The pseudopods of amoebas and certain other cells
are produced by the action of __________ and
motor proteins.
a. myosin
b. microtubules
c. intermediate filaments
d. microfilaments
e. all of these
Answer: d
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If cells of an individual contain the same set of genes, how do these cells become different from each other during development?
A) Different cell type-specific regulatory elements in DNA are created during development. B) Different cell type-specific regulatory elements in DNA are selectively lost during development. C) Differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell. D) Differences develop in promoter sequences that lead to different signals being produced by each type of cell.
What defines radial symmetry?
A. Only one plane of symmetry splits the organism into equal halves. B. Any plane of symmetry passing through the center of the organism splits it into equal halves. C. No planes of symmetry exist; the organism cannot be split into equal halves. D. Only four planes of symmetry passing through the center of the organism splits it into equal halves.
The phase of a population growth curve that comes after the lag phase is the
A. stable equilibrium phase. B. deceleration phase. C. exponential growth phase. D. death phase.
What is a regulatory protein for a gene? It binds to specific DNA sequences with high affinity and plays a predominant role in determining if a genome segment is transcribed or not.
a) the terminator b) the promotor c) the structural genes d) the repressor e) the operator