Biotechnology Eligibility Test Preparation

DBT BET Previous Year Question Paper: 2012-2013 with Answer key: Part 4 (Question 101 – 150)


Telomer-structure

Three-dimensional structure of a telomere G-quadruplex (source wikipeida)

Biotechnology Eligibility Test (BET) for DBT JRF Award (2012-13)
Previous Year Question Papers with Answer Key, Explanations & References
Government of India, Ministry of Science & Technology
Department of Biotechnology, New Delhi
PART: B Set 4 (Questions 101– 150)


101. Telomeres consists of simple sequence repeats of

a. CATT rich strands that interact with protein
b. GCCT rich strands that interact with protein
c. CTTT rich strands that interact with protein
d. TTAGGG rich strands that interact with protein

Ans. (a)

Telomere is the sequence occurs at the end of chromosome. Telomere helps to maintain the integrity of chromosome by preventing the end to end fusion of different chromosome and deterioration of chromosomes by nucleases. In vertebrates telomere consists of TTAGGG sequence repeats (~2500 repeats).

102. True activators of transcription are transcription factors that binds to

a. Other proteins to enhance transcription
b. Promoters
c. Enhancers
d. Promoters and enhancers

Ans. (c)

Enhancers are cis acting transcription factor binding sites of DNA (50 – 1500 bp long) of specific genes

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Biotechnology Eligibility Test Preparation

DBT BET Previous Year Question Paper: 2012-2013 with Answer Key: Part 3 (Questions 51-100)


PLoSBiol3.5.Fig7ChromosomesAluFish

Alu sequence in Human Chromosomes (green fluorescence) Source Wikipedia

Biotechnology Eligibility Test (BET) for DBT JRF Award (2012-13)
Previous Year Question Papers with Answer Key, Explanations & References
Government of India, Ministry of Science & Technology
Department of Biotechnology, New Delhi

 PART: B Set 3 (Questions 51 – 100)


51. Suppressor tRNA mutations are those in which

a.       Transcription of tRNA genes is suppressed
b.      Translation form mRNA is suppressed due to absence of tRNA
c.       Amino acid is incorporated in place of a stop codon due to mutation in anticodon region of tRNA
d.      Charging of tRNA with cognate amino acids is suppressed due to mutation in amino acyl tRNA synthase enzyme

Ans. (c)

Suppressor tRNA: also called as nonsense suppressor, due to the suppressor tRNA mutations, an amino acid is incorporated into the stop codon due to mutation in the anticodons of tRNA so that the releasing factors of translation cannot binds to the complex and the translocation process continues.

52. Which of the following media is best suited for the selective growth of E. coli with genotype: Str+ His- leu- lys-?

a.       Minimal medium with thiamine, histidine, leucine and lysine
b.      Luria agar
c.       Minimal medium with thiamine and streptomycin
d.      Minimal medium with thiamine, histidine, leucine, lysine and streptomycin

Ans. (d)

Minimal medium: media that contains minimum nutrients possible for bacterial growth, usually without the presence of amino acids. They used by microbiologists and geneticists to grow “wild type” microorganisms and to select microbes against recombinants.

In the question, the given bacterium is mutated for Histidine, Leucine, and lysine and it has got an antibiotic resistant gene Str+.

53. Which of the following amino acid is coded by maximum number of codons?

a.       Leucine
b.      Tryptophan
c.       Valine
d.      Alanine

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Ecology Lecture Notes

Major Threats to Biodiversity by Human Activities (Simple, Easy Ecology Lecture Notes)


Causes of biodiversity loss degradation

‘It is that range of biodiversity that we must care for – the whole thing –
rather than just one or two stars’

David Attenborough


What are major threats to biodiversity?

Major threats to biodiversity are:

1.  Habitat destruction/Deforestation

2.  Introduced and invasive species

3.  Genetic pollution

4.   Over exploitation

5.   Hybridization

6.   Climate change

7.   Diseases

8.   Human over-population

(1). Habitat destruction/Deforestation:

Ø  Habitat destruction and deforestation has played a key role in extinction

Ø  Habitat loss occurs when natural habitats are modified for human needs

Ø  Factors causing habitat destruction are: Over-population, Deforestation, Pollution and Global warming

Ø  Habitat size and number of species are systematically related

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Ecology Lecture Notes

Biodiversity: Introduction (Definition, Classification, Importance and Measurement of Biodiversity)


What is biodiversity?

Look deep into nature, and then you will understand everything better’
Albert Einstein


What is biodiversity?

@. Biodiversity- definition: “variability among living organisms”

@. Biodiversity is the variety and variability of genus, species and ecosystem between and within

@. It is the number of different organisms & their relative frequency in an ecosystem

@. The term Biodiversity is coined by Walter Rosen, 1985

@. About 50 million sps. of plants, animals & microbes are existing in the world

@. Among this only 2 million are identified so far

@. Biodiversity also includes: Variability of genus, Variability of varieties, Variability of species, Variability of populations in different ecosystems, Variability in relative abundance of species

@. Knowledge of biodiversity is essential for sustainable utilization of resources

@. Biological resources provide us: Nourishment, Clothing, House, Fuel, Medicine and Revenue

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Ecology Lecture Notes

Why Biodiversity is Rich in Tropics?


World map indicating tropics and subtropics

Tropical Area Highlighted in Pink (source wikipedia)

Tropical Area

Ø  Tropical region is the part of earth surrounding the equator

Ø  Exactly it cover the region between tropic of cancer and tropic of capricorn

Tropic of Cancer: 23.43º towards Northern Hemisphere

Tropic of Capricorn: 23.43° towards Southern Hemisphere

Ø  Tropical regions receive maximum sunlight over the year

Ø  Tropical vegetation are the most productive vegetation on earth

Ø  Tropical areas are rich in biodiversity

Ø  Majority of the endemic species of earth belongs to tropical areas

Ø  Majority of the Mega-biodiversity Centers and Mega-biodiversity hotspots are in the tropics

Ø  In bio-geography, tropical area are divided into:

(1). Paleotropics: Africa, Asia and Australia

(2). Neotropics: Caribbean, Central America and South America

Why biodiversity is rich in tropics?

Tropical areas are rich in biodiversity than temperate regions, because:

@.  Warm temperature and high humidity of tropical region are favourable for most of the species on earth

@.  Tropical areas have more stable climate than temperate regions

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