During ammonium assimilation, requires two enzymes converting ammonium to amino acids. Each of which is Glutamine synthetase (GS), given below some statements about GS ;

a) GS transfers the amide group of glutamine to 2-oxoglutarate, yielding two molecules of glutamate

b) it requires a divalent cation such as Mg2+, Mn2+, or Co2+ as a cofactor

c) Plants contain two classes of GS, one in the cytosol and the other in root plastids or shoot chloroplasts

d) The cytosolic forms are expressed in germinating seeds or in the vascular bundles of roots and shoots and produce glutamate for intercellular nitrogen transport

e) The GS in root plastids generates amide nitrogen for local consumption; the GS in shoot chloroplasts reassimilates photorespiratory NH4+

f) Light and carbohydrate levels alter the expression of the cytosolic forms of the enzyme, but they have little effect on the plastid forms.

Which of the following statements is correct?

#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?

#Question id: 13132

#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 other process appears to have substantially influenced the outcome of this experiment? 

#Question id: 13133

#Unit 10. Ecological Principles

The diagram below depicts three general types of survivorship curves. Only the form of the curve is important, not its absolute scale. Which of the following statements is LEAST likely to be true?

#Question id: 13134

#Unit 10. Ecological Principles

Which  of  the  graphs  below  represents the  relationship between  population  size  (N)  and  population  growth  rate (dN/dt) for a population showing exponential growth?

#Question id: 13135

#Unit 10. Ecological Principles

#Question id: 13136

#Unit 10. Ecological Principles

The figure below illustrates the relationship between population density in the present generation (Nt) and population equilibrium density of this population in the next generation (Nt+1). The dashed reference line has a slope of 1. Which of the following represents equilibrium density of this population?