#Question id: 641
#Unit 1. Molecules and their Interaction Relevant to Biology
Which of the following does NOT describe a mechanism that cells use to regulate enzyme activities?
A. Cells control enzyme activity by phosphorylation and dephosphorylation.
B. Cells control enzyme activity by the binding of small molecules.
C. Cells control the rates of diffusion of substrates to enzymes.
D. Cells control the rates of enzyme degradation.
E. Cells control the rates of enzyme synthesis.
F. Cells control the targeting of enzymes to specific organelles.
#Question id: 14766
#Unit 2. Cellular Organization
#Question id: 19083
#Unit 6. System Physiology – Plant
#Question id: 6969
#Unit 5. Developmental Biology
In Xenopus, the elongation of the mesoderm toward the anterior results from the intercalation of cells during a process called:
#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?