#Question id: 19183
#Unit 13. Methods in Biology
#Question id: 32576
#Unit 2. Cellular Organization
#Question id: 4647
#Unit 11. Evolution and Behavior
The treeʹs horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Letʹs say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled V—Z, has been most successful in terms of the percent of its derived species that are extant?
#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?
#Question id: 2954
#Unit 2. Cellular Organization
Cyclin concentrations are highest during which periods of the cell cycle?