Transcript Answer: A Question No 3

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Sample Questions
Question No 1:
You set up an experiment to investigate the different rates at which soil and water heat and
cool. You use the following equipment:
Thermometers (measuring in °C)
Container of soil
Container of water
Radiation Lamp
Timer
You obtain the temperature of the soil and water over a period of time and collect the
following data:
Based on the results of the experiment, what is true about the heating and cooling rates of soil
and water?
A.
B.
C.
D.
Water heats faster, but cools slower.
Water heats and cools faster.
Soil heats faster, but cools slower.
Soil heats and cools faster.
Answer: D
Question No 2:
All proteins consist of a string of amino acids linked together by peptide bonds. Because of its
unique sequence of amino acids, every protein is distinct. Each protein folds into a specific
conformation when manufactured by cells. All proteins must attain three-dimensional
structures to properly function in the cell. While the peptide bonds between the amino acids
are relatively rigid, all the other chemical bonds within a protein are flexible and can contort
within certain limits.
The ability of a protein to fold depends on the flexibility of these chemical bonds. A small
protein of about 100 amino acids could undergo an astronomical number of trials and errors
before assuming its final structure. This sampling of many conformations before attaining the
right one would take far too long and so scientists hypothesize that there must be pathways
which guide individual proteins to the right conformations, thereby eliminating total
randomness in sampling. Three pathway models of protein folding have been proposed.
Diffusion-collision model
This model suggests that an amino acid within a protein can diffuse within its environment
until it collides with its specific partner amino acid, to which it adheres. When all the amino
acids, are involved in favorable interactions, the protein ceases to diffuse and the proper
conformation is attained.
Nucleation model
This model postulates that the acquisition of the proper fold within several amino acids
would trigger the folding process. These amino acids act as nucleation centers and cause a
domino effect in promoting protein folding. The protein can be imagined to sequentially
acquire its proper conformation beginning from the nucleation centers.
Hydrophobic-collapse model
Out of the 20 different amino acids, some are hydrophobic. A hydrophobic amino acid is one
that does not like to be associated with water but does like to be associated with others like
itself. In the hydrophobic-collapse model, hydrophobic amino acids in the protein collapse
into the center of the protein leaving the hydrophilic (water-loving) amino acids to surround
them and interact with water.
The nucleation model suggests that some amino acids are more important than others
whereas the diffusion-collision model supposes that all amino acids are equally important.
Which of the following statements is NOT true?
A. A mutation in an important amino acid in the nucleation model will have no effect
according to the diffusion-collision model.
B. A mutation in an amino acid, which is important in the nucleation model, will result in a
wrong conformation.
C. A mutation in an amino acid might affect proper protein conformation according to the
diffusion collision model.
D. A mutation in a certain amino acid might have an effect according to both the
nucleation model and the diffusion-collision model.
Answer: A
Question No 3:
SDS-PAGE is a technique used by scientists to separate proteins according to their size. The
compound SDS confers a uniform negative charge to individual proteins, causing these
negatively charged proteins to travel toward the anode (positive end) when placed in an
electric field. The migrating proteins are further placed in a uniform matrix (PAGE) in order to
separate the different sizes.
A bigger, heavier protein meets more resistance than a smaller, lighter one while traveling
through the matrix, and hence migrates more slowly. The size of a protein is measured in
Daltons (Da). The relationship between the logarithm values of the weights of seven proteins
and the distances they travel in the matrix in a given period of time is illustrated in the graph.
A list of the discrete data point values for each protein, as well as the corresponding weight,
is presented under the graph on the next page.
A protein of weight 45 000 Da would be expected to migrate to the region on the graph
marked:
A.
B.
C.
D.
W.
X.
Y.
Z.
Answer: A
Question No 4:
Background Information
If a characteristic is expressed in an organism, that is the organism’s phenotype. The genes
that determine that phenotype are called the organism’s genotype. A characteristic is
determined by the organism’s genes that were passed down by the parents. If a gene is
dominant, that gene will be expressed in the phenotype. If a gene is recessive, it will only be
expressed in the phenotype when two recessives are present in the genetic makeup of that
organism.
Description
A cat breeder is losing money because customers are buying cats that do not have white
paws, and the cat breeder has mostly white-pawed cats. She decides to experiment with
breeding with the six remaining cats that do not have white paws to see if she can produce
litters of kittens without white paws. A cat without white paws can be either pure for the
non-white pawed cats (homozygote) or a carrier for white paws (heterozygote). The trait for
having white paws is recessive.
A homozygote for the non-white = WW (non-white cat paws)
A heterozygote for white = Ww (non-white cat paws)
A homozygote for the white = ww (white cat paws)
You can create Punnett Squares to show the phenotypes that would result from two parent
cats breeding.
WW x WW cross yields all non-white pawed kittens.
Experiment
Group 1
The cat breeder breeds two cats that do not have white paws. She finds that the first
generation of kittens in this group does not have any white paws. When the first generation
of cats was bred, she finds that the second generation of these kittens is 1/8 white-pawed
and 7/8 not white-pawed.
Group 2
The cat breeder breeds two different cats that do not have white paws. She finds that the
first, second, and third generations of kittens in this group did not have any white paws.
Group 3
The cat breeder breeds two different cats that do not have white paws. She finds that the
first generation of kittens in this group has 1/4 with white paws and 3/4 without white paws.
She does not breed for a second generation in this group.
Which group contains parent cats that may be pure for not having white paws?
A. Group 1
B. Group 2
C. Group 3
D. None of the groups
Answer: B
Question No 5:
Graphs I-IV and Data Table I represent the motion of objects in one dimension as detected by
a motion detector. Motion in the positive direction represents motion away from the motion
detector and motion in the negative direction represents motion toward the motion
detector.
The data listed in Data Table I could be used to construct which graph?
A.
B.
C.
D.
Graph I
Graph II
Graph III
Graph IV
Answer: C
Question No 6:
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a
solution. The amount of solute that can be dissolved in a solvent at a given temperature is
called solubility. For most substances, solubility increases with temperature. When the
amount of solute dissolved in a solvent exceeds the solubility, the solution is called
supersaturated.
Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a
high temperature, and then slowly cooling the solution to room temperature. If a thin string
is dipped into it and left in the solution, the sugar in excess of the solubility at room
temperature will form sugar crystals around the string, making the sweet rock candy. The
solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees
Celsius) is plotted in the graph below.
How much sugar must be added to a solution of 50 g of sugar in 100 g of water at 45 degrees
Celsius in order for the solution to be supersaturated?
A.
B.
C.
D.
More than 10 grams
More than 20 grams
More than 100 grams
More than 200 grams
Answer: D
Question No 7:
The heart is an organ that pumps blood throughout the circulatory system in the body. Red
blood cells are a tissue in the body that carry nutrients to the body’s cells and waste away
from the body’s cells. The heart rate increases or decreases depending on the body’s needs to
transport nutrients and waste.
In an experiment, a female had her heart monitored. For one minute, she sat in a chair
quietly.
At the end of the first minute to the end of the third minute she did jumping jacks. Finally,
she sat again in the chair and waited until her heart rate went back to her resting heart rate
as measured in the first minute. After performing this experiment, the following graph was
created.
Which of the following tables accurately displays the information found in Graph 1
Answer: A
Question No 8:
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a
solution. The amount of solute that can be dissolved in a solvent at a given temperature is
called solubility.
For most substances, solubility increases with temperature. When the amount of solute
dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy
can be made by dissolving as much sugar in water, as solubility would allow at a high
temperature, and then slowly cooling the solution to room temperature. If a thin string is
dipped into it and left in the solution, the sugar in excess of the solubility at room
temperature will form sugar crystals around the string, making the sweet rock candy.
The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in
degrees Celsius) is plotted in the graph below.
In order for 250 g of sugar to completely dissolve in 100 g of water, the temperature of the
solution would have to be at a minimum of:
A.
B.
C.
D.
15 degrees Celsius.
25 degrees Celsius.
45 degrees Celsius.
65 degrees Celsius.
Answer: C
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