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Neo Darwinism Theory of Evolution Definition and Major Postulates

  • Also called as Modern Synthetic Theory of Evolution, Modern Synthesis or Neo Darwinian synthesis.
  • Definition: It is the modified elaborated version of Darwinism with addition of data from Mendelian genetics, molecular biology, population genetics and biological species concept. According to Neo Darwinism, evolution occurs by natural selection of genetically modified characters or genotypes.
  • August Weismann used the term Neo-Darwinism for the first time and he incorporated his theory of Germplasm into Darwin's theory of evolution by natural selection.
Neo Darwinism Theory of Evolution - Definition and Major Postulates
The Major Postulates of Neo Darwinism
1. The unit of evolution is population not species. Each species comprises of many local populations.
2. It is the gene pool of the population that undergoes variation and not the individuals
3. Natural selection refers to the differential amplification of fittest genes and genotypes that is best suited to an environment and natural selection is not the only cause of evolution.
4. The formation of new species is by the accumulation of inherited random mutations and also by genetic recombination occurring due to independent assortment, fertilization and crossing over.
5. The major factors responsible for organic evolution include mutation, genetic recombination, natural selection and reproductive isolation.
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CSIR UGC NET JRF Life Sciences - Plant Developmental Biology (Unit 5 - Developmental Biology)

Plant Development Biology - Questions from Morphogenesis and organogenesis in plants:
1.Floral organ development is controlled by overlapping expression of ‘A’ class, ‘B’ class and ‘C’ class genes in different whorls. In an Arabidopsis mutant, the flowers had sepals, sepals, carpels and carpels in the four whorls. Mutation in which one of the following is the cause for the mutant phenotype? (CSIR Life Sciences Dec, 2015)

1. ‘A’ class gene alone
2. ‘B’ class gene alone
3. ‘A’ and ‘B’ class genes
4. ‘C’ class gene alone
 Ans: 2. ‘B’ class gene alone
2. Sperm cell behaviour during double fertilization in Arabidopsis can be stated as follows. Identify the INCORRECT statement: (CSIR Life Sciences June, 2016)
1. Pollen tube bursts and discharges sperm cells.
2. Sperm cells produce pollen tubes and enter into female gametophyte.
3. The receptive antipodal cells break down when pollen tube enters the
female gametophyte.
4. One sperm nucleus fuses with the egg cell and the other fuses with the central cells
 Ans: 2 and 3
Plant Developmental Biology Questions
3. Rhizobial genes that participate in legume nodule formation are called nodulation (nod) gens. The nodD-encoded protein  (CSIR Life Sciences June, 2016)
1. is an acetyl transferase that adds a fatty acyl chain to the Nod factor.
2. binds to the nod box and induces transcription of all nod genes.
3. catalyzes the linkage of N-acetyl glucosamine residues.
4. influences the host specificity of Rhizobium.
 Ans: 2. binds to the nod box and induces transcription of all nod genes.
4. Which one of the following statements is WRONG? (CSIR Life Sciences June, 2016)
1. The megasporocyte develops within the megasporangium of the ovule
2. Megasporocyte undergoes meiosis to produce four haploid megaspores
3. All the four megaspores undergo several mitotic divisions to form female gametophyte in most angiosperms
4. Female gametophyte is haploid
Ans: 3. All the four megaspores undergo several mitotic divisions to form female gametophyte in most angiosperms
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CSIR Life sciences Animal Developmental Biology Questions (Unit 5- Developmental Biology)

Questions includes: Basic concepts of development, Gametogenesis, fertilization and early development, Morphogenesis and organogenesis in animals 

1. In chick, development of wing feather, thigh feather and claws depends on epithelial specificity conferred by induction from mesenchymal components from different sources of the dermins. This may be attributed to? (CSIR Life Sciences Dec, 2015)
1. Autocrine interaction
2. Regional specificity of induction
3. Receptor activation by hormones
4. Inactivation of genetic interaction
 Ans: 2. Regional specificity of induction
2. Alveolar cells of the lung arise from which one of the following layer(s)? (CSIR Life Sciences Dec, 2015)
1. Mesoderm
2. Endoderm
3. Ectoderm
4. Both ectoderm and endoderm
 Ans: 2. Endoderm
3. Migration of individual cells from the surface into the embryo’s interior is termed as (CSIR Life Sciences Dec, 2015)
1. ingression
2. involution
3. invagination
4. Delamination
 Ans: 1. ingression
4. Bones of vertebrates are derived from embryonic (CSIR Life Sciences June, 2016)
1. ectoderm
2. epiderm
3. mesoderm
4. Endoderm
 Ans: 3. mesoderm
5. During development, if a cell has committed to a particular fate, it is said to be  (CSIR Life Sciences June, 2016)
1. pluripotent
2. totipotent
3. determined 
4. Differentiated
 Ans: 3. determined 
CSIR Life sciences Animal Developmental Biology Questions

6. The initial dorsal-ventral axis in amphibian embryos is determined by  (CSIR Life Sciences June, 2016)
1. the point of sperm entry.
2. gravity.
3. the point of contact with the uterus.
4. genetic differences in the cells.
 Ans: 1. the point of sperm entry.
7. Apical ectodermal ridge induction is essential for tetrapod limb development. Which one of the following is NOT essential for the formation of a functional limb? (CSIR Life Sciences June, 2016)
1. Tbx genes and Wnt
2. Androsterone
3. Apoptotic genes
4. Fibroblast growth factor

 Ans:2. Androsterone
8. Certain proteins or mRNAs that are regionally localized within the unfertilized egg and regulate development are called  (CSIR Life Sciences June, 2016)
1. gene regulators.
2. morphometric determinants.
3. cytoplasmic determinants. 
4. mosaic forming factors.
Ans: 3. cytoplasmic determinants. 
9. Cell to cell communication is important in development of an organism. The ability of cells to respond to a specific inductive signal is called  (CSIR Life Sciences June, 2016)
1. Regional specificity of induction
2. Competence
3. Juxtracrine signalling
4. Instructive interaction
Ans:2. Competence
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CSIR Life sciences Cancer and Cell Signaling Questions (Unit 4- Cell Communication and Cell Signaling)

Questions on Cancer Biology (Oncology)
1. The mutation in an oncogene falls under which of the following classes? (CSIR Life sciences,June 2016)
 1. Loss of function mutation
 2. Frame shift mutation
 3. Gain of function mutation
 4. Dominant negative mutation
 Ans:  3. Gain of function mutation
2. Which one of the following best defines an oncogene? (CSIR Life sciences,June 2016)
1. An oncogene never codes for a cell cycle protein, which promotes cell proliferation.
2. Oncogenes are always involved in inherited forms of cancer.
3. An oncogene codes for a protein that prevents a cell from undergoing apoptosis.
4. An oncogene is a dominantly expressed mutated gene that renders a cell advantageous towards survival. 
Ans: 4. An oncogene is a dominantly expressed mutated gene that renders a cell advantageous towards survival. 
3. Which of the following events will NOT usually lead to transformation of a normal cell into a cancer cell? (CSIR Life sciences,June 2016)
1. Gain of function of oncogenes
2. Loss of function of tumor suppressors
3. Gain of function of genes involved in nucleotide excision repair
4. Loss of function of pro-apoptosis related Genes
Ans: 3. Gain of function of genes involved in nucleotide excision repair
 CSIR Life sciences Cancer and Cell Signalling Questions (Unit 4 - Cell Communication and Cell Signaling)
Questions on Cell signaling
4. Which one of the following statements about receptor – enzyme is FALSE? (CSIR Life sciences,June 2016)
1. A receptor – enzyme has an extracellular ligand binding domain, a transmembrane domain and an intracellular catalytic (enzyme) domain.
2. Many types of receptor enzymes are found in animals.
3. The signal transduction pathways of receptor – enzyme involve phosphorylation cascades.
4. Receptor – enzymes interact directly with  intracellular G-proteins.
Ans: 4. Receptor – enzymes interact directly with  intracellular G-proteins.

5. In the above signalling cascade, which one of the following molecules is denoted by ‘B’? (CSIR Life sciences,June 2016)

1. STAT 5
2. SMAD 6
3. GSK3
4. SMAD 4
Ans: 4. SMAD 4
6. Cell to cell communication is important in development of an organism. The ability of cells to respond to a specific inductive signal is called (CSIR Life sciences,June 2016)
1. Regional specificity of induction
2. Competence
3. Juxtracrine signalling
4. Instructive interaction
Ans: 2. Competence

7. Which of the following is NOT a second messenger? (CSIR Life sciences,Dec 2015)
 1. Cyclic GMP
 2. Diacylglycerol
 3. Inositol triphosphate
 4. Phosphatidyl inositol

Ans: 4. Phosphatidyl inositol
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CSIR UGC JRF NET Life Sciences Immunology Questions (Unit 4 -Innate and Adaptive Immune system)

11. Which antibody is known to responsible for allergic reactions (CSIR Life sciences, June 2009)
a) IgM
b) IgA
c) IgE
d) IgD
Ans: c) IgE
12. Which of the following is not coded by MHC genes (CSIR Life sciences, Dec 2008)
a) glycoproteins
b) antigen presenting proteins
c) complements of complement pathway
d) immunoglobulins
Ans: d) immunoglobulins
13. Which is least likely to occur for removal of cancer cells? (CSIR Life sciences, Dec 2008)
a) Phagocytosis
b) complement fixation
c) T-cell based cytotoxicity
d) autophagy
Ans: d) autophagy
14. Which function is not related with Th1 cells (CSIR Life sciences, June 2009)
a) secretion of IL2
b) induce phagocytosis
c) activated B cells
d) promoting antibody binding to soluble antigens
Ans: d) promoting antibody binding to soluble antigens
15. Immunotoxins are (CSIR Life sciences, June 2009)
a) anti-toxins
b) antibody for specific antigen tagged with toxin
c) low immunogenic toxin
d) bacterial toxins
Ans: b) antibody for specific antigen tagged with toxin
 Immunology Videos

 16. Cytotoxic T cells express  (CSIR Life sciences, Dec 2015)
1. CD8 marker and are class II MHC restricted
2. CD4 marker and are class I MHC restricted
3. CD4 marker and are class II MHC restricted
4. CD8 marker and are class I MHC restricted
Ans: 4. CD8 marker and are class I MHC restricted  
17.Which of the following is NOT a cell adhesion protein?(CSIR Life sciences, Dec 2008)
 1. Cadherin
 2. Selectin
 3. Immunoglobulin (Ig) superfamily
 4. Laminin
Ans: 1. Cadherin
18. Following are some of the characteristics of MHC class I and class II molecules except one which is applicable only for MHC class I. Identify the appropriate statement. (CSIR Life sciences, 2016 june)
1. They are expressed constitutively an all nucleated cells.
2. They are glycosylated polypeptides with domain structure.
3. They are involved in presentation of antigen fragments to cells.
4. They are expressed on surface membrane of B cells
Ans: 1. They are expressed constitutively an all nucleated cells.
19. The secondary antibodies routinely used for the detection of primary antibodies in western blotting experiment are (CSIR Life sciences, 2016 june)
1. anti-allotypic
2. anti-idiotypic
3. anti-isotypic
4. anti-paratypic
Ans: 3. anti-isotypic
20. Which one of the following is a food borne toxin? (CSIR Life sciences, 2016 june)
1. Tetanus toxin
2. Botulinum toxin
3. Cholera toxin
4. Diptheria toxin
Ans: 2. Botulinum toxin
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CSIR UGC NET JRF Life sciences - Molecular Biology Questions (Unit 3- Fundamental Process)

UNIT-3. Fundamental Processes (DNA replication, DNA repair and recombination, RNA synthesis and processing, Protein synthesis and processing, Control of gene expression at transcription and translation level)
1. Which one of the following chemicals is a DNA intercalator? (CSIR Life sciences, Dec 2015)
1. 5-Bromouracil
2. Ethyl methane sulfonate
3. Acridine orange
4. UV
Ans: 3. Acridine orange

2. An antibiotic that resembles the 3’end of a charged tRNA molecule is: (CSIR Life sciences, Dec 2015)
1. Streptomycin
2. Sparsomycin
3. Puromycin
4. Tetracycline
Ans: 3. Puromycin
CSIR UGC NET JRF Life sciences - Molecular Biology Questions (Unit -3 Fundamental Process)
3.α-Amanitin is a fungal toxin which inhibits eukaryotic RNA polymerases. The three eukaryotic RNA polymerases show differential sensitivity to this toxin. Which one of the following order (higher to lower) is correct in respect of sensitivity towards α - amanitin? (CSIR Life sciences, Dec 2015)
1. RNA POL III > RNA POL II > RNA POL I
2. RNA POL II > RNA POL III > RNA POL I
3. RNA POL I > RNA POL III > RNA POL II
4. RNA POL II > RNA POL I > RNA POL III
Ans: 2. RNA POL II > RNA POL III > RNA POL I

4. In eukaryotic replication, helicase loading occurs at all replicators during (CSIR Life sciences, Dec 2015)
1. G0 phase
2. G1 phase
3. S phase
4. G2 phase
Ans: 2. G1 phase
5.Error-free repair of double strand breaks in DNA is accomplished by 
(CSIR Life sciences, June 2016)
1. non-homologous end-joining.
2. base excision repair.
3. homologous recombination.
4. mismatch repair.

Ans: 3. homologous recombination.
6. RNA interference is mediated by both siRNA and miRNA. Which one of the following statement about them is NOT true? (CSIR Life sciences, June 2016)
1. Both siRNA and miRNA are processed by DICER.
2. Both siRNA and miRNA usually guide silencing of the same genetic loci from
which they originate.
3. miRNA is a natural molecule while siRNA is either natural or a synthetic one.
4. miRNA, but not siRNA is processed by Drosha

Ans: 2. Both siRNA and miRNA usually guide silencing of the same genetic loci from which they originate.

7. Which of the following are NOT transcribed by RNA polymerase II? (CSIR Life sciences, dec 2016)
1. miRNA and some snRNA
2. miRNA and snoRNA
3. mRNA and snoRNA
4. tRNA and 5S rRNA

8 . RNA editing, a post-transcriptional process, is achieved with the help of guide RNA (gRNA).Which one of the following statements about the process is NOT true? (CSIR Life sciences, dec 2016)
1. g-RNA dependent RNA editing happens in the kinetoplast DNA
2. g-RNA is involved in chemical modification of t-RNA
3. This process involves insertion or deletion of uridines
4. Sequences edited once may be re-edited using a second g-RNA
Ans: 2. g-RNA is involved in chemical modification of t-RNA
9. Telomerase, a RNA-protein complex which completes the replication of telomeres during DNA synthesis, is a specialized  (CSIR Life sciences dec 2016)
1. RNA dependent DNA polymerase
2. DNA dependent DNA polymerase
3. DNA dependent RNA polymerase
4. RNA dependent RNA polymerase
Ans: 1. RNA dependent DNA polymerase

10. Consider a short double-stranded linear DNA molecule of 10 complete turns with 10.5bp/turn. The ends of the DNA molecule are sealed together to make a relaxed circle. This relaxed circle will have a linking number of (CSIR Life sciences dec 2016)
1. 105
2. 20.5
3. 10.0
4. 10.5
Ans: 3. 10.0
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CSIR UGC NET JRF Life Sciences - Cytology Questions (Unit 2-Cellular Organization)

CSIR NET LIFE SCIENCES - Cytology Questions - Unit 2. Cellular Organization  
 1. It takes 40 minutes for a typical E. coli cell to completely replicate its chromosome. Simultaneous to the ongoing replication, 20 minutes of a fresh round of replication is completed before the cell divides. What would be the generation time of E. coli growing at in complex medium? (Dec 2015)

a. 20 minutes
b. 40 minutes
c. 60 minutes
d. 30 minutes
Ans: a. 20 minutes
2. Glycophorin having one highly hydrophobic domain is able to span a phospholipid bilayer membrane only
a. once
b. twice
c. thrice
 d. four times
Ans: 1. once
3. Given below are events in the cell cycle.
(a) Phosphorylation of lamin A, B, C
(b) Phosphorylation of Rb (Retinoblastoma protein)
(c) Polyubiquitination of securin
(d) Association of inner nuclear membrane proteins and nuclear pore complex
proteins with chromosomes.

Which one of the following reflects the correct sequence of events in the mammalian cell cycle?
a. a->b->c->d
b. b->c->d->a
c. c->a->b->d
d. b->a->c->d
Ans: 4. b->a->c->d

4. Predominant interactions between phospholipids that stabilize a biological membrane include (June 2016)
a. hydrogen bonds and covalent interactions.
b. van der Waal and ionic interactions.
c. hydrophobic interactions and hydrogen bonding.
d. covalent and hydrophobic interactions.
Ans: c. hydrophobic interactions and hydrogen bonding.
CSIR UGC NET JRF Life Sciences - Cytology Questions (Previous Question Paper)
5 . Entry of enveloped viruses into its host cells is mediated by: (June 2016)
a. Only endocytosis
b. Both endocytosis and phagocytosis
c. Both endocytosis and membrane fusion
d. Only pinocytosis
Ans: c. Both endocytosis and membrane fusion

6 . Lateral diffusion of proteins in membrane can be followed and diffusion rate calculated by (June 2016)
a. Atomic force microscopy
b. Scanning electron microscopy
c. Transmission electron microscopy
d. FRAP (Fluorescence recovery after photobleaching)
Ans: d. FRAP (Fluorescence Recovery After Photobleaching)

7. Labelling of membrane spanning domain of any integral membrane protein in a given plasma membrane vesicle (without disrupting its structure) is successfully carried out by (June, 2016)
a. immunochemical methods.
b. metabolic labelling with radioisotopes.
c. hydrophobic photoaffinity labelling.
d. limited proteolysis followed by metabolic labelling.
Ans:  c. hydrophobic photoaffinity labelling.
8. Which one of the following describes the primary function of flippases? (dec, 2016)
a. Help in increasing lipid-protein interaction in the outer leaflet of the bilayer
b. Move certain phospholipids from one leaflet of the membrane to another
c. Localize more negatively charged membrane proteins in the lipid bilayer
d. Cause uncoupling of v-SNARES and t-SNARES after fusion of incoming vesicle
with target membrane
Ans:b. Move certain phospholipids from one leaflet of the membrane to another

9. Mitotic cyclin-CDK activity peaks in M phase. This is because
a. Mitotic cyclin is synthesised only in M phase.
b. Threshold level of mitotic cyclin accumulates only in late G2.
c. Cyclin subunit is activated by phosphorylation only in M phase.
d. The kinase subunit is activated by dephosphorylation only in M phase.

Ans: d. The kinase subunit is activated by dephosphorylation only in M phase.
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Explanation of Nobel Prize in Physiology or Medicine 2017- Molecular Mechanisms Controlling the Circadian Rhythm

The Nobel Prize in Physiology or Medicine 2017 was awarded jointly to Jeffrey C. Hall, Michael Rosbash and Michael W. Young for their discoveries of molecular mechanisms controlling the circadian rhythm.
What is Circadian rhythm? (Circa: around; dies: day in Latin)
To adapt to such changes in light and temperature, organisms have evolved an internal biological clock that anticipates day/night cycles and helps them optimize their physiology and behavior. This internally generated daily rhythm is known as circadian rhythm
Circadian Rhythm was first identified in plants (Mimosa). Later this internal biological clock was found to be present in all organisms including unicellular organisms, fungus, plants and animals.
Explanation of Nobel Prize in Physiology or Medicine 2017- Molecular Mechanisms Controlling the Circadian Rhythm

Period gene First gene identified dealing with Circadian Rhythm
Period gene was the first gene identified dealing with circadian rhythm. (Konopka and Benzer, 1971)
This gene was later cloned and sequenced  by Jeffrey Hall and
Michael Rosbash,, and Michael Young


Period (PER)  gene, mRNA & protein:
cycling of period mRNA and period protein
PER protein shuttles btw nucleus and cytoplasm
Accumulation of PER protein resulted in the reduction of period mRNA expression (negative autoregulatory feedback)
The peak of period mRNA levels
occurred early in the night, several hours before the peak in PER protein abundance.
TIM protein : coded by timeless gene can directly bind to PER protein. The interaction is critical for
PER protein nuclear accumulation and repression of the period gene.


How is Period and TIM gene activated?
 CLOCK (CLK) and CYCLE (CYC) protein interact with each other, and bind to specific elements in the period and timeless genes, thereby positively regulating their transcription.
TIM and PER act as negative regulators of CLK activity, and by this, the circadian feedback loop is closed.

How the transcription (Per mRNA) and translation (Per protein) synthesis is delayed or How Per & Tim protein is degraded?
DOUBLETIME protein a kinase : coded by double time (DBT) gene that phosphorylates PER
and increases its degradation. Light can activate the protein product of the cryptochrome cry gene (CRY) and promote its binding to TIM, leading to its degradation in the When morning arrives, TIM is degraded, leaving PER vulnerable to phosphorylation by DBT and subsequent degradation.


Transcription-Translation Feedback Loop (TTFL).
  The molecular mechanism that regulates Circadian rhythm is called Transcription-Translation Feedback Loop (TTFL).
 Accumulation of PER protein resulted in the reduction of period mRNA expression (negative autoregulatory feedback) called as translational feed back and transcription activators of Per gene, CLOCK (CLK) and CYCLE (CYC) is inhibited by TIM-PER protein accumulation in nucleus
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