TLS Online TPP Program

#Question id: 5122


In amphibia, when epidermal (ectodermal) and mesodermal cells are brought together in a mixed aggregate, the epidermal cells move to the periphery of the aggregate, and the mesodermal cells move to the inside by the process of selective affinity. Which of the following statement describe the phenomena of selective affinity?

#Unit 5. Developmental Biology
  1. The inner surface of the ectoderm has a positive affinity for mesodermal cells and a negative affinity for the endoderm, whereas the mesoderm has positive affinities for both ectodermal and endodermal cells.

  2. The inner surface of the ectoderm has a negative affinity for mesodermal cells and a positive affinity for the endoderm, whereas the mesoderm has negative affinities for both ectodermal and endodermal cells.

  3. The inner surface of the ectoderm has a positive affinity for mesodermal cells and a positive affinity for the endoderm, whereas the mesoderm has positive affinities for both ectodermal and endodermal cells.

  4. The inner surface of the ectoderm has a negative affinity for mesodermal cells and a negative affinity for the endoderm, whereas the mesoderm has negative affinities for both ectodermal and endodermal cells

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TLS Online TPP Program

#Question id: 13126

#Unit 10. Ecological Principles

Which point in the graph shows -Rate of population growth is highest.


TLS Online TPP Program

#Question id: 13127

#Unit 10. Ecological Principles

Which point in the graph shows -Per capita growth rate is highest


TLS Online TPP Program

#Question id: 13128

#Unit 10. Ecological Principles

Which point in the graph shows -Both population and per capita growth rates are positive but decelerating


TLS Online TPP Program

#Question id: 13129

#Unit 10. Ecological Principles

Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation  and  on  egg-to-adult survival.  From  a  large  source  population, they  randomly  assigned  eggs  to  three experimental  populations  of  size  N,  equal  to  20,  60,  and0100.  For  later  generations,  they  collected  N  eggs  from each  population  and  moved  them  into  identical  vials  that  co0ntained  f2re0sh  me4d0ium.  Th6e0y  coun8te0d  the  number  of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by  scoring  alleles  at  several  polymorphic  loci  and  expressed  as  the  average  number  of  alleles  at  those  loci.  The results are summarized in Figure 1 and Figure 2 below.

Based on Figure 1, which of the following best describes the change in genetic variation over time? 

TLS Online TPP Program

#Question id: 13130

#Unit 10. Ecological Principles

Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation  and  on  egg-to-adult survival.  From  a  large  source  population, they  randomly  assigned  eggs  to  three experimental  populations  of  size  N,  equal  to  20,  60,  and0100.  For  later  generations,  they  collected  N  eggs  from each  population  and  moved  them  into  identical  vials  that  co0ntained  f2re0sh  me4d0ium.  Th6e0y  coun8te0d  the  number  of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by  scoring  alleles  at  several  polymorphic  loci  and  expressed  as  the  average  number  of  alleles  at  those  loci.  The results are summarized in Figure 1 and Figure 2 below.


Which process best explains the dynamics of genetic variation observed in this experiment? 

TLS Online TPP Program

#Question id: 13131

#Unit 10. Ecological Principles

Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation  and  on  egg-to-adult survival.  From  a  large  source  population, they  randomly  assigned  eggs  to  three experimental  populations  of  size  N,  equal  to  20,  60,  and0100.  For  later  generations,  they  collected  N  eggs  from each  population  and  moved  them  into  identical  vials  that  co0ntained  f2re0sh  me4d0ium.  Th6e0y  coun8te0d  the  number  of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by  scoring  alleles  at  several  polymorphic  loci  and  expressed  as  the  average  number  of  alleles  at  those  loci.  The results are summarized in Figure 1 and Figure 2 below.


The numbers of adult flies that emerged from the three populations in the first generation are closest to which of the following?