USABO PRACTICE EXAM QUESTIONS WITH ALL CORRECT ANSWERS GRADED A+
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USABO
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USABO
USABO PRACTICE EXAM QUESTIONS WITH ALL CORRECT ANSWERS GRADED A+
Insulin release results in all of the following physiological effects EXCEPT: - Answer- decreased glycogen stores in liver cells
The endosperm of a plant with "monosporic" development has 72 chromosomes. How many chromosomes does ...
USABO PRACTICE EXAM QUESTIONS
WITH ALL CORRECT ANSWERS
GRADED A+
Insulin release results in all of the following physiological effects EXCEPT: - Answer-
decreased glycogen stores in liver cells
The endosperm of a plant with "monosporic" development has 72 chromosomes. How
many chromosomes does the egg cell have? - Answer-24
An allergic reaction is caused by an antigen with this class of immunoglubin: - Answer-
IgE
What effect do sexual processes (meiosis and fertilization) have on allele frequencies in
a population? - Answer-They have no direct effect on allele frequencies.
A mutation in the gene encoding cyclin D: - Answer-A,B, or C
The velocity of carrier-mediated diffusion across cellular membranes: - Answer-can
increase up to a maximum value
Insulin injected by diabetics to control blood sugar levels is derived from bacteria whose
DNA has been modified by the addition of the human gene for insulin, which is then
produced by the prokaryotes. This is an example of: - Answer-genetic engineering
Isolated RNA molecules are generally less stable than DNA at physiological pH
because: - Answer-RNA has ribose.
Which of the following molecules is able to cross the lipid bilayer? - Answer-steroid
hormones
If the rate constant of a first order reaction that converts substrate S into product P is
0.693 min -1 then what is the half life of the reaction? - Answer-1.000 min
The local swimming pool is contaminated with an organism that is causing "swimmers
itch." You think you have identified cyanobacteria in your sample. Which features would
you expect this organism to LACK? - Answer-nucleolus
Suppose radioactive thymine was added to an actively dividing culture of E.coli bacteria.
What would happen if a cell replicated once in the presence of this radioactive base? -
Answer-DNA in both daughter cells would be radioactive
,Questions 9 & 10 refer to the following information. The concentration of ions inside
anamoeba is expressed below as ion-units per milliliter. The composition of the
extracellular environment (ECE) is given for comparison. Assume the amoeba has been
in the environment for some time.
As the number of (+) and (-) ions in the amoeba and in the ECE are not equal, one
might assume that: - Answer-other ions are also involved.
Questions 9 & 10 refer to the following information. The concentration of ions inside an
amoeba is expressed below as ion-units per milliliter. The composition of the
extracellular environment (ECE) is given for comparison. Assume the amoeba has been
in the environment for some time.
The differences in concentration of K+ and Na+ inside and outside of the amoeba
indicate that: - Answer-energy has been expended.
. Five events occur in a cell constituting a cause-and-effect sequence: 1. an enzyme is
manufactured at the ribosomes 2. cellulose is deposited in a cell wall 3. a molecule of
RNA is transcribed 4. a carbohydrate polymer is synthesized 5. a nucleic acid migrates
from nucleus to ribosome - Answer-3,5,1,4,2
When bacterial cells multiply maximally during the logarithmic phase, the total number
of cells (b) after some time interval (t) is equal to the original number of cells (B)
multiplied by 2n , where n is the number of generations formed during the time interval:
n = t/g and b = (B)(2n ). The generation time (g) for type A cells is 28 minutes (assume
no cell death). Estimate the LEAST amount of time required for a population of type A
cells to increase by 300 percent - Answer-approximately 42 minutes
A population of 2800 flowers is in Hardy-Weinberg equilibrium, and 2352 of them are
red in color. The red allele [R]is the dominant allele; the allele for white color [r] is
recessive. What would be the frequency of heterozygotes in the population? - Answer-
.48
The cause of trisomy 21 is: - Answer-error during meiosis
The molecular weight of fumarate is 160.0. How many grams of fumarate are there in
200 mL of a 0.1 M fumarate solution? - Answer-3.20 grams
Replacement of a lysine with a glycine in a protein could result in all of the following
EXCEPT a : - Answer-loss of a negatively charged side chain.
The bacterial genome was sequenced and a mutation found in a gene adjacent to β-
galactoside. How would you best explain these research findings? The: - Answer-
mutation renders the enzyme responsible for lactose transport sensitive to high
temperatures.
Researchers found that the arginine code AGG is poorly represented in genes of E.coli.
Interestingly, they also found that this triplet, when present, binds to the ribosome 7-9
base pairs upstream from the starting ATG triplet (methionine). What does this
, information suggest in regard to the AGG codon? - Answer-it may have a regulatory
function in the cell
The above pedigree results from a rare SEX-LINKED disease. If individual 1 and 2 have
a baby, what is the likelihood that the child, noted with a ?, will have the disease? -
Answer-0% if it is a girl; 50% if it is a boy
The diversity of animal and plant species found on the Galapagos Islands differs from
that of the mainland because of: - Answer-divergent evolution
In many species of flowering plants, the characteristics of the flower; its scent, color,
time of flowering, time of day it opens, kind and amount of food it offers, are matched to
the pollinating organism's size, form, physiology and reproductive cycle. The term that
describes this relationship is: - Answer-coevolution
Mountain goats may have a thicker coat of hair than goats at lower altitudes in the same
general geographical area. This adaptation to the cooler climate of the mountains most
likely arose as a result of: - Answer-directional selection.
A given polyclonal antibody molecule can bind to: - Answer-more than one molecule of
the same antigen per antibody molecule.
If a mouse is exposed to cycles of 12 hours of light followed by 12 hours of dark, the
mouse is mostly active in the dark and has a rest-activity cycle of 24 hours. If the mouse
is then kept in a constantly dark environment, the period of the rest-activity cycle is
slightly less than 24 hours. Why does the mouse's cycle shorten in the dark
environment? - Answer-the mouse's circadian clock requires environmental cues to
reset it
Why is pepsinogen secreted as a zymogen into the stomach? To: - Answer-prevent
digestion of the gastric glands.
The anatomy of an animal from a cold climate differs from that of an animal from the
tropics in that: - Answer-the animal from the cold climate has smaller ears.
A person suffering from nerve gas exposure is given atropine to counteract the effects.
Why? - Answer-atropine blocks the acetylcholine receptor which blocks the excess
acetylcholine lingering in the synaptic cleft
Which of the following does NOT describe synovial joints? - Answer-bones held
together by cartilage
Which of the following processes aid in skeletal muscle relaxation after contraction? -
Answer-acetylcholinesterease degrades acetylcholine
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