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TLS Online TPP Program

#Question id: 13161

Which of the following mechanism depends on the activation of heterotrimeric G proteins?

#Unit 4. Cell Communication and Cell Signaling
  1. During actin filament formation, the inactive formin is activated when its Rho-binding domain (RBD) binds to membrane-bound active Rho-GTP, resulting in exposure of the formin’s FH2 domain, which can then nucleate the assembly of a new actin filament.
  2. Rod cells sense light with the aid of a light-sensitive rhodopsin which is coupled to transducin. On absorption of a photon, the retinal moiety of rhodopsin is immediately converted from the cis isomeric form to the all-trans isomeric form, causing a conformational change that allows rhodopsin to bind the α subunit of transducin.
  3. Ras proteins are “switch” proteins and not directly linked to cell-surface receptors. Ras activation is accelerated by a guanine nucleotide exchange factor (GEF), which binds to the Ras∙GDP complex, causing dissociation of the bound GDP.
  4. During the regulation of microfilament organization, Cdc42 act as molecular switches, inactive in the GDP-bound state and active in the GTP-bound state.
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TLS Online TPP Program

#Question id: 10224

#Unit 6. System Physiology – Plant

Exposure to high levels of excess light that damage the photosynthetic system and decrease both quantum efficiency and maximum photosynthetic rate results
TLS Online TPP Program

#Question id: 10225

#Unit 6. System Physiology – Plant

Air circulation around the leaf removes heat from the leaf surfaces if the temperature of the leaf is higher than that of the air; this phenomenon is called
TLS Online TPP Program

#Question id: 10250

#Unit 6. System Physiology – Plant

Glycolysis involves a series of reactions catalyzed by enzymes located in,
TLS Online TPP Program

#Question id: 10196

#Unit 6. System Physiology – Plant

Why are light compensation points lower for shade plants?
TLS Online TPP Program

#Question id: 10228

#Unit 6. System Physiology – Plant

Photorespiration and the quantum yield differ between C3 and C4 photosynthesis, with changes particularly noticeable as temperatures vary quantum yield for photosynthesis as a function of leaf temperature in C3 plants and C4 plants. Following are some statements  based on this study.

 a.) In the C4 plants the quantum yield remains constant with temperature, reflecting low rates of photorespiration

 b.) At lower temperatures the quantum yield of C3 plants is higher than that of C4 plants

c.) C3 photosynthesis is more efficient at lower temperatures

 d.) At higher temperatures the quantum yield of C3 plants is higher  than that of C4 plants

 Which one of the following combination of above statements is correct?
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