Biology Exams 4 U

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Worksheet on Bacteriophage

Bacteriophages are  viruses that attacks bacteria. This is a simplified worksheet that helps you to understand the structure of a bacteriophage. The same is given as interactive online quiz also. Enjoy learning bio... 
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ICAR Notification ARS 2016 and NET 2017

The Agricultural Scientists Recruitment Board (ASRB) will hold a combined ARS- 2016 (Preliminary) and NET (I)-2017 Examination during 16.05.2017 to 21.05.2017 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. (official notification)
The ARS-2016 (Mains) Examination will be conducted on 08.07.2017. Candidates are advised to read the notification carefully before filling the Online Application Form.

For ARS-2016: A candidate must hold a Master’s Degree or equivalent in the concerned discipline with specialization as defined in Appendix-VI, completed on or before 08.07.2017.
Age limit: 
For ARS-2016 A candidate must have attained the age of 21 years but not have attained the age of 32 years as on 01.01.2017. Age relaxation is admissible to the various categories as per Rule 2 of the Rules of the Examination as given in APPENDIX –IV.

For NET (I)-2017 :A candidate must have attained the age of 21 years as on 01.01.2017. There is no upper age limit for the National Eligibility Test.
Number of attempts:
How to apply: A candidate seeking admission to the examination must apply online in the prescribed Application Form available on the website:
Useful Links:
Previous Question Papers Free (ICAR ARS NET Preparation Resources)
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What are Photosystem? Definition and Summary of PS I and PS II

What are Photosystems antenna molecule complex?
The light harvesting complexes (LHC) formed by photosynthetic pigments are located on the thylakoid membrane of the chloroplast in two pigment systems called as Photosystem I and Photosystem II.

Definition: Each photosystem consists of collection of chlorophyll-a molecules, accessory pigments and associated proteins present on the surface of the thylakoid membrane of the chloroplast.
Each photosystems consists of two closely linked components namely reaction centre and antenna molecules.
Photosystems antenna molecule complex
Reaction centre molecules are the primary pigment which is chl-a molecules in green plants. Accessory pigments that surround the reaction centre forms the antenna complex. Accessory pigments include chl-b, carotenes and xanthophylls.

The antenna molecules made up of accessory pigments of photosystems absorb photons (light energy) get excited and transfer the excitation energy to the adjacent accessory pigment and finally reaching the reaction centre by resonance transfer.

Photosystem I (PS I): Reaction centre chl molecule has light absorption peak at 700 nm (P700). PS I occurs mostly on the inter-granal lamellae of the chloroplast. PSI uses light energy to convert NADP+ to NADPH + H+

Photosystem II (PS II): Reaction centre chl molecule has light absorption peak at 680 nm (P680). PS II occurs mostly on the granal lamellae of the chloroplast. PS II uses light energy for photolysis of H2O molecules, or oxidizing H2O molecules producing electrons, protons (H+) and O2.
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3 Major Classes of Photosynthetic Pigments

3 Major classes of photosynthetic pigments in plants
The primary site of photosynthesis is leaf. We have already discussed the exact site of lightdependent and light independent reaction of photosynthesis within the chloroplast in our last post
 An anabolic process by which chloroplast of green plants and other phototrophs synthesize carbohydrates (glucose) and evolve molecular O2 as by-product, using CO2, H2O and sunlight.
  It involves conversion of light energy into chemical energy
 Approx. 0.2 % of light falling on earth is used for photosynthesis
 90% of photosynthesis is in oceans, carried out by fresh water and marine algae
3 Major classes of photosynthetic pigments in plants

3 Major Classes of Photosynthetic pigments in Plants
  • Photosynthetic pigments are located in the thylakoid membranes of the chloroplast. These pigments are capable of converting the energy of sunlight to chemical energy. The pigments absorbs light rays from the visible region of the electromagnetic spectrum
  • The two major groups of pigments are a) Principal Pigments b) Accessory pigments
  • The principal pigment in all photosynthetic plants is chlorophyll-a.
  • Accessory pigments include chlorophyll-b, c, d, carotenoids and phycobilins.
  • In green plants, chlorophyll-a is the primary pigment and chlorophyll-b and carotenoids are the accessory pigments.
1. Chlorophylls:
  • Chlorophylls are magnesium porphyrin derivatives.
  • Chl-a is the primary pigment in photosynthesis and it forms the reaction centre of the photosystems (light harvesting complex, LHC).
  • Chl-b, c, d, e and bacteriochlorophyll are the other type of chlorophyll molecules.
  • Chl absorbs maximum at red and blue region and reflects green light.
  • A chlorophyll molecule consists of a hydrophobic pyrole head and hydrophilic phytol tail with a central Mg atom. The head is formed of 4 pyrole molecules linked together by methane (CH3) group to from a ring called porphyrin ring. The side group of chl-a is methyl group (-CH3) and chl-b is an aldehyde group (-CHO).
  • Chl-a is bluish green and chl b is yellow green.
2. Carotenoids:
  • Carotenoids are fat soluble, accessory pigments with yellow, orange or red colour found in all photosynthetic plants. These pigments absorb blue-violet region of the visible spectrum.
  • Carotenoids are of two groups, carotenes which are red or orange coloured (C40H56) and xanthophylls which are brown or yellow coloured (C40H56O2). The carotenes include α, β, carotene, lycopene, phytoene etc.
  • Xanthophylls include lutein, violaxanthin, zeaxanthin etc.
  • The functions of carotenoids are
  • Absorb more solar energy and transfer it to reaction centre and protects chlorophyll molecules from photo-oxidation
3. Phycobilins:
  • Water-soluble, red or blue accessory pigments present on cyanobacteria and red algae. The structure is similar to chlorophyll molecule but the central Mg is absent.
  • The two types of phycobilins are phycoerythrins which are red coloured and phycocyanins, which are blue coloured.
  • Thus the question how the light energy is converted to chemical energy in photosynthesis? The answer is these pigments can trap the energy of sunlight and the excited electron while moving through different electron acceptors releases some energy which is utilized for the phosphorylation of ADP to ATP. 
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Red Drop and Emerson Enhancement Effect Experiment Summary

Summary Emerson Red Drop and Enhancement Effect

Emerson Red Drop and Enhancement Effect
The rate of photosynthesis is measured as the number of O2 molecules produced per quantum of light absorbed
• Robert Emerson et al (1958): Experimental material Chlorella
Emerson Experimental material Chlorella
• Studying rate of photosynthesis at different wavelengths of light (390-760 nm)
• Monochromatic light of different wavelength is used and rate of photosynthesis is measured
• The sudden fall in photosynthetic yield in the far red region (greater than 680 nm) compared to the red region of the electromagnetic spectrum is called “Emersons red drop”
 The increase in photosynthetic yield by the combined effect of red (680 nm) and far red light (700 nm) is called Emerson enhancement effect or Emerson effect.
 This work provide experimental evidence for the presence of two photo systems-PS I & PS II
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Plant Cell and Animal Cell Diagram Worksheet PDF

This is a worksheet on plant cell and animal cell that helps you to assess your understanding on the structure of both types of cell. Enjoy biology...
Plant Cell and Animal Cell Diagram Worksheet
 Download (PDF)
These are some pages that will help you to improve your concept 

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DBT BET JRF 2016 Section A Questions and Answers

Solved DBT BET JRF previous question papers 2016
11. Statins are very effective against hypercholesterolemia, a major cause of atherosclerosis. These drugs reduce plasma cholesterol levels by
(A) Preventing absorption of cholesterol from the intestine.
(B) Increasing the excretion of cholesterol from the body via conversion to bile acids.
(C) Inhibiting the conversion of 3-hydroxy-3-methylglutaryl-CoA to mevalonate in the pathway for cholesterol biosynthesis.
(D) Increasing the rate of degradation of 3-hydroxy-3-methylglutaryl CoA reductase.

12.  Measles, Mumps, Rubella-MMR combined vaccine represents which one of following vaccine categories?
(A) Inactivated/killed
(B) Live, attenuated
(C) Subunit
(D) Toxoid (inactivated toxin)
13.  A haemophiliac man marries a normal woman. They have a daughter who does  not  show  symptoms  of  haemophilia.  If  she  marries  a  haemophiliac  man, what will be the probability of their son displaying symptoms of haemophilia?
(A) 0%
(B) 25%
(C) 50%
(D) 100%

14.  The  conventional  treatment  for  methanol  toxicity  is  to  administer  ethanol. Which of the following explains the basis of this treatment?
(A)  Ethanol acts as a competitive inhibitor to methanol
(B)  Ethanol acts as a non-competitive inhibitor to methanol
(C)  Ethanol destroys the enzymatic activity of alcohol dehydrogenase
(D)  Ethanol blocks the entry of methanol within the cells.

15.  Electrophoresis  of  a  purified  protein  in  SDS-PAGE  in  the  presence  of  2- mercaptoethanol  yields  two  bands  of  35  kDa  and  45  kDa.  However,  in  a  gel  filtration chromatography, the same protein elutes as 80 kDa. What conclusion  will you draw from the results?  
          (A) The protein is not purified to homogeneity.  
          (B) Two bands generated in SDS-PAGE due to degradation.  
          (C) The protein is a homodimer   
          (D) The protein is a heterodimer
16.  Lysosomes of a cell were labelled with lysotracker Red. Subsequently, these cells were infected with GFP-transfected Mycobacterium and observed under a fluorescence microscope. What will you observe?

(A)  GFP-Mycobacterium will be colocalized with lysotracker Red labeled lysosomes.
(B)  GFP-Mycobacterium  will  be  separated  from  lysotracker  Red  labeled lysosomes.
(C)  GFP-Mycobacterium will not be detected as they are degraded in the cell.
(D)  Lysotracker   Red   labeled   lysosomes   will   be   degraded   in   GFP- Mycobacterium  infected cells

17.  A  linear  DNA  fragment  which  has  3  restriction  sites  for  BamH1,  is  labeled
/only at the 5  end. This DNA is partially digested with BamH1 in such a way that all kinds of fragments are generated. Under these conditions, how many labeled and unlabeled fragments will be produced?
(A) 3 labeled and 4 unlabeled
(B) 3 labeled and 5 unlabeled
(C) 4 labeled and 5 unlabeled
(D) 4 labeled and 6 unlabeled

18. In the preparation of humanized antibody, part of the antibody molecule is taken from mouse and the remaining is taken from that of human, through genetic engineering technique. Which one of the following statements is true for humanized antibody?
(A) CDRs of mouse IgG is fused with framework regions of human IgG
(B) CDRs of human IgG is fused with framework regions of mouse IgG
(C) CDRs of mouse IgG is fused with CDRs of human IgG
(D) framework regions of mouse IgG is fused with  framework regions of
human IgG

19. A 25-year old man undertakes a prolonged fast for religious reasons. Which  one of the following metabolites will be elevated in his blood plasma after 24  hours?  
     (A) Lactic acid  
     (B) Glycogen  
     (C) Ketone bodies  
     (D) Non-esterified fatty acids  
20. Which one of the following is not a deficiency disorder?  
     (A) Beriberi  
     (B) Night Blindness  
     (C) Poliomyelitis  
     (D) Pernicious Anemia  
11. (C) Inhibiting the conversion of 3-hydroxy-3-methylglutaryl-CoA to mevalonate in the pathway for cholesterol biosynthesis.
12. (B) Live, attenuated
13. (C) 50%
14. (A)  Ethanol acts as a competitive inhibitor to methanol
15.  (D) The protein is a heterodimer
16. (A)  GFP-Mycobacterium will be colocalized with lysotracker Red labeled lysosomes.
17. (D) 4 labeled and 6 unlabeled
18. (A) CDRs of mouse IgG is fused with framework regions of human IgG
19. (D) Non-esterified fatty acids  
20.  (C) Poliomyelitis  
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DBT BET JRF Questions And Answers 2016

1. Which one of the following modes of inheritance is seen in Cystic Fibrosis
          (A)  Autosomal recessive  
          (B)  Autosomal dominant 
          (C)  Sex linked 
          (D)  Spontaneous mutation 

2.  Digestion of a 5Kb linear DNA fragment with EcoRI generates two fragments 
of 2 Kb and 3 Kb, while  digestion of the same molecule with HindIII yields three 
fragments of 0.7 Kb, 3.5 Kb and 0.8 Kb. When the same DNA is digested with 
both the enzymes, it yields fragments of 0.7 Kb, 1.3 Kb, 2.2 Kb and 0.8 Kb. The 
right sequence of restriction sites in the DNA fragment is  
       (A)  One EcoRI site in between two HindIII sites 
       (B)  One HindIII site in between two EcoRI sites 
       (C)  Two HindIII sites followed by only one EcoRI site 
       (D)  One EcoRI site followed by two HindIII sites. 
3.  GFP,  when  overexpressed  in  a  cell,  remains mostly  in  the  cytosol.  A  GFP 
construct is modified such that the resultant GFP protein will have a conjugated 
peptide Pro-Lys-Lys-Lys-Arg-Lys-Val at its N-terminus. If such a GFP construct is 
expressed in a cell, the modified GFP protein will be localized in the  
         (A)  lysosome 
         (B)  Golgi bodies 
         (C)  nucleus 
         (D)  endoplasmic reticulum    

4. In a mammalian cell, protein synthesis is regulated at the level of initiation by 
various  kinases.  During  viral  infection,  which  one  of  the  following  kinases  is 
involved  in  regulating  the  step  of  formation  of  eIF2.GTP.Met  tRNA   ternary 
icomplex in the host? 
          (A)  Heme-regulated inhibitor kinase (HRI) 
          (B)  Protein kinase RNA dependent (PKR) 
          (C)  GCN2-like kinase 
          (D)  PKR-like endoplasmic reticulum kinase (PERK) 
5. Which  one  of  the following  side  chains  of  an amino acid  is  responsible for 
fluorescence in proteins? 
          (A)  Indole ring 
          (B)  Guanidino group 
          (C)  Phenolic group 
          (D)  Imidazole group 
6. DNA molecules labeled with 15N and 14N can be separated by 
           (A) Pulse field gel electrophoresis 
           (B) Density gradient ultracentrifugation 
           (C) Capillary electrophoresis 
           (D) Differential centrifugation 
7. Cytoskeletal organization of a cell is regulated by 
          (A)  Ras GTPase 
          (B)  Rab GTPase 
          (C)  Rho GTPase 
          (D)  Ran GTPase 

8.  In  comparison to animals residing in a warm climate, animals living in cold 
climate need thermal insulation.  The  cell  membranes of the latter would have a 
relatively higher content of …… 
            (A)  sphinogolipid 
            (B)  saturated fatty acid 
            (C)  unsaturated fatty acid 
            (D)  cholesterol 
9. In glycolysis, the conversion of 1 mol of fructose 1,6-biphosphate to 2 mol of  
pyruvate results in the formation of 
            (A) 1 mol NAD+ and 2 mol of ATP 
            (B) 2 mol of NAD+ and 4 mol of ATP 
            (C) 2 mol of NADH and 2 mol of ATP 
            (D) 2 mol of NADH and 4 mol of ATP 

10. In diabetic ketoacidosis, increase in which of the following would cause 
elevated production of ketone bodies? 
          (A)  Proteolysis 
          (B)  Urea production 
          (C)  Insulin release 
          (D)  Lipolysis
1. (A)  Autosomal recessive  
2. (A)  One EcoRI site in between two HindIII sites  
3. (C)  nucleus  
4. (B)  Protein kinase RNA dependent (PKR) 
5. (A)  Indole ring  
6. (B) Density gradient ultracentrifugation  
7. (C)  Rho GTPase  
8. (C)  unsaturated fatty acid  
9. (D) 2 mol of NADH and 4 mol of ATP  
10. (D)  Lipolysis
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