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TLS Online TPP Program

#Question id: 12482

The Rb protein has been called the “master brake” of the cell cycle. How the Rb protein acts as a cell cycle brake?

#Unit 2. Cellular Organization
  1. Rb bound to E2F and function as transcriptional repressors because Rb recruits chromatin-modifying enzymes that promote deacetylation and methylation of specific histone lysines, causing chromatin to assume a condensed, transcriptionally inactive form.
  2. S phase CDKs and mitotic CDKs maintain Rb protein in the phosphorylated state throughout the S, G2, and early M phases.
  3. Rb bound to E2F and promotes ubiquitinylation of E2F and inhibits chromosomal segregation.
  4. Rb bound to E2F and promotes acetylation which prevents unloading of cohesins.
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TLS Online TPP Program

#Question id: 13182

#Unit 10. Ecological Principles

The MacArthur-Wilson equilibrium model of island biogeography predicts the number of species found on islands. The figure below depicts two volcanic islands located off a section of mainland coast.

The MacArthur-Wilson model predicts that the relative numbers of bird species on the mainland and two islands would be
TLS Online TPP Program

#Question id: 13183

#Unit 10. Ecological Principles

The MacArthur-Wilson equilibrium model of island biogeography predicts the number of species found on islands. The figure below depicts two volcanic islands located off a section of mainland coast.


According to the MacArthur-Wilson model, how would the number of bird species change from the time of an island's formation (assuming it remains constant in size and isolation)?
TLS Online TPP Program

#Question id: 13184

#Unit 10. Ecological Principles

The MacArthur-Wilson equilibrium model of island biogeography predicts the number of species found on islands. The figure below depicts two volcanic islands located off a section of mainland coast.

According to  the  MacArthur-Wilson model, the  number of  bird  species present on  Island 2  at  any  one  time is  a function of the relative rates of
TLS Online TPP Program

#Question id: 13185

#Unit 10. Ecological Principles

If a drop in sea level led Island 1 to double in area, the MacArthur-Wilson model predicts that the number of bird species found there would
TLS Online TPP Program

#Question id: 13186

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance

This model predicts that recruitment of new individuals into the population should be
TLS Online TPP Program

#Question id: 13187

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance


Which of the following factors is most likely to generate the seed density curve shown?