#Question id: 10360
#Unit 6. System Physiology – Plant
How much ATP require in the nitrogen fixation or conversion of ammonium assimilation in the system?
#Question id: 10357
#Unit 6. System Physiology – Plant
Why the glutamine and glutamate will not be transported while asparagine will prefer to be transported?
#Question id: 10356
#Unit 6. System Physiology – Plant
Why the GS and GOGAT is activated in light and while the AS is inhibited?
#Question id: 10354
#Unit 6. System Physiology – Plant
One of the enzyme that are involve in the ammonium assimilation is Asparagine synthetase (AS), some statements given below about AS such as,
a) This enzyme that catalyzes this reaction, is found in the cytosol of leaves and roots and in nitrogen-fixing nodules
b) High levels of light and carbohydrate inhibit the expression of genes coding for AS and the activity of the enzyme
c) Conditions of ample energy stimulate AS, thus they favor nitrogen assimilation into glutamine and glutamate
d) Energy-limited conditions inhibit GS and GOGAT, stimulate AS, and thus favor nitrogen assimilation into asparagine, a compound that is rich in nitrogen and sufficiently stable for long-distance transport or long term storage
Which of the following statements about AS is correct?
#Question id: 10348
#Unit 6. System Physiology – Plant
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: 10347
#Unit 6. System Physiology – Plant
NH4+ is toxic to plants, inhibit dinitrogenase and also interfere energy metabolism by dissociating ATP formation from ETC in both mitochondria and chloroplasts. What will plant cells do to avoid this problem?
a) Plant cells avoid ammonium toxicity by rapidly converting the ammonium generated from nitrate assimilation or photorespiration into nitrate
b) Plant cells avoid ammonium toxicity by rapidly converting the ammonium generated from nitrate assimilation or photorespiration into amino acids
c) The pathway for this conversion involves the sequential actions of glutamine synthetase (GS) and glutamate synthase (GOGAT)
d) The pathway for this conversion involves the sequential actions of Aspartate aminotransferase (Asp-AT) and Asparagine synthetase (AS)
Which of the above statements is incorrect?