GATE Biotechnology (BT) 2015 Original Question Paper with Answerkey and Explanations (Part I)

GATE Biotechnology (BT) 2015
(Graduate Aptitude Test in Engineering: Original Question Paper)
Original Question Paper (Part 1: Question 1 – 20)

(1). Which one of the following complement proteins is the initiator of the membrane attack complex?

a. C3a
b. C3b
c. C5a
d. C5b

(2). Levinthal’s paradox is related to

a. Protein secretion
b. Protein degradation
c. Protein folding
d. Protein trafficking

(3). Which one of the following is a second generation genetically engineered crop?

a. Bt brinjal
b. Roundup soyabean
c. Golden rice
d. Bt rice

(4). Based on the heavy chain, which one of the following antibodies has multiple subtypes?

a. IgM
b. IgD
c. IgE
d. IgG

(5). The cytokinesis organelle in plant cells is______.

a. Centriole
b. Phragmoplast
c. Proplastid
d. Chromoplastid

(6). Anergy refers to:

a. Mitochondrial dysfunction
b. Allergy to environmental antigens
c. Unresponsiveness to antigens
d. A state of no energy

(7). ABO blood group antigens in human are differentiated from each other on the basis of:

a. Sialic acid
b. Lipids
c. Spectrin
d. Glycoproteins

(8). Which of the following organisms is used for the determination of phenol co-efficient of a disinfectant?

a. Salmonella typhi
b. Escherichia coli
c. Candida albicans
d. Bacillus psychrophilus

(9). A single subunit enzyme converts 420 µmoles of substrate to product in one minute. The activity of the enzyme is ______ X 10-6 Katal.

a. 5
b. 6
c. 7
d. 8

10. Which of the following amino acids has the highest probability to be found on the surface of a typical globular protein in aqueous environment?

a. Ala
b. Val
c. Arg
d. Ille

(11). Which one of the following is NOT a product of de-nitrification in Pseudomonas?

a. N2
b. N2O
c. NO2
d. NH4+

(12). Which of the following feature is NOT required in a prokaryotic expression vector?

a. OriC
b. Selection marker
c. CMV promoter
d. Ribosome binding site

(13). Production of monoclonal antibodies by hybridoma technology requires:

a. Splenocytes
b. Osteocytes
c. Hepatocytes
d. Thymocytes

(14). Which of the following is INCORRECT about a typical apoptotic cell?

a. Phosphatidylserine is presented on the outer cell surface
b. Cytochrome c is released from mitochondria
c. Mitochondrial membrane potential does not change
d. Annexin-V binds to the cell surface

(15). Identify the file format given below

ProteinX – Homo sapiens

a. GDE
d. GCG

(16). Which one of the following relations holds true for the specific growth rate (µ) of a microorganism in the death phase?

a. µ = 0
b. µ < 0
c. µ = µmax
d. 0 < µ < µmax

(17). How many 3-tuples are possible for the following amino acid sequence? (MADCMWDISEASE)

a. 4
b. 5
c. 11
d. 12

(18). How many different protein sequences of 100 residues can be generated using 20 standard amino acids?

a. 10020
b. 100 X 20
c. 20100
d. 100! X 20!

(19). In DNA sequencing reactions using the chain termination method, the ratio of ddNTPs to dNTPs should be

a. 0
b. < 1
c. 1
d. > 1

(20). Which of the following graph represent un-competitive inhibition?

2015 gate biotechnology

a. Graph A
b. Graph B
c. Graph C
d. Graph D

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Answer Key and Explanations:

1. Ans. (d). C5b
Membrane attack complex (MAC) or terminal complement complex (TCC) is a complex structure formed on the pathogenic bacteria due to the activation of host complement system. MAC forms trans-membrane channels which disrupt the phospholipid bilayer of target cells leads to cell lysis and death. MAC composed of four complement proteins (C5b, C6, C7 and C8)

2. Ans. (c). Protein folding
Levinthal’s paradox: Describes the possible number of different folding pattern by a single polypeptide chain. Since free rotation is possible between bonds in the polypeptide chain a single polypeptide with 10 amino acids will have 9 peptide bonds and thus they will have 18 phi and psi bond angles with ‘n’ number of rotational possibilities. Thus this protein may have an astronomical number of possible conformations. If this is true, the protein will take longer time periods to attain its correct conformation which may be approximately millions of years. This is not the real situation. This paradox is traditionally called as Levinthal’s paraxon, since Cyrus Levinthals for the first time (in 1969) mentioned it.

3. Ans. (c). Golden rice
Bt. Brinjal: A genetically modified brinjal with crystal protein gene (Cry1Ac) from Bacillus thuringiensis to create resistance against Lepidopteron insects.
Roundup soyabean: Genetically modified soybean with glyphosate resistance. Glyphosate (also called as roundup, produced by Monsanto) is a broad spectrum synthetic herbicide. Glyphosate kill the plant by interfering with the synthesis of aromatic amino acids such as phenylalanine, tyrosine and tryptophan.
Golden rice: Genetically modified rice with gene for the biosynthesis of beta carotene, a precursor of vitamin A, in the edible part of the rice. Golden rice was produced by Ingo Potrykus and Peter Beyer

4. Ans. (d). IgG

5. Ans. (b). Phragmoplast
Phragmoplast: A complex structure formed during the cytokinesis of plant cells. Due to presence of cell wall in plant cells, the usual furrowing and cleavage method of cytokinesis is not possible in plant cells. In plants the process of cytokinesis is accomplished by the formation of cell plate. Phragmoplast serves as the scaffold for the cell plant assembly and the subsequent formation of new cell wall between the two daughter cells. Phragmoplast is a complex assembly of microtubules, microfilaments and remnants of endoplasmic reticulum at the mitotic metaphase plane.

6. Ans. (c). Unresponsiveness to antigens

7. Ans. (d). Glycoproteins

8. Ans. (a). Salmonella typhi

Phenol co-efficient: a measure of bactericidal activity of a chemical compound in relation to phenol. It denote the disinfecting power of a chemical

9. Ans. (c). 7

10. Ans. (c). Arg
The exterior portion of globular protein will have polar amino acids, whereas the interior portion has non polar amino acids. In the options, Ala, Val and Ile are non-polar amino acids.

11. Ans. (d). NH4+

12. Ans. (c). CMV Promoter

Cytomegalovirus (CMV promoter) and SV40 promoter are usually used in mammalian expression vectors
In bacterial expression vector (prokaryotic) lac operon promoter or bacteriophate T7 promoter are used

13. Ans. (a). Splenocytes
Splenocyte: any type of white blood cells (WBC) situated in the spleen tissue. It contains a variety of cell population such as T, B cells, dendritic cells, macrophages etc.

Hybridoma technology: a technology for the production of monoclonal antibodies by fusing an antibody producing cells (B cells) to cancerous B cells (myeloma) so that these hybrids cells can be grown for many generations in the culture medium to have a continuous supply of monoclonal antibodies. Hybridoma technology was invented by Cesar Milstein and Georges J. F. Kohler in 1975.

14. Ans. (c). Mitochondrial membrane potential does not change
In a typical apoptotic cells the mitochondrial membrane potential changes

15. Ans. (c). NBRF

16. Ans. (b). µ < 0

17. Ans. (c). 11

18. Ans. (c). 20 100

19. Ans. (b). < 1
The concentration of ddNTPs in the medium should be minimum

20. Ans. (a). Graph A
With uncompetitive inhibitor, the Vmax and Km changes by the factor of inhibitor concentration

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