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TLS Online TPP Program

#Id: 2262

Artificial selection- Genetically improving animals and plants by breeding together the best individuals in their fields and flocks.


#Unit 11. Evolution and Behavior #Rate of change in gene frequency through natural selection #Part B Pointers
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TLS Online TPP Program

#Id: 4734

#Unit 5. Developmental Biology
TLS Online TPP Program

#Id: 4735

#Unit 5. Developmental Biology

In C. elegans
When sperm fuses with the egg cell membrane, polyspermy is prevented by the rapid synthesis of chitin by the newly fertilized egg.
TLS Online TPP Program

#Id: 4736

#Unit 5. Developmental Biology

The zygote of C. elegans exhibits rotational holoblastic cleavage.
TLS Online TPP Program

#Id: 4737

#Unit 5. Developmental Biology

During early cleavage, each asymmetrical division produces:

  • One founder cell (denoted AB, E, MS, C, and D) that produces differentiated descendants
  • One stem cell (the P1–P4 lineage) 
TLS Online TPP Program

#Id: 4738

#Unit 5. Developmental Biology

The anterior-posterior axis is determined before the first cell division, and the cleavage furrow is located asymmetrically along this axis of the egg, closer to what will be the posterior pole.
TLS Online TPP Program

#Id: 4739

#Unit 5. Developmental Biology

The stem cell lineage always undergoes meridional ,division to produce
(1) An anterior founder cell (AB)
(2) A posterior cell (P1) that will continue the stem cell lineage.