TLS Online TPP Program

#Question id: 10919


Both of these observations—________X__________and________Y__________—support the existence of mass flow in the sieve elements of the phloem.

#Unit 6. System Physiology – Plant
  1. X- retrieve any sugars lost to the apoplast by leakage, and  Y- perhaps to reload sugars at the termination of sieve tubes
  2. X-the lack of bidirectional transport in a single sieve element and,  Y- similar velocities for solutes and water
  3. X-positive pressure gradient and,   Y- turgor pressure higher in sieve elements of sources than to sink 
  4. X-the bidirectional transport in a single sieve element and,   Y- different velocities for solutes and water
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TLS Online TPP Program

#Question id: 11153

#Unit 9. Diversity of Life Forms

A researcher wants to determine the genetic relatedness of several breeds of dog (Canis familiaris). The researcher should compare homologous sequences of __________ that are known to be __________.

TLS Online TPP Program

#Question id: 11152

#Unit 9. Diversity of Life Forms

When sufficient heat is applied, double-stranded DNA denatures into two single-stranded molecules as the heat breaks all of the hydrogen bonds. In an experiment, molecules of single-stranded DNA from species X are separately hybridized with putatively homologous single-stranded DNA molecules from five species (A-E). The hybridized DNAs are then heated, and the temperature at which complete denaturation occurs is recorded. Based on the data below, which species is probably most closely related to species X?


TLS Online TPP Program

#Question id: 11151

#Unit 9. Diversity of Life Forms

What conclusion can be drawn validly from these data?

TLS Online TPP Program

#Question id: 11124

#Unit 9. Diversity of Life Forms

A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals with the homologous human gene. The sequence homology between each speciesʹ version of the gene and the human gene is presented as a percentage of similarity.

What probably explains the inclusion of rabbits in this research?

TLS Online TPP Program

#Question id: 11123

#Unit 9. Diversity of Life Forms

Cladograms (a type of phylogenetic tree) constructed from evidence from molecular systematics are based on similarities in

TLS Online TPP Program

#Question id: 11122

#Unit 9. Diversity of Life Forms

Phylogenetic hypotheses (such as those represented by phylogenetic trees) are strongest when