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TLS Online TPP Program

#Question id: 12463

Which of the following is primarily responsible for limiting the number of trophic levels in most ecosystems? 

#Unit 10. Ecological Principles
  1. Many primary and higher-order consumers are opportunistic feeders.
  2. Decomposers compete with higher-order consumers for nutrients and energy. 
  3. Nutrient cycles involve both abiotic and biotic components of ecosystems.
  4. Energy transfer between tropic levels is in almost all cases less than 20% efficient.
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TLS Online TPP Program

#Question id: 2158

#Unit 2. Cellular Organization

Which of the following factors increase(s) the rate of simple (passive) diffusion of a solute across a phospholipid bilayer?
TLS Online TPP Program

#Question id: 13136

#Unit 10. Ecological Principles

The figure below illustrates the relationship between population density in the present generation (Nt) and population equilibrium density of this population in the next generation (Nt+1). The dashed reference line has a slope of 1. Which of the following represents equilibrium density of this population?
TLS Online TPP Program

#Question id: 5094

#Unit 5. Developmental Biology

Cell migration occurs extensively during ________.
TLS Online TPP Program

#Question id: 12409

#Unit 6. System Physiology – Plant

The Chemical Structure of ABA Determines Its Physiological Activity, 15 carbon compound 
a) The orientation of the carboxyl group at carbon 2 determines the cis and trans isomers of ABA. Nearly all the naturally occurring ABA is in the cis form
b) S enantiomer is the natural form; commercially available synthetic  ABA is a mixture of approximately equal amounts of the S and R forms.
c) The S enantiomer is the only one that is active in fast responses to ABA, such as stomatal closure
d) In long-term responses, such as seed maturation, only R-enantiomers are active
e) In contrast to the cis and trans isomers, the S and R forms cannot be interconverted in the plant tissue
Which of the following is the correct prediction about the active form  of ABA?
TLS Online TPP Program

#Question id: 13162

#Unit 4. Cell Communication and Cell Signaling

In the amoeba Dictyostelium discoideum, cAMP acts as an extracellular signalling molecule and binds to and signals via a G protein–coupled receptor; it is not a second messenger. Amoeba cells were transfected with genes encoding two fusion proteins: a Gα fused to cyan fluorescent protein (CFP), and a Gβ fused to yellow fluorescent protein (YFP). CFP normally fluoresces 490-nm light; YFP, 527-nm light. In which conditions fluorescence
energy transfer occur from CFP to YFP?