Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 54824
TLS Online TPP Program

#Question id: 799

The two cleavage reactions required to generate the miRNA from these primary transcripts are mediated by two distinct RNases. A characteristic of both these enzymes is that they recognize and cleave RNAs on the basis of the structure of their substrates rather than their specific sequence. Which of the following statement is INCORRECT regarding the cleavage reactions that produces a mature RNA?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. Drosha resides in the cell’s nucleus, and the Drosha-catalyzed cleavage event occurs in that cellular compartment that generates a pre-miRNA which is ~65–70 nucleotides long.

  2. The pre-miRNA liberated by Drosha is exported to the cytoplasm, where the second RNA cleavage reaction, performed by Dicer, takes place which cleaves pre-miRNA 22 nucleotides from its ends.

  3. For processing by Drosha, ssRNA lacking significant secondary structure, is needed flanking each side (5’ and 3’) of the stem-loop. It is the ssRNA–dsRNA junctions that are in responsible for determining the cleavage specificity of Drosha.

  4. The RNase II family enzymes are specific for dsRNA and cleave it in a manner that leaves a 2-nucleotide overhang on the 3’ ends of the dsRNA product. This 3’ overhang is important for recognition of that RNA molecule by the next enzyme in the pathway, Dicer.

More Questions
TLS Online TPP Program

#Question id: 10226

#Unit 6. System Physiology – Plant

Under moderate excess light Quantum efficiency decreases , but the maximum photosynthetic rate remains unchanged and caused by the diversion of absorbed light energy toward heat dissipation—hence the decrease in quantum efficiency this term is known as
TLS Online TPP Program

#Question id: 10223

#Unit 6. System Physiology – Plant

when plastoquinone is accumulates in the reduced state, Reduced plastoquinone accumulates when PSII is being activated more frequently than PSI. What will happen when plastoquinone becomes more oxidized?
TLS Online TPP Program

#Question id: 10222

#Unit 6. System Physiology – Plant

Energy partitioning between two photosystem protects them from quick dessipation or quick inactivation this energy partitioning take place by a protein kinase that can phosphorylate a specific threonine residue on the surface of LHCII, what is the role of LHCII in phosphorylated and non-phosphorylated state?

a.) LHCII in phosphorylated state migrate towards the PSI in the unstacked region and delivers energy to the PSI 

b.) LHCII in nonphosphorylated state moves back to the grana and delivers energy to the PSII

c.) LHCII in phosphorylated state migrate towards the PSII in the stacked region and delivers energy to the PSI 

d.)  LHCII in nonphosphorylated state moves towards the stroma lamellae unstacked region and delivers energy to the PSII 

Which of the following combination is CORRECT?
TLS Online TPP Program

#Question id: 10220

#Unit 6. System Physiology – Plant

Thylakoid membranes contain a protein kinase that can phosphorylate a specific threonine residue on the surface of LHCII. How the kinase is activated?
TLS Online TPP Program

#Question id: 10219

#Unit 6. System Physiology – Plant

The PSII reaction center leads to easily  inactivation and damage by photoinhibition process while Photosystem I Is Protected from Active Oxygen Species, Why PSI protect from active oxygen species in compare to PSII
TLS Online TPP Program

#Question id: 10217

#Unit 6. System Physiology – Plant

Another effect that appears to be a major factor in the stability of the photosynthetic apparatus, which occurs when excess excitation arriving at the PSII reaction center leads to its inactivation and damage is known as