The  stele  is  the  central  part  of  the root  or  stem  containing  the  tissues  derived  from  the  Procambium.  These  include  vascular  tissue.

The  main  function  of  the  stele  is  to  provide structural  support  to  the  plant.

TLS Online TPP Program

#Id: 9565

#XL - T Zoology

Haldane’s rule: Hybrid sterility or hybrid inviability is often limited to the heterogametic sex. 

TLS Online TPP Program

#Id: 9566

#XL - T Zoology

Hamilton’s rule:  It states that an allele that causes an altruistic behavior will spread if the following condition is met (rb>C)

TLS Online TPP Program

#Id: 9567

#XL - T Zoology

Cope’s rule:  A proposed generalization that individual body size in animals tends to increase during evolution.

TLS Online TPP Program

#Id: 9568

#XL - T Zoology

Hitchhiking: Change in the frequency of an allele due to linkage with a selected allele at another locus.

TLS Online TPP Program

#Id: 9569

#XL - T Zoology

Dollo’s law:  A biological generalization positing that complex characters, once lost in evolution, are extremely unlikely to reappear and thus the loss of complex characters is virtually always irreversible.

TLS Online TPP Program

#Id: 9570

#XL - T Zoology

Van Valen law -  he found a surprising result: rather straight curves, implying that the probability of extinction is roughly constant.