Free Net Life Science Study Materials

NET XL December 2015 Question Paper with Answer Key (Part II)

Life Sciences NET Dec 2015

Previous Year Question Papers of CSIR – UGC /JRF/NET: Life Science Examination, December 2015 (II)
(Original Question Paper with Answer Key, Explanations and References)

PART: B (Questions 41 – 60)

(41). Phenylalanine, a precursor of most of the phenolics in higher plants is a product of which one of the following pathways?

a.       Shikimic acid pathway
b.      Malonic acid pathway
c.       Mevalonic acid pathway
d.      Methylerythritol pathway

Ans. (a)

Shikimic acid pathway is a metabolic seven step pathway in bacterial, fungi, and plants for the synthesis of aromatic amino acids such as Phenylalanine, tyrosine and tryptophan. Shikimic acid pathway is completely absent in animals and hence all the above amino acids are essential amino acids to animals

Mevalonic acid pathway is for the production of  isoprenoids.

(42). For which one of the following physiological studies 12CO2 and 13CO2 are used?

a.       Estimate the rate of photosynthesis
b.      Determine rate of photorespiration
c.       The ratio of C4 and CAM pathways of CO2 fixation
d.      The ratio of C3 and C4 pathways of CO2 fixation

Ans. (d)

(43). Gibberellic acid (GA) controls seed germination by directing breakdown of the stored starch. In which one of the following tissues of the barley seed, – amylase gene is induced in response to GA?

a.       Endosperm
b.      Coleoptile
c.       Aleurone layer
d.      Embryo

Ans. (c)

During seed germination, plant embryo produces gibberellin which triggers the aleurone cells to release α-amylase for the hydrolysis of starch stored in the endosperm.

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Job opportunities in biology life sciences

Scientist Job Vacancy at MoEF and ZSI (32 Posts, Direct Recruitment)

ZOI Scientist Job

Government of India
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Job Vacancy at MoEF

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Molecular Biology Tutorials

Cell Cycle Checkpoints in Regulation of Cell Division and Cancer

Cell Cycle Checkpoints and Cancer

Cell Cycle Checkpoints and Regulation of Cell Cycle

What is cell cycle checkpoint?

Every cell in our body pass through a series of different stages in a cyclic manner called cell cycle.  Cell cycle is a sequential step that taking place in a cell leading to the accurate duplication of genetic materials (DNA), precise separation of replicated genetic materials and passing them in to two daughter cells.  The process of cell cycle is very critical in each cell, thus it operate strictly under strong surveillance to prevent any mistakes. This strong surveillance system in the cell to monitor the cell cycle progression itself is called cell cycle checkpoints.

Checkpoints are surveillance mechanisms that halt the progress of cell cycle if (1) any of the chromosomal DNA is damaged, or (2) critical cellular processes, such as DNA replication during S phase or chromosome alignment during M phase, have not been properly completed. Thus cell cycle checkpoints ensure that the various events in the cell cycle progression occur accurately and in correct order. In this post we will discuss the three types of cell cycle checkpoints that operate in eukaryotic cells during cell cycle progression.

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Free Net Life Science Study Materials

CSIR NET Life Sciences December 2015 Question Paper with Answer Key (Part-1)

NET December 2015 Answer Key

Previous Year Question Papers of CSIR – UGC /JRF/NET: Life Science Examination, December 2015 (II)
(Original Question Paper with Answer Key, Explanations and References)

PART: B (Questions 21 – 40)

(21). The ionic strength of a 0.2 M Na2HPO4 solution will be:

a.       0.2 M
b.      0.3 M
c.       0.6 M
d.      0.8 M

Ans. (c)

Ionic strength of a solution is the function of all ions present in a solution.

(22). A cell line deficient in salvage pathway for nucleotide biosynthesis was fed with medium containing 15N labelled amino acids. Purines were then extracted. Treatment with which one of the following amino acids is likely to produce 15N labelled purines?

a.       Aspartic acid
b.      Glycine
c.       Glutamine
d.      Aspartamine

Ans. (c)

(23). Enzymes accelerate a reaction by which one of the following strategies?

a.       Decreasing energy required to form the transition state.
b.      Increasing kinetic energy of the substrate.
c.       Increasing the free energy difference between substrate and the product.
d.      Increasing the turn over number of enzymes.

Ans. (a)

Transition state is the state of substrate with highest energy; they are least stable than products and other substrate molecules. They have the highest energy along the reaction coordinate and they have the highest free energy. Enzymes accelerate the chemical reactions by lowering the energy required to reach the transition state of a substrate.

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Botany lecture notes

Enzymes in Plant Pathogenesis (Host Parasite Interactions-Part I)

Host Parasite Interactions

(Plant-Pathogen Interaction Part I: Enzymes in Plant Pathology)

What are the enzymes involved in pathogenesis (plant pathology)?

Most of the fungal and bacterial parasites produce many enzymes that degrade the plant materials in vivo. Enzymes involved in pathogenesis or virulence (process of disease initiation) includes both constitutive and inducible enzymes.

(1). Constitutive enzymes are those enzymes which are present all the time in the cells.

(2). Inducible enzymes are those enzymes which are produced only when they are needed by the cells in response to certain internal or external stimuli.

Important classes of enzymes involved in pathogenesis are:

(1). Cutinases

(2). Pectinases

(3). Cellulases

(4). Hemicellulases

(5). Ligninases

(6). Lipases

(7). Proteinases

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