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TLS Online TPP Program

#Question id: 3647

In the cell cycle: there are four main phases, G1, S, G2 and M phase. S phase is the :

#Unit 3. Fundamental Processes

  1. DNA synthesis phase

  2. cell division phase

  3. protein synthesis phase

  4. transcription phase

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TLS Online TPP Program

#Question id: 7762

#Unit 5. Developmental Biology

Correlation between life span and the ability of fibroblasts to repair DNA in various mammalian species, Repair capacity is represented in autoradiography by the number of grains from radioactive thymidine per cell nucleus. According to graph, which factor exist on x-axis ? Note that the y-axis (life span) is logarithmic.
TLS Online TPP Program

#Question id: 7763

#Unit 5. Developmental Biology

Two major sources of mutation are radiation and reactive oxygen species (ROS).The reactive oxygen species hypothesis for aging postulates that 
1) Senescence results from the accumulation of DNA, lipid, and protein damage inflicted by ROS of mitochondrial origin; and
2) Mitochondria of long-lived species should produce high ROS than do mitochondria of short-lived species.
3) the capacity of mitochondria to consume ROS might distinguish long-lived species from short-lived species, rather than differences in ROS generation. 
TLS Online TPP Program

#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.
TLS Online TPP Program

#Question id: 7765

#Unit 5. Developmental Biology

The enzyme complex or gene that maintains telomere integrity is________, which acts as an antisenescence complex. Mice and humans with its deficiencies age prematurely (Mitchell et al. 1999). Overexpressing or reactivating it in senescent cells extends longevity in mice without increasing cancer,
TLS Online TPP Program

#Question id: 7766

#Unit 5. Developmental Biology

The relationship between shortened telomeres and stem cell depletion has been seen in degenerative diseases such as mouse muscular dystrophy,

I) When____ is activated by damaged telomeres, DNA replication halts, and if the repair doesn’t work, apoptosis is initiated. If the cell is a stem cell or some other rapidly replicating cell, this will reduce the numbers of cells produced, and the lack of stem cells will produce an “aged” phenotype.

 II) When ____ is activated by damaged telomeres, DNA replication halts, repair do its work, apoptosis is inhibited. If the cell is a stem cell or some other rapidly replicating cell, this will increase the numbers of cells produced, and then these cells will produce an “aged” phenotype.

 Choose correct gene name with right statement
TLS Online TPP Program

#Question id: 7767

#Unit 5. Developmental Biology

How can evolution select for phenotypes that postpone reproduction or sexual maturity?” There is often a trade-off between reproduction and maintenance, and in many species reproduction and senescence are closely linked. Recent studies of mice, Caenorhabditis elegans, and Drosophila suggest that there is a conserved genetic pathway that regulates aging and that it can indeed be selected for. This pathway involves the response to insulin and insulin-like growth factors, Name of these transcription factors are