During succession species that colonize in early seral stages tend to have different life-history characteristics than those that colonize in later seral stages ;

A) Early seral stage in succession

B) Late seral stage in succession

 i) Good seed dispersal ability

ii) Lower plant efficiency in low light

iii) Seed dispersal  by animal

iv) Slower the resource acquisition

v) Found large biomass

vi) Seed longevity is long type

Which of the following is the correct prediction about early and the late successional seral stage?

#Question id: 7761

#Unit 5. Developmental Biology

#Question id: 7762

#Unit 5. Developmental Biology

#Question id: 7763

#Unit 5. Developmental Biology

#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: 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,

#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