Biology Exams 4 U

Biology Exam Preparation Portal. Preparing with U 4 ur exams...

Types of DNA binding domains with examples

DNA binding proteins interact with DNA by means of various structural motifs, and can stimulate or repress transcription of messenger RNA, depending on the properties and location of the DNA sequence to which they bind.

DNA binding proteins are classified into four types:- homeodomain proteins, zinc finger proteins, leucine zipper proteins, and helix loop helix proteins.
I) Homeodomain protein :
  • This protein consists of three linked alpha helices (helices 1, 2and 3). Helices 2 and 3 are arranged in a conspicuous helix turn helix motif.
  • A 60 amino acid long region (homeodomain) within helix 3 binds specifically to DNA segments that contain the sequence 5’ATTA3’
Examples of homeodomain proteins are:
a) Octanucleotide binding protein 1 (OCT –1), which regulates the histone gene H2B, the thymine kinase gene, and SnRNP genes
b) Octanucleotide binding protein 2 (OCT-2) , which regulates various immunoglobulin genes.
pituitary specific factor 1(Pit 1), which regulates the growth hormone gene, the thyroid stimulated hormone gene, and the prolactin gene.

II) Zinc finger protein
a) it has one alpha helix
b) It contains one zinc atom bound to four cysteine amino acids
c) It contains a hormone binding region
d) A 70 amino acid long region near the zinc atom binds specifically to DNA segments.
Zinc finger
Examples of  Zinc finger proteins are:
a) Transcription factor IIIA(TFIIIA), which engages RNA polymerase II to the gene promoter
b) Sp1(First described for its action on the SV40 promoter), which engages RNA polymerase II to the gene promoter by binding to the GC box
c) Glucocorticoid receptor, estrogen receptor, progesterone receptor, thyroid hormone receptor (erbA), retinoid acid receptor, and the vitamin D3 receptor.

III) Leucine Zipper Protein
  • It consists of of an alpha helix that contains a region in which every seventh amino acid is leucine, which has the effect of lining up all the leucine residues on one side of the alpha helix.
  • The leucine residues allow for dimerization of the two lecine zipper proteins and formation of Y shaped dimer.
  • Dimerization may occur between two of the same proteins(homodimers, eg., Jun-Jun) or two different proteins(heterodimers, eg., Fos-Jun).
  • It contains a 20 amino acid long region that binds specifically to DNA segments.
 Leucine zipper
Example of Leucine Zipper proteins are:
a)CCAAT/ enhancer binding protein (C/EBP), which regulates the albumin gene and the alpha 1 anti trypsin gene.
b) Cyclic AMP response element binding protein (CREB), which regulates the somatostatin gene and the proenkephalin gene.
c)Finkel osteogeneic sarcoma virus (Fos) protein, a product of of the c fos protooncogene, which regulates various genes involved in the cell cycle and cell transformation.
d)Jun Protein, a product of the c-jun proto-oncogene, which regulates various genes involved in the cell cycle and cell transformation.

IV) Helix loop helix protein (HLH)
  • It consists of a short alpha helix connected by a loop to a loner alpha helix.
  • The loop allow for dimerization of two HLH proteins and formation of Y shaped dimer.
  • Dimerization may occur between two of the same proteins (homo dimers) or two different proteins (heterodimers)
helix loop helix
Example of Helix loop helix proteins are:
a) MyoD protein, which regulates various gees involved in muscle development.
b) Myc protein, a product of the c myc protooncogene, which regulates various genes involved in the cell cycle.
Read More

Genetics Practice Problems Answers

1. The ability to taste a chemical called PTC is inherited as an autosomal dominant allele. What is the probability that children descendant from parents both heterozygous for this trait can taste PTC
a) 0
Answer. If you let T represent allele for the ability to taste PTC, then the cross would be Tt xTt. The Punnet square that follows show that ¾ of the offspring have ability to taste PTC (1/4 TT +1/2 Tt)

Ans: 3/4

2. Which of the following is true of gametes produced by an individual with genotype Dd?
 a)1/2D and 1/2D
b) 1/2D and 1/2d
c) 1/2Dd and 1/2dD
d)All Dd
Ans: d)All Dd

3. Three genes A,B,C  are located on a chromosome. The cross over percentage between A and B is 10% while that between A and C is 8% while that between B and C exhibits a cross over percentage of 18%. What will be the correct order of these genes in the chromosome.
a) XYZ
d)none of these
Ans: b)YXZ

4. What is the cross over percentage between two genes which are 10 map units apart?
a) 5%
b) 10%
c) 20%
d) 100%
Ans: The actual distance between two genes is represented as map unit. One map unit is equivalent to the percentage (%) of crossing over between the two genes.
Ans: b) 10%

5. For the cross AABBCCDd X AAbbCcDd, what is the probability that an offspring will be?
a) 1/16 b) 1/8  c) ¼ d) 3/8
It is not practical to make Punnett square for genotypes involving more than two genes. In this problem, you asked about the frequency of one specific offspring, AABbCcDd. To solve this problem, look at each gene separately.
·         Looking at the first gene, the parents are AA X AA and all offspring will be AA (frequency of 1)
·         For the second gene, BB X bb, all offspring will be Bb (frequency of 1)
·         For the third gene, the parents are CC x Cc, which products ½ CC and ½ Cc.
·         For the fourth gene, Dd x Dd, produces ¼ DD, ½ Dd and ½ dd
To find the probability of AA is 1, of Bb is 1, of Cc is ½, and of Dd is ½.
Then find the product of these frequencies.
·         For AABbCcDd the product is 1 X 1 X ½ X ½ =1/4
      Answer c) ¼ 

6. If you roll a pair of dice, what is the probability that they will both turn up a three?
The chance that one dice will turn up a three is 1 in 6, or 1/6.
For both dice to turn up a three, the probability is determined by multiplying the probability of each event happening independently, or 1/6 x 1/6 =1/36
Answer: d)1/36
Read More

ICAR ARS NET Model Questions on Agricultural statistics

1. Unit less measure of dispersion is
a) Range
b) Standard deviation
c) Mean deviation
d) CV

2. Which measure of central tendency requires data arrangement in ascending or descending order for its estimation?
a)Arithmetic mean
d)Harmonic mean

3. The most frequent occurred value of data or whose frequency is maximum is known as
a)Arithmetic mean
d)Harmonic mean
Measures of Central Tendency (Mean, Median, and Mode)
Points to remember: Measure of Central Tendency
4. In a symmetrical distribution of data which pair is correct?
a) Mean = Median=Mode
b) Mean > Median >Mode
c) Mean < Median<Mode
d) Mean = Median>Mode

5. To calculate the average speed, which item of central tendency is most suited?
b) Mode
c) Weighted HM
d) Weighed AM

6. Mean deviation is the least when calculated about (minimal property)
c)arithmetic mean
d)geometric mean

7. The hypothesis of committing type I error is known as
a) test of significance
b) level of significance
c) composite hypothesis
d) none of the above

8. For comparison of two means from independent samples which test is applicable
a) F test
b) t test
c) z test
d) chi square test

9. The coefficient of variation can be calculated by using the formula
a) Standard deviation / geometric mean x 100
b) Arithmetic mean /Standard deviation x 100
c) Square root of Standard deviation/ arithmetic mean x 100
d) Standard deviation / arithmetic mean x 100

10. Arithmetic mean and variance are always equal in
a) Binomial
b) Poisson distribution
c) Normal distribution
d) None of the above

Learn more:
1. d) CV
2. b)Median
3. c)Mode
4. a) Mean = Median=Mode
5. c) Weighted HM
6. a)median
7. b) level of significance
8. b) t test
9. d) Standard deviation / arithmetic mean x 100
10. b) Poisson distribution
Read More

ICAR ARS NET II Notification 2014

The Agricultural Scientists Recruitment Board (ASRB ) will hold a combined ARS-2014(Preliminary) Examination and NET-2014(II) during 22.9.2014 to 28.9.2014 in Online mode at 23 Centres across India in a staggered slot-wise examination format as per the Rules and Scheme of Examination indicated in this notification

Candidates are advised to read the notification carefully before filling the Online Application Form. 

Important Dates
  • ARS-2014(Preliminary) Examination and NET-2014(II) during 22.9.2014 to 28.9.2014 in Online mode.
  • The ARS-2014 (Main) Examination will be conducted on 28.12.2014.
  • The last date for filling up of online application form is 1700 hrs on 08.09.2014

Books to Refer for  ICAR ARS NET
Age limit
  •  For ARS-2014: A candidate must have attained the age of 21 years but not have attained the age of 32 years as on 01.08.2014. Age relaxation is admissible to the various categories as per rules. For details please refer to the Rule 2 of the Rules of the Examination .
  •  For NET-2014 (II): A candidate must have attained the age of 21 years as on 01.08.2014. There is no upper age limit for the National Eligibility Test. 
Application fee for ars net exam

Transaction charges for Debit Card/Credit Card/NEFT/Challan payment, as the case may be, have to be borne by the candidate. 

The fee must be paid online through the website:
i. Payment can be made through Debit Card/Credit Card from any Bank.
ii. Payment using the online Challan generated (in case of payment to be made using  Challan) can be made in any of the branches of the Syndicate Bank (list of the branches of Syndicate Bank can be obtained from the Branch locator link on : In such cases, the paid copy of the ASRB portion of the Online generated challan for application fee must be uploaded in the
relevant place of the application form without which the application will summarily be rejected. 
How to apply:
  • A candidate seeking admission to the Examination must apply online in the prescribed 
  • Application Form available on the website: .  A candidate must read the provisions contained in this Notification for Combined ARS-2014 and NET –2014 (II) carefully and abide by the same. A candidate must fulfil all the conditions of eligibility regarding age limits, educational qualifications, etc. prescribed for admission to the examination. 
  • The candidates are not required to attach copy of any of the documents / certificates in  support of their candidature at the time of submission of online application.
  • No request for change in any field i.e., Name, Father’s Name, Date of Birth, Gender, E-mail Id, Mobile No., Phone No., Category. etc. will be considered under any circumstances. Candidates are therefore advised to be very careful while filling up their application forms. 
Candidates are required to keep ready the following relevant details /information /documents:
a) Combined Notification for ARS Examination-2014 and NET-2014 (II).
b) Name ( as recorded in Secondary level Examination certificate)
c) Father’s name ( as recorded in the Secondary level Examination certificate)
d) Complete Address for Correspondence
e) Complete Permanent Address
f) Matriculation or equivalent Certificate
g) Master’s Degree Certificate/Provisional Degree Certificate/Transcript/ 
Marksheets; if available.
h) Doctorate Degree Certificate/Provisional Degree Certificate/Transcript/
i) Center opted for Combined ARS-2014 (Preliminary) Examination and
NET-2014 (II) (Please check the Examination Centers in this notification in
Appendix – I). 
j) Center opted for ARS-2014 (Main) Examination (Please check theExamination Centers in this notification in Appendix - II). 
k) Scanned copy of recent passport size photograph taken against white
background only of a maximum size of 150 kB in .jpg format only with theface covering at least 2/3
rd of the total space and taken without spectacles.
l) Scanned copy of signatures taken in Black/Blue ink on a white paper only in .jpg format only.
m) Debit Card/Credit Card details for online payment of fee.
n) Valid and active e-mail id.
Plan of NET 2014
  • Online Test Multiple Choice Questions (MCQ)  Demo Test *
  • Total Number of Questions: 150
  • Total Marks: 150
  • Duration of Test: 2 (Two) hours
Previous Question Papers Free (ICAR NET Preparation Resources)
First and foremost thing is to begin the preparation now onwards
"Wishing the very Best "
Biology Exams 4 U is preparing with U for your exam. Keep Visiting ………………….
Read More

Immunology Practice Test on Antibodies or Immunoglobulins

Immunoglobulins or specific antibodies or gamma globulins are blood proteins, which are found to be defensive only against the specific microorganisms, or their toxins that evoked that particular antibody. Immunoglobulins are glycoproteins, made up of 4 polypeptide chains (linked by disulphide bonds). There are two long chains, called heavy or H chains, and two short chains, called light or L chains. The four polypeptide chains are held together to form Y shaped molecule. The top two tips of this  shaped molecule bind to the specific antigens in a lock and key fashion, forming an antigen antibody complex.
1. Newborns
receive maternal B cells
respond to antigens as well as adults
have virtually a fully complement of maternal IgG antibodies
receive IgM antibodies from the mother through placental transfer
2. IgE
is bound together by J chain
is present in high concentration in serum
differs from IgG antibody because of its different H chains
bind to mast cells through its Fab region
3. IgA
is present in milk and saliva
is involved in hay fever
crosses the placenta
activates complement by the classical pathway
4. Human IgM
crosses the placenta
protects mucosal surfaces
is largely restricted to the circulation
is the antibody produced by high affinity plasma cells
5. Cells destined to become IgA producing plasma cells do not...
produce J chain
produce secretory component
migrate from mucosal areas on stimulation with antigen
home to any mucosal area
6. Immunoglobulin light chains
are joined chains by peptide bonds.
are present in the Fab fragment of IgG
all have the same amino acid composition.
are not found in every major immunoglobulin class
7. Ig heavy chains are
expressed by T cells
not important to binding of antigen
not glycosylated
encoded by a constant exon, variable exon, diversity exon and joining exon
8. The Fab portion of Ig
contains the J chain
binds to an Fc receptor
contains the idiotype of the Ig
mediates biological effector functions of Ab molecules
9. The Fc region of antibody
contains both heavy and light chains
is required for antigen binding
generally confers biological activity on the various molecules
is not a requirement for placetal transmission
10. Tears contain
all of the above
Score =
Correct answers:
Read More

Books to refer for GATE Biotechnology Exam Syllabus wise

Engineering Mathematics
  • Linear Algebra: Matrices and determinants, Systems of linear equations, Eigen values and Eigen vectors.
  • Calculus: Limit, continuity and differentiability, Partial derivatives, Maxima and minima, Sequences and series, Test for convergence, Fourier Series.
  • Differential Equations: Linear and nonlinear first order ODEs, higher order ODEs with constant coefficients, Cauchy’s and Euler’s equations, Laplace transforms, PDE- Laplace, heat and wave equations.
  • Probability and Statistics: Mean, median, mode and standard deviation, Random variables, Poisson, normal and binomial distributions, Correlation and regression analysis.
  • Numerical Methods: Solution of linear and nonlinear algebraic equations, Integration of trapezoidal and Simpson’s rule, Single and multistep methods for differential equations.

a) Microbiology: Prokaryotic and eukaryotic cell structure; Microbial nutrition, growth and control; Microbial metabolism (aerobic and anaerobic respiration, photosynthesis); Nitrogen fixation; Chemical basis of mutations and mutagens; Microbial genetics (plasmids, transformation, transduction, conjugation); Microbial diversity and characteristic features; Viruses.
Books to refer: 
b)Biochemistry: Biomolecules and their conformation; Weak inter-molecular interactions in bio macromolecules; Chemical and functional nature of enzymes; Kinetics of single substrate and bi-substrate enzyme catalyzed reactions; Bioenergetics; Metabolism (Glycolysis, TCA and Oxidative phosphorylation); Membrane transport and pumps; Cell cycle and cell growth control; Cell signaling and signal transduction.
Books to refer: 
c) Molecular Biology and Genetics: Molecular structure of genes and chromosomes; DNA replication and control; Transcription and its control; Translational processes; Regulatory controls in prokaryotes and eukaryotes; Mendelian inheritance; Gene interaction; Complementation; Linkage, recombination and chromosome mapping; Extrachromosomal inheritance; Chromosomal variation; Population genetics; Transposable elements, Molecular basis of genetic diseases and applications.Complementation; Linkage, recombination and chromosome mapping; Extrachromosomal inheritance; Chromosomal variation; Population genetics; Transposable elements, Molecular basis of genetic diseases and applications.
Books to refer: 
d) Process Biotechnology: Bioprocess technology for the production of cell biomass and primary/secondary metabolites, such as baker’s yeast, ethanol, citric acid, amino acids, exo-polysacharides, antibiotics and pigments etc.; Microbial production, purification and bioprocess application(s) of industrial enzymes; Production and purification of recombinant proteins on a large scale; Chromatographic and membrane based bioseparation methods; Immobilization of enzymes and cells and their application for bioconversion processes. Aerobic and anaerobic biological processes for stabilization of solid / liquid wastes; Bioremediation.
Books to refer: 

e) Bioprocess Engineering: Kinetics of microbial growth, substrate utilization and product formation; Simple structured models; Sterilization of air and media; Batch, fed-batch and continuous processes; Aeration and agitation; Mass transfer in bioreactors; Rheology of fermentation fluids; Scale-up concepts; Design of fermentation media; Various types of microbial and enzyme reactors; Instrumentation in bioreactors.
f) Plant and Animal Biotechnology: Special features and organization of plant cells; Totipotency; Regeneration of plants; Plant products of industrial importance; Biochemistry of major metabolic pathways and products; Autotrophic and heterotrophic growth; Plant growth regulators and elicitors; Cell suspension culture development: methodology, kinetics of growth and production formation, nutrient optimization; Production of secondary metabolites by plant suspension cultures; Hairy root cultures and their cultivation. Techniques in raising transgencies.
g) Characteristics of animal cells: Metabolism, regulation and nutritional requirements for mass cultivation of animal cell cultures; Kinetics of cell growth and product formation and effect of shear force; Product and substrate transport; Micro & macro-carrier culture; Hybridoma technology; Live stock improvement; Cloning in animals; Genetic engineering in animal cell culture; Animal cell preservation.
Books to refer: 

h)Immunology: The origin of immunology; Inherent immunity; Humoral and cell mediated immunity; Primary and secondary lymphoid organ; Antigen; B and T cells and Macrophages; Major histocompatibility complex (MHC); Antigen processing and presentation; Synthesis of antibody and secretion; Molecular basis of antibody diversity; Polyclonal and monoclonal antibody; Complement; Antigen-antibody reaction; Regulation of immune response; Immune tolerance; Hyper sensitivity; Autoimmunity; Graft versus host reaction.
Books to refer: 
i) Recombinant DNA Technology: Restriction and modification enzymes; Vectors: plasmid, bacteriophage and other viral vectors, cosmids, Ti plasmid, yeast artificial chromosome; cDNA and genomic DNA library; Gene isolation; Gene cloning; Expression of cloned gene; Transposons and gene targeting; DNA labeling; DNA sequencing; Polymerase chain reactions; DNA fingerprinting; Southern and northern blotting; In-situ hybridization; RAPD; RFLP; Site-directed mutagenesis; Gene transfer technologies; Gene therapy.
Books to refer: 
j)Bioinformatics: Major bioinformatics resources (NCBI, EBI, ExPASy); Sequence and structure databases; Sequence analysis (biomolecular sequence file formats, scoring matrices, sequence alignment, phylogeny); Genomics and Proteomics (Large scale genome sequencing strategies; Comparative genomics; Understanding DNA microarrays and protein arrays); Molecular modeling and simulations (basic concepts including concept of force fields).
Books to refer:
Read More

GATE Biotechnology /Life Sciences 2015 - Notification, Important Dates

Graduate Aptitude Test in Engineering (GATE) is an all India examination that primarily tests the comprehensive understanding of the candidate in various undergraduate subjects in Engineering/Technology/Architecture and post-graduate level subjects in Science. The GATE score of a candidate reflects a relative performance level in a particular subject in the exam across several years. The score is used for admissions to post-graduate programs (e.g., M.E., M.Tech, direct Ph.D.) in Indian institutes of higher education with financial assistance provided by MHRD and other Government agencies. The score may also be used by Public and Private Sector Undertakings for employment screening purposes.
GATE exam
Exam mode: Examinations for all the 22 papers will be conducted by an ONLINE Computer Based Test (CBT). The online examination paper will contain some questions for which numerical answers must be keyed in by the candidate using the virtual keypad. Rest of the questions shall be of Multiple Choice Question (MCQ) type.
Important Dates:

Application Process: For GATE 2015 all information related to the candidateswill be available in a single GATE Online Application Processing System (GOAPS). Candidates have to register and fill the application via ONLINE mode ONLY by accessing the zonal GATE websites of IISc and any of the seven IITs. The photograph
and signature of the applicant must be uploaded during the online application.Please note that all necessary certificates, such as, degree certificate/certificate from the Principal and the category certificate, if any are also to be uploaded. Please note that application forms are not available for sale anywhere else.
GATE Paper code
XL (Life Sciences)Paper A candidate appearing in the XL paper has to answer the following
1. Section H – Chemistry
2. GA – General Aptitude
3. Any two of XL sections I to M
The choice of two sections from I to M can be made during the examination after
viewing the questions. Only two optional sections can be answered at a time. A candidate wishing to change midway of the examination to another optional section must first choose to deselect one of the previously chosen optional sections (I to M).
Duration and Examination Type: The GATE examination consists of a single paper of 3-hour duration that contains 65 questions carrying a maximum of 100 marks. The question paper will consist of both multiple choice questions (MCQ) and numerical answer type questions.
How to apply:  All candidates have to apply only ONLINE. Details of the application fee are shown in
Table. The application fee is non-refundable.
Official Brochure: GATE Notification 2015 
Read More

CSIR UGC NET JRF Life Sciences Part B (June 2014)

11. During protein synthesis in prokaryotes, the peptidyl transferase activity required for peptide bond formation is due to
a) ribosomal protein
b) aminoacyl tRNA
c) 16S ribosomal RNA
d) 23S ribosomal RNA

12. The distance between bacterial genes as determined from interrupted mating experiments are measured in units of

13. Branchiostomaisa
a) deuterostome and schizocoelomate
b) protostome abd schizocoelomate
c) deuterostome and enterocoelomate
d) protostome and anterocoelomate

14. The most important reproductive strategies of big trees in a forest are
a) Earlier age at first reproduction and production of large number of small seeds
b) Earlier age at first reproduction and production of a small number of large seeds
c) Later age at first reproduction and production of a large number of small seeds
d) Later age at first reproduction and production of a small number of large seeds

15. Which one of the following is unfavorable for protein folding?
a)conformational entropy
b) Hydrogen bonding
c) Vander Waals interaction
d)hydrophobic interaction

16. The organs ‘radula’ and ‘citellum’ are found in
a) Mollusca and Annelida, respectively
b) Annelida and Mollusca , respectively
c)Coelenterata and Echinodermata, respectively
d) Echinodermata and Coelenterata, respectively

17.The peptide unit (-CO-NH-) is planar due to
a) Restriction around C-C bond
b) Restriction around C-N bond
c) Restriction around N-C bond
d) Hydrogen bonding between carbonyl oxygen and imino hydrogen of the peptide backbone.

18. Molecules primarily responsible for the formation of lipid raft are
Space-filling models of sphingomyelin (a) and cholesterol (b).

a) sphingolipids and cholesterol
b) phosphatidyl inositol and cholesterol
c) glycosylphosphatidyl inositol and chloesterol
d) phosphatidyl serine and phosphatidyl serine

19. Membrane bound and free ribosomes, are structurally identical, but differ only at a given time in terms of association with
a) Phospholipids
b) nascent proteins
c) glycosylated proteins
d) acetylated proteins

20. A pathogen like mycobacterium, which colonizes inside the cells of the host, is likely to be least affected by which one of the following host immune defence mechanisms?
a) Cytokines
b) cell mediated immune response
c) cd+4 T lymphocytes
d)Humoral immnune response
Learn more:
11. d) 23S ribosomal RNA
12. c)minutes
13. c) deuterostome and enterocoelomate
14. d) Later age at first reproduction and production of a small number of large seeds
15. a)conformational entropy
16. a) Mollusca and Annelida, respectively
17. b) Restriction around C-N bond
18. a) sphingolipids and cholesterol
Lipid rafts generally contain 3 to 5-fold the amount of cholesterol found in the surrounding bilayer. Also, lipid rafts are enriched in sphingolipids such as sphingomyelin, which is typically elevated by 50% compared to the plasma membrane.
19. b) nascent proteins
20. d)Humoral immnune response
Read More

© Biology Exams 4 U, AllRightsReserved.***Best viewed in Google Chrome and Mozilla firefox***

Maintained by