line and others being pushed toward the surface to flatten and die and be sloughed off.
in the bone marrow other stem cells produce erythrocytes that lose their nucleus and
function for a few months in the bloodstream before they too die. such "dead end" cells
that reproduce no further
a. leave the cell cycle in a g0 phase, which immediately follows telophase.
b. leave the cell cycle in a g3 phase, which immediately follows g2.
c. halt in the midst of the s phase.
d. continually cycle but simply fail to go through cytokinesis.
e. reverse from g2 to g1.
7) present experimental evidence related to griffith's experiment and the identification
of the cell's genetic material.
when experimenting with streptococcus pneumoniae in the 1920's, griffith noticed that
some colonies were shiny and smooth and some were rough in appearance. he called
the shiny colonies, the s strain' and the rough colonies, the r' strain. when griffith
injected mice with the s strain, which he discovered were encapsulated, they died. when
he injected them with the r strain, they did not die. in trying to determine what factor
was responsible for the s strain's virulence, griffith heat-killed the s bacteria to destroy
the capsule. when he injected mice with the normally fatal s strain bacteria that had
been heat-killed, they did not die. however, if the heat-killed s strain bacteria were
mixed with harmless live r strain bacteria of the same species and injected, the mice did
die. surprisingly, living s strain bacteria were recovered from the bodies of the mice.
griffith concluded that some substance from the dead s strain bacteria passed to the r
strain bacteria, imparting virulence and the ability to form a capsule. avery and others
continued the search for the substance that "transformed" the r strain into the s strain.
hypothesis i: genetic material or "transforming substance" is protein.
hypothesis ii: genetic material or "transforming substance" is rna.
hypothesis iii: genetic material or "transforming substance" is dna.
in an experiment, neither heat-killed r strain nor heat-killed s strain can kill the mice.
a. supports hypothesis i
b. supports hypothesis ii
c. supports hypothesis iii
d. rejects hypothesis i only.
e. rejects hypothesis ii only.
f. rejects hypothesis iii only.g. does not support or provide information to reject any of
8) over the course of millions of years various environments have changed. as
grasslands slowly took the place of forests the inhabitants were forced to adapt or they
went extinct. during this time period the horse evolved from a small cat sized creature