________ is a directional movement in response to a graded chemical stimulus.

Fill in the blank(s) with the appropriate word(s).


Chemotaxis

Biology & Microbiology

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Kuru is a degenerative disease of the central nervous system believed to be caused by which type of agent?

A) virus B) bacterium C) prion D) viroid E) protozoan

Biology & Microbiology

The macromolecule that can accomplish the widest range of biological functions are

A. carbohydrates. B. proteins. C. nucleic acids. D. lipids. E. glycolipids.

Biology & Microbiology

Consider the model for equilibrium number of species in a mainland (continental) region, as illustrated in Figure 20.23. What does this model say about the rate of extinction?

A) The rate of extinction decreases as a linear function of the number of species. B) The rate of extinction increases as a linear function of the number of species. C) The rate of extinction increases as a function of the number of species, but the rate of increase accelerates as the number of species becomes large.

Biology & Microbiology

What term describes the ectoderm, mesoderm, and endoderm?

A) Inner cell mass B) Extraembryonic membranes C) Primary germ layers D) Blastomeres

Biology & Microbiology