USABO OPEN EXAM PRACTICE QUESTIONS WITH
VERIFIED SOLUTIONS NEW MODIFIED TESTED
AND GRADED A+ LATEST UPDATE
You examine a leaf cross-section under a microscope and find many loosely
packed cells. These cells have many chloroplasts and relatively thin cell walls.
These cells are:
A. collenchyma.
B. endodermis.
C. parenchyma.
D. schlerenchyma.
E. xylem --CORRECT ANSWER--C. parenchyma.
Parenchyma cells have primary walls that are relatively thin and flexible.
Parenchyma cells are often depicted as "typical" plant cells because they
generally are the least specialized. Tissue comprised of parenchyma may
contain few or many air spaces and the cells may or may not contain
chloroplasts. Chloroplast containing parenchyma cells are often referred to as
Chlorenchyma.
Which of the following would be most likely to increase competition among the
members of the vole population in a given area?
A. An increase in the number of hawk predators
B. An increase in the reproduction rate of voles
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,C. An increase in temperature
D. An increase in the food supply
E. An epidemic of rabies within the vole population --CORRECT ANSWER--
B. An increase in the reproduction rate of voles
Resource limitation in crowded populations can stop population growth.
Population density intensifies intraspecific competition for declining nutrients,
resulting in a lower birth rate.
Tobacco mosaic virus has RNA rather than DNA as its genetic material. If the
RNA genome from a tobacco mosaic virus is mixed with proteins from a human
rhinovirus, the result is a mixed virus. If that virus could infect a cell and
reproduce, what would you expect the resulting viruses to be like?
A. A hybrid including genetic material from tobacco mosaic virus and proteins
from the rhinovirus
B. A hybrid including proteins from tobacco mosaic virus and genetic material
from the rhinovirus
C. Rhinovirus
D. Tobacco mosaic virus
E. No viruses would result because no viral DNA was present --CORRECT
ANSWER--D. Tobacco mosaic virus
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,Virus genomes may consist of double-stranded DNA, single-stranded DNA,
double-stranded RNA, or single-stranded RNA depending on the specific type
of virus. Tobacco mosaic virus has a rigid, rodshaped capsid. The genetic
material from the tobacco mosaic virus serves as the template for the human
rhinovirus to replicate itself and produce new capsid proteins by transcription
and translation. The new viral DNA and capsid proteins assemble into tobacco
mosaic virus particles, which then leave the cell.
An amphipathic molecule is a molecule that is characterized by:
A. 2 different forms that are mirror images of each other.
B. an amino group.
C. a hydrophilic end and a hydrophobic end.
D. a positively charged end and a negatively charged end.
E. rarely being found in cell membranes. --CORRECT ANSWER--C. a
hydrophilic end and a hydrophobic end.
An amphipathic molecule is a phospholipid that has both a hydrophilic region
and a hydrophobic region.
The function of a molecular chaperone is to:
A. act as an energy source during the polymerization of amino acids into a
polypeptide.
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, B. act as a carrier molecule and bring "activated" monomers to a polymer for
incorporation.
C. bind to specific structures on the polypeptide in order to assist the folding of
a protein into its correct three dimensional shape.
D. unfold proteins with the incorrect three-dimensional shape and refold them
into the proper shape.
E. transport rRNA from the nucleus to the cytoplasm. --CORRECT ANSWER--
C. bind to specific structures on the polypeptide in order to assist the folding of
a protein into its correct three dimensional shape.
Chaperonins (also called chaperone proteins) are protein molecules that assist in
the proper folding of other proteins. Molecular chaperones do not actually
specify the correct final structure of a polypeptide. They work instead by
keeping the new polypeptide segregated from "bad influences" in the
cytoplasmic environment while it spontaneously folds.
Ethidium Bromide is used in electrophoresis of DNA fragments because it:
A. makes the fragments visible under UV light.
B. makes the DNA fragments more mobile in the gel.
C. increases the conductivity of electricity through the gel.
D. helps determine the size of the fragments.
E. maintains a stable pH. --CORRECT ANSWER--A. makes the fragments
visible under UV light.
Page 4 of 93
VERIFIED SOLUTIONS NEW MODIFIED TESTED
AND GRADED A+ LATEST UPDATE
You examine a leaf cross-section under a microscope and find many loosely
packed cells. These cells have many chloroplasts and relatively thin cell walls.
These cells are:
A. collenchyma.
B. endodermis.
C. parenchyma.
D. schlerenchyma.
E. xylem --CORRECT ANSWER--C. parenchyma.
Parenchyma cells have primary walls that are relatively thin and flexible.
Parenchyma cells are often depicted as "typical" plant cells because they
generally are the least specialized. Tissue comprised of parenchyma may
contain few or many air spaces and the cells may or may not contain
chloroplasts. Chloroplast containing parenchyma cells are often referred to as
Chlorenchyma.
Which of the following would be most likely to increase competition among the
members of the vole population in a given area?
A. An increase in the number of hawk predators
B. An increase in the reproduction rate of voles
Page 1 of 93
,C. An increase in temperature
D. An increase in the food supply
E. An epidemic of rabies within the vole population --CORRECT ANSWER--
B. An increase in the reproduction rate of voles
Resource limitation in crowded populations can stop population growth.
Population density intensifies intraspecific competition for declining nutrients,
resulting in a lower birth rate.
Tobacco mosaic virus has RNA rather than DNA as its genetic material. If the
RNA genome from a tobacco mosaic virus is mixed with proteins from a human
rhinovirus, the result is a mixed virus. If that virus could infect a cell and
reproduce, what would you expect the resulting viruses to be like?
A. A hybrid including genetic material from tobacco mosaic virus and proteins
from the rhinovirus
B. A hybrid including proteins from tobacco mosaic virus and genetic material
from the rhinovirus
C. Rhinovirus
D. Tobacco mosaic virus
E. No viruses would result because no viral DNA was present --CORRECT
ANSWER--D. Tobacco mosaic virus
Page 2 of 93
,Virus genomes may consist of double-stranded DNA, single-stranded DNA,
double-stranded RNA, or single-stranded RNA depending on the specific type
of virus. Tobacco mosaic virus has a rigid, rodshaped capsid. The genetic
material from the tobacco mosaic virus serves as the template for the human
rhinovirus to replicate itself and produce new capsid proteins by transcription
and translation. The new viral DNA and capsid proteins assemble into tobacco
mosaic virus particles, which then leave the cell.
An amphipathic molecule is a molecule that is characterized by:
A. 2 different forms that are mirror images of each other.
B. an amino group.
C. a hydrophilic end and a hydrophobic end.
D. a positively charged end and a negatively charged end.
E. rarely being found in cell membranes. --CORRECT ANSWER--C. a
hydrophilic end and a hydrophobic end.
An amphipathic molecule is a phospholipid that has both a hydrophilic region
and a hydrophobic region.
The function of a molecular chaperone is to:
A. act as an energy source during the polymerization of amino acids into a
polypeptide.
Page 3 of 93
, B. act as a carrier molecule and bring "activated" monomers to a polymer for
incorporation.
C. bind to specific structures on the polypeptide in order to assist the folding of
a protein into its correct three dimensional shape.
D. unfold proteins with the incorrect three-dimensional shape and refold them
into the proper shape.
E. transport rRNA from the nucleus to the cytoplasm. --CORRECT ANSWER--
C. bind to specific structures on the polypeptide in order to assist the folding of
a protein into its correct three dimensional shape.
Chaperonins (also called chaperone proteins) are protein molecules that assist in
the proper folding of other proteins. Molecular chaperones do not actually
specify the correct final structure of a polypeptide. They work instead by
keeping the new polypeptide segregated from "bad influences" in the
cytoplasmic environment while it spontaneously folds.
Ethidium Bromide is used in electrophoresis of DNA fragments because it:
A. makes the fragments visible under UV light.
B. makes the DNA fragments more mobile in the gel.
C. increases the conductivity of electricity through the gel.
D. helps determine the size of the fragments.
E. maintains a stable pH. --CORRECT ANSWER--A. makes the fragments
visible under UV light.
Page 4 of 93
