In amphibian eggs, a pigmented area called the ____ appears after fertilization.

A. gray matter
B. gray crescent
C. blastomere
D. cleavage plane
E. gray oocyte


Answer: B

Biology & Microbiology

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Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group.  This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated.  AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate.  ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate.  There are other regulators of this enzyme as well.  What is the role of AMP in this example?  

A.  Competitive inhibitor B.  Noncompetitive inhibitor C.  Allosteric inhibitor D.  Allosteric activator E.  Catalyst

Biology & Microbiology

Deserts are usually found between what

latitudes? a. 0?15 degrees b. 15?25 degrees c. 25?40 degrees d. 40?60 degrees e. 60?90 degrees

Biology & Microbiology

Which one of the following hormone pairs is antagonistic, in that they have opposing effects?

A) estrogen, progesterone B) epinephrine, norepinephrine C) glucagon, insulin D) oxytocin, prolactin E) thyroxine (T4 ) and triiodothyronine (T3 )

Biology & Microbiology

Why are individuals with Turner syndrome always female and individuals with Klinefelter syndrome always male?

What will be an ideal response?

Biology & Microbiology