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#Question id: 1993


When antibodies attack antigens, clumping of the affected cells generally occurs. This is best explained by

#Unit 4. Cell Communication and Cell Signaling
  1. the shape of the antibody with at least two binding regions.

  2. disulfide bridges between the antigens.

  3. complement that makes the affected cells sticky.

  4. bonds between class I and class II MHC molecules.

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TLS Online TPP Program

#Question id: 28981

#Unit 7. System Physiology – Animal

Phenylketonuria (PKU) is caused by___
I-Mutation of the gene for phenylalanine hydroxylase
II-tetrahydrobiopterin (BH4) deficiency
III-mutation in dihydroxyphenylalanine 
IV-due to the substitution mutation in tetrahydrobiopterin

TLS Online TPP Program

#Question id: 11619

#Unit 8. Inheritance Biology

If a cross between restricted and dusky  ducks  the only progeny will be form from this cross is restricted and mallard, so what will be the genotype of parents?

TLS Online TPP Program

#Question id: 10284

#Unit 6. System Physiology – Plant

Allosteric regulation of enzyme multisubunit or multiactive site shows cooperativity with the sigmoidal graph between substerate conc. v/s Activity,


a) Cell contain NADH, FADH2 and ATP, that inhibits the allosteric enzyme activity by lowering the affinity with its substate, graph shifts towards B from control

 b) A- shows low ATP, the Km for fructose 6-phosphate is relatively low, the affinity of the enzyme with its substate is relatively high

 c) Haemoglobin, Phosphofructokinase, Phosphate dehydrogenase complex, α-ketoglutarate dehydrogenase complex, these all enzymes shows characteristics of sigmoidal graph

 d) When ATP is high, Km for fructose 6-phosphate is greatly increased- this activity shown by B in the graph

 e) fructose 2,6-bisphosphate binds to its allosteric site on PFK-1, it increases the enzyme’s affinity for its substrate fructose 6-phosphate and reduces its affinity for the allosteric inhibitors ATP and citrate- shown in graph by A

 Which of the following  combination of the enzyme activity with its substate correctly shown;

TLS Online TPP Program

#Question id: 4313

#Unit 3. Fundamental Processes

Which of the following statements best describes the characteristics of siRNA?

TLS Online TPP Program

#Question id: 3683

#Unit 3. Fundamental Processes

In some viruses, RNA serves as the storage of genetic materials and DNA is synthesized from RNA by the enzyme known as: