#Question id: 7764
#Unit 5. Developmental Biology
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.
#Question id: 7309
#Unit 5. Developmental Biology
Following statements are regarding to the molecular basis of the coincidence model in Arabidopsis.
A.
In Arabidopsis under short days, there is little overlap between CO mRNA
expression and daylight.
B.
CO protein does not accumulate to sufficient levels in the phloem to promote
the expression of the transmissible floral stimulus and the plant remains vegetative.
C. Under long days, the peak of CO mRNA abundance (at hours 12 through 16) overlaps with daylight (sensed by phyA and cryptochrome [cry]), allowing CO protein to accumulate.
D. CO activates FLC mRNA expression in the phloem, which
causes flowering when the FT protein is translocated to the apical meristem.
Which of the following is incorrect?
#Question id: 4972
#Unit 11. Evolution and Behavior
Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, what was true of Lystrosaurus?
#Question id: 1204
#Unit 4. Cell Communication and Cell Signaling
What factors are responsible for the specificity of G protein-coupled responses?
#Question id: 3652
#Unit 3. Fundamental Processes
Alkylating agents are electrophilic chemicals which readily add alkyl groups to various positions on nucleic acids. A common example is: