Acetylcholine (ACh), released from parasympathetic nerve fibers, activates muscarinic (M2) receptors in the SA node.

TLS Online TPP Program

#Id: 1316

#Unit 4. Cell Communication and Cell Signaling

G protein coupled receptor contains seven membrane-spanning α helices & heterotrimeric G protein.

TLS Online TPP Program

#Id: 3862

#Unit 5. Developmental Biology

Early on during aggregation, gene expression requires the activity of cAMP-dependent protein kinase.

TLS Online TPP Program

#Id: 5946

#Unit 10. Ecological Principles

Deserts are not very efficient at converting huge amounts of incident energy from sunlight into plant biomass.  Most ecosystems based on phytoplankton have very low efficiencies, usually less than 0.5%.

Photosynthetic efficiency of an ecosystem as a whole varies between 1% and 2%.

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#Id: 4784

#Unit 5. Developmental Biology

In an unperturbed embryo, both ABa and ABp contact the EMS blastomere, but only ABp contacts the P2 cell.

TLS Online TPP Program

#Id: 8639

#Unit 2. Cellular Organization

Phosphorylation of Whi5 promotes its export out of the nucleus, allowing the transcription factor complex SBF to induce transcription of the G1/S phase cyclin genes CLN1 and CLN2.