A．Develop normally.( )
B．Stop cell division.
C．Have abnormal cell migration(迁移).
D．Don't exhibit action potentials.

A．Is complementary to mRNA.
B．Forms double-stranded RNA.
C．Joins with the 30S subunit.
D．Inhibits protein synthesis.

A．The genes are located outside the nucleolus(核仁).
B．The genes are transcribed by RNA polymerase III.
C．The promoter region of the 5S rRNA gene is internal to the gene.
D． all of the above

A．One copy of each ribosomal transcription unit.
B．Thousands of copies of the 5S rRNA gene.
C．Two copies of each gene for rRNA and ribosomal proteins.
D．Two copies of each gene for rRNA and one copy of each ribosomal proteingene.

A．Transmission(透射) electron microscope
B．Scanning electron microscope
C．Differential centrifugatioin(差速离心)
D．X-ray crystallography

A． Water leaves the cell by osmosis.
B． C1- is diffusing through transmembrane channels.
C． C1- diffusion is aided by a mobile carrier.
D．An active transport symport transports C1-/H+.
E．None of the above

A．Stomach(胃) and kidneys
B．Smooth muscle
C．Heart muscle
D．Intestinal epithelial tissue(肠表皮组织)

A．降低细胞质中Ca2+的浓度；
B．提高细胞质中Ca2+的浓度；
C．降低内质网中Ca2+的浓度；
D．降低线粒体中Ca2+的浓度

A．Protein kinase A
B．Phosphorylase kinase
C．Glycogen phosphorylase
D．Protein phosphatase
E． Protein phosphatase inhibitor-1

A．25-50% of the pre-rRNA is degraded
B． Pre-rRNA binds to ribosomal protein
C． Pre-rRNA is cut to form three classes of rRNA
D．Pre-rRNA is methylated
E．The rRNA gene for the 40S subunit is transcribed separately