The anterioposterior axis of an embryo is established by
A. activin.
B. Hox genes.
C. cadherins.
D. noggin.
E. transforming growth factor.
B. Hox genes.
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Nucleotides are composed of a _____, a ______________, and a ____________.
Fill in the blank(s) with the appropriate word(s).
Which type of sensory receptors becomes more sensitive when damaged tissues produce prostaglandins?
A) deep pressure receptors B) photoreceptors C) pain receptors D) temperature receptors
According to the diversity-stability hypothesis:
A. Genetic diversity is the most important part of ecosystem stability. B. A loss of any species from an ecosystem leads to an approximately equal decline in stability. C. The loss of a few species from an ecosystem does significantly affect ecosystem functioning. D. Losing even a few species from an ecosystem causes a drastic decline in ecosystem stability. E. Every species has an important role in ecosystem function, but we cannot predict the effect of species loss.
__________ are electrically excitable cells that signal other cells by means of chemical messages. Fill in the blank(s) with the appropriate word(s)