cavity opens internally to the lumen of the cells. The pit cavities of a pit pair are separated by a thin membrane called pit membrane. Pit membrane composed of the middle lamella and the primary cell wall of corresponding cells.

What are primary pit fields?

Pits of primary and secondary cell wall show considerable differences. Well organized pits can be seen on the secondary cell wall. Pits of primary cell wall look like depressions on the cell wall. These depression like pits on the primary cell wall are called primary pit fields or primordial pits or primary pits. The cells with only primary cell wall, such as the parenchymatous cells of meristem, have only primary pit fields.

The sectional view of a primary cell wall with primary pit fields looks like ‘beads on string’ like appearance. This is because; the primary pit fields are formed as depression on the primary cell wall, moreover, the primary cell wall of primary pit fields is relatively thin than other portions. The wall of the primary pit field is traversed by many plasmodesmatal canals. Plasmodesmata provide cytoplasmic connectivity between adjacent cells. Through plasmodesmata, the protoplasm of living cells are interconnected.

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NET Life Sciences June 2016 Model Test Questions with Answer Key Part 3 (CSIR NET MCQ 05)


NET Life Sciences June 2016

CSIR JRF NET Life Sciences June 2016
CSIR NET Model Questions Part 5 (CSIR MCQ – 05)
Biology MCQ (Multiple Choice Questions in Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT JRF, GATE, ICAR NET, PG Entrance)


1. If offspring of heterozygous parents (Aa at a single locus) are 25 percent AA, 50 percent Aa and 25 percent aa, then all of the following are true except:

a.       The parents are diploid organisms
b.      The allele is recessive lethal
c.       The alleles assort independently
d.      The gametes combine at random

2. A honey bee colony consists of:

a.       Equal number of males and females with all able to reproduce
b.      Mostly males, with only a single male being able to reproduce
c.       Mostly females, with only a single female being able to reproduce
d.      Equal number of males and females, with none able to reproduce sexually

3. Carbon sequestration refers to:

a.       The sale of carbon credits in the international market
b.      The process of capture and long-term storage of atmospheric oxygen
c.       The release of carbon, as CO2, into the atmosphere
d.      The accumulation of carbon in the atmosphere

4. The reason for the melting of DNA double helix at specific temperature is:

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CSIR NET Life Sciences Exam June 2016 Model Questions with Answer Key Part 2 (CSIR NET MCQ 04)


net practice test june december 2016

CSIR JRF NET Life Sciences June 2016
CSIR NET Model Questions Part 4 (CSIR NET MCQ – 04)
Biology MCQ (Multiple Choice Questions in Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT JRF, GATE, ICAR NET, PG Entrance)


1. Bergmann’s rule refers to a general tendency of mammals to be

a. Large in size in colder areas of their distribution
b. Smaller in size in areas of their distribution
c. Darker-pigmented in warmer areas of their distribution
d. Lighter-pigmented in warmer areas of their distribution

2. EDTA is used as a :

a. Oxidizing agent
b. Reducing agent
c. Chelating agent
d. Both (b) and (c)

3. Which of the following element plays an important role in nitrogen fixation

a. Manganese
b. Molybdenum
c. Zinc
d. Copper

4. Pribnow box is the component of _______

a. Operators
b. Promoters
c. Enhancers
d. Activators

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CSIR NET Life Sciences June 2016 Model Questions with Answer & Explanations Part 1 (CSIR NET MCQ 03)


NET June 2016 Sample Questions

CSIR JRF NET Life Sciences June 2016
Model Questions Part 03 (CSIR NET MCQ – 03)
Biology MCQ (Multiple Choice Questions in Life Science)
(Sample/Model/Practice Questions for JRF/NET Life Science Examination, ICMR JRF, DBT JRF, GATE, ICAR NET, PG Entrance)


(1). Which of the following does not contribute to protein diversity?

a.       RNA editing
b.      RNA splicing
c.       RNA interference
d.      Alternative initiation of translation

(2). Enzymes act by:

a.       Increasing the activation energy for a reaction
b.      Lowering the activation energy for a reaction
c.       Increasing the free energy of the system
d.      Decreasing the free energy of the system

(3). A carbon footprint is

a.       A greenhouse gas emission
b.      A way to make accurate tracing of animal track
c.       The amount of carbon stored within a living thing
d.      The total amount of circulating carbon in the biosphere

(4). A messenger RNA is 336 bases long including the initiation and termination codon. The number of amino acids in the polypeptide translated from this is:

a.       110
b.      333
c.       111
d.      600

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Revised Fellowship Rates of CSIR JRF, SRF & RA, Latest 2016: CSIR Sanctioned (Official Order)


CSIR (Council of Scientific and Industrial Research)

No. 6/Fellowship(ENH)/2k14/EMR-I, dated 002/03/2016     

Revision of CSIR Fellowships/Associateships:

The Governing body (GB), CSIR in its 186th meeting held on 16th July 2015 considered and approved /sanctioned the proposal for enhancement of rates of stipend in respect of various CSIR fellowships such as CSIR JRF, CSIR SRF, CSIR RA Category I, II, III, along with GATE, SPM and CSIR Nehru Postdoctoral Research Fellowship in CSIR and its official laboratories. The enhanced rates of fellowships, effective from 1st October 2014 as follows:

revised fellowship rates csir net 2016

Further, the GB, CSIR ratified the revision of rates fellowship w.e.f 01/10/2014 notified vide CSIR OM No. 6/Fellowship(ENH)/2k14/EMR-I dated 19th March 2015 in respect of JRF-NET, SRF-NET, SRF-Direct, RA-I, RA-II and RA-III

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