Cellular senescence may have evolved to protect organisms against cancer. Instead of dividing out of control, the cells die. Cellular senescence appears to be regulated by several tumor suppressor genes, especially p53.what is the most appropriate reason behind this,

1) Transcription factor p53 is thought to suppress tumorigenesis by causing cell arrest and senescence in response to short telomeres, DNA damage, and viral or external signals to divide

2) This factor can stop the cell cycle, cause cellular senescence in rapidly dividing cells, instruct genes to initiate cellular apoptosis, and activate DNA repair enzymes.

3) Induction of apoptosis or cellular senescence by p53 always beneficial.

TLS Online TPP Program

#Question id: 12343

#Unit 10. Ecological Principles

Hybrids between some related species of plants are sterile because the parent plants had different chromosome numbers. Occasionally the chromosome number of such a hybrid  plant doubles spontaneously. Which of the following best describes the descendants of those plants with the double chromosome number?

TLS Online TPP Program

#Question id: 12342

#Unit 10. Ecological Principles

Which of the following is a biological attribute that would most likely allow a species to become cosmopolitan in distribution?

TLS Online TPP Program

#Question id: 12341

#Unit 10. Ecological Principles

The figure shows population growth trajectories over time (as indicated by the arrows) of two stored-grain beetle  species  when  grown  together  under  constant  conditions.  Three  experiments  were  performed  that  differed only in the initial densities of the two species. Which of the following is the best interpretation of the experimental results?

TLS Online TPP Program

#Question id: 12340

#Unit 10. Ecological Principles

Keystone species are thought to have profound effects on the structure and composition of ecological communities because they

TLS Online TPP Program

#Question id: 12339

#Unit 10. Ecological Principles

If a species is a keystone predator, then its removal from a community should

TLS Online TPP Program

#Question id: 12338

#Unit 10. Ecological Principles

Ecology as a discipline directly deals with all of the following levels of biological organization except