ACT Science : How to find research summary in chemistry
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Example Questions
Example Question #901 : Act Science
The above chemical equation describes the dissociation of carbonic acid 
When carbon dioxide 
To study this effect, the student obtains a mixture of carbonic acid, bicarbonate, and hydrogen ion. Next, the student conducts trials in which she adds a certain amount of one of the chemicals one at a time and then measures how the concentrations of each chemical change after each addition.
pH is a measure of hydrogen ion concentration and is used to measure acidity. A pH of 7 is neutral, while a low pH corresponds to a high concentration of hydrogen ions, or an acid. What can we infer would happen to the pH of a person's blood if a large amount of carbon dioxide were to be produced in that person's body, such as during exercise?
The person's blood pH would not change.
The person's blood pH would increase and then decrease.
The person's blood pH would decrease and then increase.
The person's blood pH would decrease.
The person's blood pH would increase.
The person's blood pH would decrease.
The correct answer is that this person's blood pH would decrease. With more carbon dioxide in the blood, as the passage states, more carbonic acid would be present. Therefore, according to the passage's description of equilibrium, equilibrium would shift right and produce more bicarbonate and hydrogen ions. This would increase the concentration of hydrogen and therefore lower the pH.
Example Question #212 : Chemistry
The above chemical equation describes the dissociation of carbonic acid
When carbon dioxide
To study this effect, the student obtains a mixture of carbonic acid, bicarbonate, and hydrogen ion. Next, the student conducts trials in which she adds a certain amount of one of the chemicals one at a time and then measures how the concentrations of each chemical change after each addition.
What can we infer would happen to one of the student's trials if the student added both bicarbonate ion and hydrogen ion to that trial?
The reaction's equilibrium would shift farther to the left than if the student had only added one of the reactants.
The reaction's equilibrium would shift slightly to the left.
The reaction's equilibrium would shift farther to the right than if the student had only added one of the reactants.
The reaction's equilibrium would shift slightly to the right.
The reaction's equilibrium would remain constant.
The reaction's equilibrium would shift farther to the left than if the student had only added one of the reactants.
If the student adds either bicarbonate ion or hydrogen ion, we know that the equation's equilibrium will shift to the left. So, it is reasonable to assume that if the student adds both bicarbonate ion and hydrogen ion to the trial, the reaction will shift farther to the left than if the student had only added one of the reactants.
Example Question #213 : Chemistry
Enzymes (large molecules) serve to catalyze, or speed up, chemical reactions in the human body. This process of catalysis begins with the binding of a substrate (the reactant) to the active site of an enzyme. This active site is simply the portion of the enzyme that interacts with the substrate. Following the binding event, products separate from the enzyme active site, at which point the enzyme is prepared to undergo another reaction cycle. Two scientists offer conflicting views on the nature of the enzyme-substrate interaction.
Scientist 1
The enzyme-substrate interaction can be modeled with a Lock and Key paradigm. In this model, the enzyme represents a lock and the substrate represents a key. Only the substrate of proper size and shape will fit into a particular enzyme's active site and catalyze the reaction. The enzyme-substrate complex, the intermediate of this reaction, is stabilized mostly by strong ionic and hydrogen bonds. Following the formation of this intermediate, the enzyme changes the substrate in some way, leading to formation of a product, which subsequently dissociates from the enzyme.
Scientist 2
The shapes of substrate and enzyme are not exactly complementary. When it binds to the enzyme, the substrate induces the active site to alter its shape in order to enhance the fit. Thus, at first the interaction between substrate and enzyme is weak, but subsequent changes in the active site lead to stronger binding. Only the correct substrate will be able to modify the active site in the proper manner. Experimental data seems consistent with this Induced Fit model and inconsistent with the Lock and Key model.
In the following sequences, hyphens denote bound complexes and plus signs indicate separate species. Which of the sequences is consistent with the viewpoint of Scientist 1?
Enzyme+Substrate, Enzyme-Substrate, Enzyme+Product
Enzyme+Substrate, Enzyme-Substrate, Enzyme-Product, Enzyme+Product
Enzyme+Substrate, Enzyme+Product
Enzyme+Substrate, Enzyme-Product, Enzyme+Product
Enzyme+Substrate, Enzyme-Substrate, Enzyme-Product, Enzyme+Product
Scientist 1 explains that the substrate first binds to the enzyme to form an intermediate (the enzyme-substrate complex). While it is still bound to the enzyme, the substrate is then converted to product. Finally, the product dissociates from the enzyme.
Example Question #221 : Chemistry
Enzymes (large molecules) serve to catalyze, or speed up, chemical reactions in the human body. This process of catalysis begins with the binding of a substrate (the reactant) to the active site of an enzyme. This active site is simply the portion of the enzyme that interacts with the substrate. Following the binding event, products separate from the enzyme active site, at which point the enzyme is prepared to undergo another reaction cycle. Two scientists offer conflicting views on the nature of the enzyme-substrate interaction.
Scientist 1
The enzyme-substrate interaction can be modeled with a Lock and Key paradigm. In this model, the enzyme represents a lock and the substrate represents a key. Only the substrate of proper size and shape will fit into a particular enzyme's active site and catalyze the reaction. The enzyme-substrate complex, the intermediate of this reaction, is stabilized mostly by strong ionic and hydrogen bonds. Following the formation of this intermediate, the enzyme changes the substrate in some way, leading to formation of a product, which subsequently dissociates from the enzyme.
Scientist 2
The shapes of substrate and enzyme are not exactly complementary. When it binds to the enzyme, the substrate induces the active site to alter its shape in order to enhance the fit. Thus, at first the interaction between substrate and enzyme is weak, but subsequent changes in the active site lead to stronger binding. Only the correct substrate will be able to modify the active site in the proper manner. Experimental data seems consistent with this Induced Fit model and inconsistent with the Lock and Key model.
For a certain enzyme that is also a protein, it is observed that the amino acids (building blocks of a protein) near the active site move immediately after the substrate binds. Is this observation consistent with the viewpoint of Scientist 1?
Yes, because Scientist 1 would say that amino acids near the active site should move upon binding of substrate.
No, because Scientist 1 would say that amino acids near the active site should not move upon binding of substrate.
No, because Scientist 1 would say that amino acids near the active site should move upon binding of substrate.
Yes, because Scientist 1 would say that amino acids near the active site should not move upon binding of substrate.
No, because Scientist 1 would say that amino acids near the active site should not move upon binding of substrate.
The observation that the active site changes shape upon substrate binding is consistent with the Induced Fit model. Therefore, this observation is not consistent with the viewpoint of Scientist 1.
Example Question #222 : Chemistry
Enzymes (large molecules) serve to catalyze, or speed up, chemical reactions in the human body. This process of catalysis begins with the binding of a substrate (the reactant) to the active site of an enzyme. This active site is simply the portion of the enzyme that interacts with the substrate. Following the binding event, products separate from the enzyme active site, at which point the enzyme is prepared to undergo another reaction cycle. Two scientists offer conflicting views on the nature of the enzyme-substrate interaction.
Scientist 1
The enzyme-substrate interaction can be modeled with a Lock and Key paradigm. In this model, the enzyme represents a lock and the substrate represents a key. Only the substrate of proper size and shape will fit into a particular enzyme's active site and catalyze the reaction. The enzyme-substrate complex, the intermediate of this reaction, is stabilized mostly by strong ionic and hydrogen bonds. Following the formation of this intermediate, the enzyme changes the substrate in some way, leading to formation of a product, which subsequently dissociates from the enzyme.
Scientist 2
The shapes of substrate and enzyme are not exactly complementary. When it binds to the enzyme, the substrate induces the active site to alter its shape in order to enhance the fit. Thus, at first the interaction between substrate and enzyme is weak, but subsequent changes in the active site lead to stronger binding. Only the correct substrate will be able to modify the active site in the proper manner. Experimental data seems consistent with this Induced Fit model and inconsistent with the Lock and Key model.
With which of the following statements would both Scientist 1 and Scientist 2 most likely agree?
Substrates of various shapes can interact with a given enzyme to generate products.
A given enzyme can undergo the same reaction cycle more than once.
The enzyme-substrate complex is not stabilized.
Enzymes are typically small molecules.
A given enzyme can undergo the same reaction cycle more than once.
In the first paragraph, we are told that the enzyme is prepared to undergo another reaction cycle after product dissociates from it. This is general information about enzymes (not specific to either the Lock and Key model or Induced Fit model). Therefore, both scientists would probably agree with this statement.
Example Question #223 : Chemistry
Enzymes (large molecules) serve to catalyze, or speed up, chemical reactions in the human body. This process of catalysis begins with the binding of a substrate (the reactant) to the active site of an enzyme. This active site is simply the portion of the enzyme that interacts with the substrate. Following the binding event, products separate from the enzyme active site, at which point the enzyme is prepared to undergo another reaction cycle. Two scientists offer conflicting views on the nature of the enzyme-substrate interaction.
Scientist 1
The enzyme-substrate interaction can be modeled with a Lock and Key paradigm. In this model, the enzyme represents a lock and the substrate represents a key. Only the substrate of proper size and shape will fit into a particular enzyme's active site and catalyze the reaction. The enzyme-substrate complex, the intermediate of this reaction, is stabilized mostly by strong ionic and hydrogen bonds. Following the formation of this intermediate, the enzyme changes the substrate in some way, leading to formation of a product, which subsequently dissociates from the enzyme.
Scientist 2
The shapes of substrate and enzyme are not exactly complementary. When it binds to the enzyme, the substrate induces the active site to alter its shape in order to enhance the fit. Thus, at first the interaction between substrate and enzyme is weak, but subsequent changes in the active site lead to stronger binding. Only the correct substrate will be able to modify the active site in the proper manner. Experimental data seems consistent with this Induced Fit model and inconsistent with the Lock and Key model.
The active site of an enzyme has a volume of about 
The active site would not change.
The active site would expand.
The active site would expand and then shrink.
The active site would shrink.
The active site would shrink.
Scientist 2 believes that the shape of an active site changes to fit the substrate. Thus, if a substrate of known volume binds to an active site of larger volume, the active site must shrink to enhance the fit.
Example Question #901 : Act Science
The electrons of an atom surround the nucleus and reside in atomic orbitals. In transition metals such as iron (
Scientists perform a number of experiments to determine how various factors affect the magnitude of splitting. They find that the charge on the metal, the metal's position on the periodic table (whether it resides in Period 4, 5, or 6), and the identity of the ligand are all important factors. The scientists' results are summarized in Table 1. Note that a higher value of 
Table 1
Consider Table 1. Which of the following factors differed between Trial 1 and Trial 3?
The identity of the compound tested
The number of ligands tested
The position of the metal on the periodic table
The charge on the compound
The identity of the compound tested
If we compare the two trials (row 1 and row 3 of Table 1), we see that only the identity of the ligand changes. The scientists tested 
Example Question #21 : How To Find Research Summary In Chemistry
The electrons of an atom surround the nucleus and reside in atomic orbitals. In transition metals such as iron (
Scientists perform a number of experiments to determine how various factors affect the magnitude of splitting. They find that the charge on the metal, the metal's position on the periodic table (whether it resides in Period 4, 5, or 6), and the identity of the ligand are all important factors. The scientists' results are summarized in Table 1. Note that a higher value of 
Table 1
Which compounds illustrate the relationship between position of a metal on the periodic table and splitting magnitude?
Example Question #226 : Chemistry
The electrons of an atom surround the nucleus and reside in atomic orbitals. In transition metals such as iron (
Scientists perform a number of experiments to determine how various factors affect the magnitude of splitting. They find that the charge on the metal, the metal's position on the periodic table (whether it resides in Period 4, 5, or 6), and the identity of the ligand are all important factors. The scientists' results are summarized in Table 1. Note that a higher value of
Table 1
The coordination number of a compound refers to the number of ligands attached to the central metal atom (All compounds listed in Table 1 have coordination number of 6). Given that a lower coordination number tends to result in a smaller splitting magnitude, which of the following could be the splitting magnitude of 
Example Question #227 : Chemistry
Kevin wants to know if a particular kind of chemical fertilizer will help or hinder the growth of his tomato plants. He decides to conduct an experiment in which he grows three plants, one left untreated, one treated with the chemical fertilizer RapidGro and one treated with an organic compost. He records his findings in the charts below, measuring plant height and number of tomatoes over a period of time.
Height of plant (inches):
|
Day |
No Fertilizer |
RapidGro |
Compost |
|
1 |
3 |
3 |
3 |
|
2 |
5 |
6 |
4 |
|
3 |
7 |
9 |
6 |
|
4 |
9 |
12 |
8 |
|
7 |
15 |
21 |
14 |
|
10 |
16 |
21 |
19 |
|
14 |
18 |
18 |
21 |
Number of tomatoes:
|
Day |
No fertilizer |
RapidGro |
Compost |
|
1 |
0 |
0 |
0 |
|
2 |
1 |
2 |
1 |
|
3 |
1 |
3 |
2 |
|
4 |
2 |
4 |
3 |
|
7 |
4 |
7 |
5 |
|
10 |
6 |
7 |
6 |
|
14 |
6 |
4 |
7 |
On the fourteenth day Kevin picks the biggest tomato from each plant and record its dimensions, as well as other information, which is found below.
Tomato 1 (no fertilizer): 
Tomato 2 (RapidGro): 
Tomato 3 (compost): 
What might make it difficult for Kevin to draw a conclusion about the plants?
The use of two variables
The inconsistent days of data collection
The unscientific description of the tomatoes
All of these answers
All of these answers
Kevin has more than one variable (fertilizer and compost), as well as not collecting data every day and not being scientific in describing his results all make the experiment weaker.
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