Two eukaryotic proteins have one domain in common but are otherwise very different. Which of the following processes is most likely to have contributed to this phenomenon?

#Question id: 32283

#Unit 2. Cellular Organization

#Question id: 1717

#Unit 4. Cell Communication and Cell Signaling

Which of the following functions are macrophages unable to carry out?

#Question id: 11332

#Unit 10. Ecological Principles

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is that

 A) tropical communities are older.

 B) tropical regions generally have more available water and higher levels of solar radiation.

 C) higher temperatures cause more rapid speciation.

 D) diversity increases as evapotranspiration decreases.

#Question id: 10844

#Unit 10. Ecological Principles

In the formula for biotic potential (dN/dt = rIN), what does n stand for?

#Question id: 804

#Unit 1. Molecules and their Interaction Relevant to Biology

With respect to microRNAs, which, if any, of the following statements, is false?

a) A microRNA normally works by binding to perfectly complementary sequences within an RNA transcript, usually an mRNA.

b) Like the great majority of mRNAs an miRNA is usually produced as a larger precursor RNA that is capped and has a 3’ poly(A) tail.

c) The precursor miRNA undergoes different types of post-transcriptional cleavage by endoribonucleases that are specific for double-stranded target sequences.

d) A nuclear endoribonuclease called dicer cleaves the miRNA precursor so that it forms a stem-loop RNA.