BIL150 Mallery exam 2 Questions With
Complete Solutions
Bacteria - CORRECT ANSWER-any of a group of microscopic organisms that are
prokaryotic, i.e., that lack a membrane-bound nucleus and organelles. Bacteria are
unicellular (one-celled) and may have spherical (coccus), rod-like (bacillus), or curved
(vibrio, spirillum, or spirochete) bodies. Different bacteria inhabit virtually all
environments, including soil, water, organic matter, and the bodies of eukaryotes
(multicellular animals). Some bacteria are known to be beneficial to humans and the
higher animals, while many others are harmful; bacteria are the chief cause of infectious
diseases in humans.
Prokaryote - CORRECT ANSWER-any self-contained cell or organism that lacks
internal unit membranes. Bacteria are among the best-known procaryotic organisms.
Procaryotes lack a nuclear membrane and most of the components of eucaryotic cells.
The cell membrane consists of a phospholipid unit membrane and constitutes the cell's
primary osmotic barrier. The cytoplasm includes ribosomes that carry out translation
and protein synthesis. The nuclear region usually consists of circular, double-stranded
deoxyribonucleic acid (DNA). Many procaryotes also contain accessory, self-replicating
genetic structures, called plasmids, with additional dispensable cell functions, such as
encoding proteins to inactivate antibiotics. The flagella are distinct from those of
eucaryotes in design and movement. The organelles that are present, such as storage
vesicles, are surrounded by a non-unit membrane consisting principally of proteins.
Archaebacteria - CORRECT ANSWER-aquatic or terrestrial microorganisms that exhibit
a diversity of shapes, including spherical, rod-shaped, and spiral forms. Archaebacteria
lack murein (ester lipids) in the cell walls, which is characteristic of eubacteria; instead,
they have ether lipids, as well as a number of different cell-wall constituents.
Archaebacteria also differ from eubacteria in the structure of their ribosomal RNA's,
which are used in genetic testing to assess the degree of genetic relatedness among
different species. The archaebacteria reproduce using a wide variety of mechanisms,
including binary and multiple fission, budding, and fragmentation. Archaebacteria
survive in a number of extreme environments, including very hot or saline ones.
Archaebacteria may be aerobic, anaerobic, or facultatively anaerobic in their metabolic
requirements. Some archaebacteria, such as Halobacterium, require a highly saline
,environment. Others, such as Methanobacterium, produce methane (CH4) as an end
product, while still others are dependent on sulfur for their metabolism. The latter group
are among the most thermophilic of the archaebacteria, surviving in temperatures
higher than 45 to 50 C (113 to 122 F).
Eubacteria - CORRECT ANSWER-any of a group of true bacteria species and one of
two major groups of prokaryotic organisms. The other major group, the archaebacteria,
are as different from eubacteria as either is from the eukaryotes. The division of the
bacteria into two groups has been suggested by ribosomal RNA studies of the genetic
information of the organisms. Eubacteria and archaebacteria are thought to have
evolved separately from a common ancestor early in Earth's history. Eubacteria and
archaebacteria differ in important characteristics, such as the number of ribosomal
proteins and the size and shape of the ribosomal S unit.
Eucaryote - CORRECT ANSWER-any cell or organism that possesses a clearly defined
nucleus, a description that excludes bacteria and blue-green algae. The eucaryotic cell
has a nuclear membrane, well-defined chromosomes (bodies containing the hereditary
material), mitochondria (cellular energy exchangers), a Golgi apparatus (secretory
device), an endoplasmic reticulum (a canal-like communication system within the cell),
&lysosomes (digestive apparatus within many cell types).
Virus - CORRECT ANSWER-an infectious agent of small size and simple composition
that can reproduce only in living cells of animals, plants, or bacteria. A virus consists of
a single-or double-stranded nucleic acid and at least one protein surrounded by a
protein shell, called a capsid. The nucleic acid carries the virus's genome--its collection
of genes--and may consist of either DNA or RNA. The protein capsid provides
protection for the nucleic acid and may contain enzymes that enable the virus to enter
its appropriate host cell. Some viruses are rod-shaped, others are icosahedral (a
roughly spherical shape that is actually a 20-sided polygon), and still others have
complex shapes consisting of a multisided "head" and a cylindrical "tail."
Cell division - CORRECT ANSWER-nucleus, chromosomes, centrioles, microtubules
(spindle fibers) microfilaments (cell furrow pinching it apart
, Information storage & transfer - CORRECT ANSWER-nucleus, chromosome, DNA-->
mRNA --> ribosomes --> enzymes & proteins
Energy conversion - CORRECT ANSWER-mitochondria
Manufactures membranes & products - CORRECT ANSWER-ribosomes, rough E.R.,
smooth E.R., Golgi apparatus and its vesicles
Lipid synthesis & drug detoxification - CORRECT ANSWER-smooth E.R.
Digestion & recycling - CORRECT ANSWER-lysosomes and food vacuoles
Conversion of H2O2 to water - CORRECT ANSWER-peroxisomes
Structural integrity - CORRECT ANSWER-cytoskeleton: microtubules, microfilaments,
intermediate filaments
Movement - CORRECT ANSWER-cilia and flagella, microtubules, microfilaments (actin
in muscles) and pseudopodia
Exchanges with the environment - CORRECT ANSWER-plasma membrane and
vesicles
Cell to cell connections - CORRECT ANSWER-tight junctions, desmosomes, gap
junctions, plasmodesma
Plant cell inter-cell communication - CORRECT ANSWER-plasmodesma
