Card 0 of 1617
Chemical reactions involve two main components, reactants and products. The reactants, often referred to as substrates, interact with each other and rearrange in order to be converted into products. The speeds of these reactions are often defined by substrate concentration and the presence of enzymes. Enzymes are referred to as catalysts. Peroxidase is traditionally derived from turnips; however, it is commonly found in many plant and animal cells. This enzyme helps plant cells by removing hydrogen peroxide from cells in the form of tetraguaiacol.
Study 1
A scientist wants to observe the production of tetraguaiacol by observing a reaction between hydrogen peroxide and guaiacol. The product of this reaction is orange-brown in color. The scientist measures the intensity of color in each sample using a spectrophotometer. In the control experiment, the scientist mixed the substrates together and measured the reaction rate. In the test experiment, a peroxidase enzyme was added to a new set of substrates and rate of reaction was measured. The results of these reactions are plotted in Figure 1.
Figure 1
Study 2
A research team decides to study the effects of the peroxidase facilitated reaction in the presence of heat. Reaction rates are known to speed up when heat is applied; however, at a certain point enzymes, such as peroxidase, denature and the reaction slows. The scientists perform a control trial at room temperature and test trials at
,
, and
. The results are plotted in Figure 2.
Figure 2
In Figure 1 of Study 1, why does the control reaction occur at a different rate than the enzyme reaction?
The control reaction occured slower because the enzyme catalyzes the reaction.
In the Study 1 reaction, the enzyme trial occurred at a far greater rate than the unassisted control trial. In the passage, there was evidence that enzymes catalyze and speed up reactions; therefore, this is the likely conclusion for the differences between trials in Study 1. There is no evidence that the enzyme provided a false positive and temperature was only varied in the Study 2 trials, which indicates that these choices are incorrect.
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Hydraulic fracturing (Fracking) is a process utilized to obtain natural gas from the ground. Operators drill deep down into fragile shale rock and pump a specialized mixture of chemical fluids into the well. The fluids increase the pressure inside the well and cause the shale to fracture. As the shale rocks fracture, fissures of natural gas are released from pockets within the earth. After the fluid has been pushed into the system, the natural gas is released through the drilled well and collected at the rig site on ground level. This fairly new and innovative process has yielded promising results and has created great controversy. Two scientists express their views on the hydraulic fracturing industry.
Study 1
A study was completed in order to measure the amount of methane released at an individual fracking rig. The scientist places an apparatus on the rig that measures the amount of methane released into the atmosphere in a 16-month period. The data is located in Figure 1.
Figure 1
Study 2
A researcher studies gaseous emissions in relation to global climate change. Global warming potential is the amount of energy that a gas absorbs over a 100-year period when compared to carbon dioxide. Through numerous studies, the researcher determines that methane has a global warming potential of 21 meaning that it will cause 21 times more warming over a 100-year period than an equivalent mass of carbon dioxide.
Local legislators are worried about methane emissions in their county. They consult Study 1 at the six-month mark of the investigation. They determine that the amount of methane released into the environment due to hydraulic fracturing is negligible, and their is no reason to be worried about future emissions. Is their conclusion valid given the evidence present in the passage?
No, the trend in the graph shows a near exponential rise in methane emissions after the six month mark.
This is the correct answer because it is clear that the methane levels spike after the rig has been in operation over six months. This increase is so great that it follows the shape of an exponential growth curve. No evidence in the passage supports that low levels of methane are hazardous. Likewise, no evidence states that levels below 16 metric tons in a month are safe. Last, before making a conclusion on the dangers of fracking, the legislators should study a site for more than six months.
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Hydraulic fracturing (Fracking) is a process utilized to obtain natural gas from the ground. Operators drill deep down into fragile shale rock and pump a specialized mixture of chemical fluids into the well. The fluids increase the pressure inside the well and cause the shale to fracture. As the shale rocks fracture, fissures of natural gas are released from pockets within the earth. After the fluid has been pushed into the system, the natural gas is released through the drilled well and collected at the rig site on ground level. This fairly new and innovative process has yielded promising results and has created great controversy. Two scientists express their views on the hydraulic fracturing industry.
Study 1
A study was completed in order to measure the amount of methane released at an individual fracking rig. The scientist places an apparatus on the rig that measures the amount of methane released into the atmosphere in a 16-month period. The data is located in Figure 1.
Figure 1
Study 2
A researcher studies gaseous emissions in relation to global climate change. Global warming potential is the amount of energy that a gas absorbs over a 100-year period when compared to carbon dioxide. Through numerous studies, the researcher determines that methane has a global warming potential of 21 meaning that it will cause 21 times more warming over a 100-year period than an equivalent mass of carbon dioxide.
Methane is released from the drilling site in both a gaseous and liquid form. The methane often permeates the mud of local aquatic biomes. A certain bacteria utilizes methane to produce oxygen and energy. What is expected to happen to this bacteria population in the time span between months 4 and 14 of Figure 1?
The bacterial colony will increase in number due to excess methane.
The population will grow in number because the increased amount of resources will increase the carrying capacity of the environment. The excess methane will allow the bacterial colony to grow in number. It will also help maintain this colony as long as appropriate levels of methane are produced and leaked into the mud of the aquatic biome.
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Basic conditions indicate that the optimal pH is greater than 7 (acidic conditions are less than 7). Enzyme B is most functional at pH 9, suggesting it works most efficienty in basic conditions.
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Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Yet, despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.
Scientist 1
During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (sleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (sleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.
Scientist 2
During waking hours, it is true that the body utilizes large amounts of energy. However, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules for future use during the next period of activity. Furthermore, sleep allows the body to repair cellular damages that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.
Both scientists give evidence to support their theories. The evidence given by Scientist 1 can best be described as __________.
Scientist 1 gives two examples of animals that appear to follow the trends of his theory. "For example, many herbivores, such as squirrels, are diurnal . . . while many insectivores, such as bats, are nocturnal"
This evidence is strictly observational. There is no experimental set-up, quantitative or empirical data. Though the evidence is observation of animals in their natural state, observational is a commonly used classification of evidence, while natural is not, making observational the best answer choice.
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Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Yet, despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.
Scientist 1
During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (sleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (sleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.
Scientist 2
During waking hours, it is true that the body utilizes large amounts of energy. However, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules for future use during the next period of activity. Furthermore, sleep allows the body to repair cellular damages that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.
Both scientists give evidence to support their theories. The evidence given by Scientist 2 can best be described as __________.
The evidence given by Scientist 2 is labeled within the passage. "Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase"
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Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics. Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd)
A study was done in which the visual traits of two plants and their offspring was tested. In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant. In previous generations Plant A’s parents were always tall but were sometimes pink. Plant B’s parents were sometimes tall or short and sometimes were pink or purple. It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P).
Breeding both plants will result in offspring that have recessive and dominant traits. The chart below contains all the possibilities for their offspring.
Figure 1.
Parent A | Parent B |
---|---|
Tall (HH) | Tall (Hh) |
Purple (Pp) | Pink (pp) |
Figure 2. HH Pp x Hh pp Offspring
| | HP | HP | Hp | Hp | | | --------- | ------ | ------ | ------ | ---- | | Hp | HHPp | HHPp | HHpp | HHpp | | Hp | HHPp | HHPp | HHpp | HHpp | | hp | HhPp | HhPp | Hhpp | Hhpp | | hp | HhPp | HhPp | Hhpp | Hhpp |
What traits would an offspring have with hh PP alleles?
The plant will be short and purple. Since hh are both recessive, there are no dominant genes to make the plant tall; thus the plant will be short. Since P is dominant, the plant must be purple since it has both dominant genes.
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Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics. Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd)
A study was done in which the visual traits of two plants and their offspring was tested. In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant. In previous generations Plant A’s parents were always tall but were sometimes pink. Plant B’s parents were sometimes tall or short and sometimes were pink or purple. It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P).
Breeding both plants will result in offspring that have recessive and dominant traits. The chart below contains all the possibilities for their offspring.
Figure 1.
Parent A | Parent B |
---|---|
Tall (HH) | Tall (Hh) |
Purple (Pp) | Pink (pp) |
Figure 2. HH Pp x Hh pp Offspring
| | HP | HP | Hp | Hp | | | --------- | ------ | ------ | ------ | ---- | | Hp | HHPp | HHPp | HHpp | HHpp | | Hp | HHPp | HHPp | HHpp | HHpp | | hp | HhPp | HhPp | Hhpp | Hhpp | | hp | HhPp | HhPp | Hhpp | Hhpp |
What is the probability that the offspring in Figure 2 will be tall and purple?
The sets of alleles that are labeled HHPp or HhPp are the only possibilities to have a plant that is tall and purple. Since 8 out of the 16 possibilities are of such, there is a 50% probability.
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Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics. Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd)
A study was done in which the visual traits of two plants and their offspring was tested. In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant. In previous generations Plant A’s parents were always tall but were sometimes pink. Plant B’s parents were sometimes tall or short and sometimes were pink or purple. It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P).
Breeding both plants will result in offspring that have recessive and dominant traits. The chart below contains all the possibilities for their offspring.
Figure 1.
Parent A | Parent B |
---|---|
Tall (HH) | Tall (Hh) |
Purple (Pp) | Pink (pp) |
Figure 2. HH Pp x Hh pp Offspring
| | HP | HP | Hp | Hp | | | --------- | ------ | ------ | ------ | ---- | | Hp | HHPp | HHPp | HHpp | HHpp | | Hp | HHPp | HHPp | HHpp | HHpp | | hp | HhPp | HhPp | Hhpp | Hhpp | | hp | HhPp | HhPp | Hhpp | Hhpp |
What is the ratio of pink plants to purple plants?
The ratio of pink to purple is 1 : 1. There are just as many pink (8pp) to purple (8Pp). Thus when reduced, 8 : 8 turns to 1 : 1.
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Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics. Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd)
A study was done in which the visual traits of two plants and their offspring was tested. In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant. It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P).
Breeding both plants will result in offspring that have recessive and dominant traits. The chart below contains all the possibilities for their offspring.
Figure 1.
Parent A | Parent B |
---|---|
Tall (HH) | Tall (Hh) |
Purple (Pp) | Pink (pp) |
Figure 2. HH Pp x Hh pp Offspring
| | HP | HP | Hp | Hp | | | --------- | ------ | ------ | ------ | ---- | | Hp | HHPp | HHPp | HHpp | HHpp | | Hp | HHPp | HHPp | HHpp | HHpp | | hp | HhPp | HhPp | Hhpp | Hhpp | | hp | HhPp | HhPp | Hhpp | Hhpp |
Why are there no short offspring?
The answer is Parent A has two dominant genes, it can only pass down dominant genes to its offspring. No matter what parent A can do, it can only give a dominant allele that makes the offspring shows a tall trait.
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A group of scientists wanted to test the effects of Nitra-Grow, a chemical additive that can be given to plants to help them grow. 3 test groups of plants were given all the same time of sunlight, the same type of soil, and the same amount of water. Plant A was given no extra chemicals. Plant B was given 5g of Nitra-Grow. Plant C was given 5g of Ammonia to see if Nitra-Grow worked any better than a basic nitrogen-based household product. The plants are then measured on 5 consecutive days to find their average height (in cm).
DAY | Height Plant A (cm) | Height Plant B (cm) | Height Plant C (cm) |
---|---|---|---|
1 | 1.2 | 1.2 | 1.2 |
2 | 1.4 | 1.4 | 1.2 |
3 | 1.6 | 1.8 | 1.3 |
4 | 1.8 | 2.4 | 1.3 |
5 | 2.0 | 2.6 | 1.4 |
Suppose on day 6, here are the results of each of the 3 plants.
Plant A | Plant B | Plant C |
---|---|---|
2.2 | 1.5 | 1.4 |
What could you say about the effectiveness of Nitra-Grow?
The answer is Nitro-Grow is not effective. Even though the plants increased in height until day 5, there was a drastic decrease on day 6. The chemical is NOT effective because day 6 shows that Plant B has wilted away and is decreasing in size.
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A group of scientists wanted to test the effects of Nitra-Grow, a chemical additive that can be given to plants to help them grow. 3 test groups of plants were given all the same time of sunlight, the same type of soil, and the same amount of water. Plant A was given no extra chemicals. Plant B was given 5g of Nitra-Grow. Plant C was given 5g of Ammonia to see if Nitra-Grow worked any better than a basic nitrogen-based household product. The plants are then measured on 5 consecutive days to find their average height (in cm).
DAY | Height Plant A (cm) | Height Plant B (cm) | Height Plant C (cm) |
---|---|---|---|
1 | 1.2 | 1.2 | 1.2 |
2 | 1.4 | 1.4 | 1.2 |
3 | 1.6 | 1.8 | 1.3 |
4 | 1.8 | 2.4 | 1.3 |
5 | 2.0 | 2.6 | 1.4 |
Suppose that the scientists repeated the experiment with Plant D. Plant D was given 15g of Nitro-Grow and 15g of Ammonia. What would be the expected results?
There is not enough information. You cannot assume it will perform the best because ultimately, negative effects were proven for Ammonia. There is no study on the combination of effects for both chemicals.
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A group of scientists wanted to test the effects of Nitra-Grow, a chemical additive that can be given to plants to help them grow. 3 test groups of plants were given all the same time of sunlight, the same type of soil, and the same amount of water. Plant A was given no extra chemicals. Plant B was given 5g of Nitra-Grow. Plant C was given 5g of Ammonia to see if Nitra-Grow worked any better than a basic nitrogen-based household product. The plants are then measured on 5 consecutive days to find their average height (in cm).
DAY | Height Plant A (cm) | Height Plant B (cm) | Height Plant C (cm) |
---|---|---|---|
1 | 1.2 | 1.2 | 1.2 |
2 | 1.4 | 1.4 | 1.2 |
3 | 1.6 | 1.8 | 1.3 |
4 | 1.8 | 2.4 | 1.3 |
5 | 2.0 | 2.6 | 1.4 |
What is the general relationship between plant height and the amount of days?
As time increases, the heights of all plants increase (except for plant B on day 6). The day doesn't change just because the plants grow.
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The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
Based on the chart above, which plant species was consistently taller than the other plant species regardless of soil medium?
After reading the chart, it is clear that Plant 3 was taller than Plant 1 and Plant 2 at every measurement point.
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The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
Which soil medium provides the tallest plant growth?
The medium providing the tallest plant growth would be medium D, because in all three plants reached their greatest height using medium D.
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The significant increase in atmospheric carbon dioxide since pre-industrial levels can be seen in the world’s oceans which absorb the CO2 and in turn undergo changes in chemistry. The consequences of increased CO2 include acidification of seawater and a decrease in carbonate ion (CO32-) concentration.
Changes in seawater chemistry affect marine organisms. The early life stages of invertebrates, such as squid, may be particularly vulnerable to changes in carbon dioxide levels. Acting as both predator and prey, squid are a significant component of marine ecosystems. For example, fish and sea birds, such as tuna and albatross, are dependent on squid as a source of prey. Furthermore, the fishing industry is impacted by the health of squid populations. California fisheries produce the majority of market squid.
In order to determine how increased levels of carbon dioxide affect the development of squid, eggs were hatched in two different conditions: normal (380 µatm) and elevated (2100 µatm) levels of CO2. The time to hatch and the size of the larval mantle (the anatomical feature that includes the body wall and fins) were measured and recorded. Two trials were conducted for each carbon dioxide concentration.
According to the passage, which of these are most directly affected by changes in marine carbon dioxide levels?
Although the passage indicates that humans, fish and seabirds are all impacted by the health of squid populations, the squid themselves are directly impacted by marine carbon dioxide levels: "The early life stages of invertebrates, such as squid, may be particularly vulnerable to changes in carbon dioxide levels."
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The significant increase in atmospheric carbon dioxide since pre-industrial levels can be seen in the world’s oceans which absorb the CO2 and in turn undergo changes in chemistry. The consequences of increased CO2 include acidification of seawater and a decrease in carbonate ion (CO32-) concentration.
Changes in seawater chemistry affect marine organisms. The early life stages of invertebrates, such as squid, may be particularly vulnerable to changes in carbon dioxide levels. Acting as both predator and prey, squid are a significant component of marine ecosystems. For example, fish and sea birds, such as tuna and albatross, are dependent on squid as a source of prey. Furthermore, the fishing industry is impacted by the health of squid populations. California fisheries produce the majority of market squid.
In order to determine how increased levels of carbon dioxide affect the development of squid, eggs were hatched in two different conditions: normal (380 µatm) and elevated (2100 µatm) levels of CO2. The time to hatch and the size of the larval mantle (the anatomical feature that includes the body wall and fins) were measured and recorded. Two trials were conducted for each carbon dioxide concentration.
In this experiment, which of the following most likely affects squid-egg hatching?
The data shows that carbon dioxide concentration affects egg hatching. The task is to identify which variable correlates with carbon dioxide concentration. Looking at the water chemistry table, it is clear that pH is the only measurement that varies between CO2 concentrations. (Salinity and temperature are similar, and the amount of water is not mentioned.)
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Genes are hereditary units that are responsible for the phenotypes of an organism. Genes are the directions for the body. Genetic change exists when genes are altered from their previous form. Genes are made up of DNA, or deoxyribonucleic acid. DNA is made up of four bases- adenine, guanine, cytosine, and thymine. Genetic change can result from a variety of factors. Both scientists mentioned below agree on this basic information about genes. However, the scientists do not agree on the primary driving force behind genetic change.
Scientist 1
A mutation is a permanent change in the sequence of the DNA of a gene. There are several types of mutations—point mutations, silent mutations, frame mutations, and nonsense mutations. Mutations are very important because proteins are synthesized by reading the DNA sequence. If the DNA sequence is changed, the proteins transcribed from the DNA will be different proteins. Mutations directly and substantially change the genes by changing the sequence of the four bases. Therefore, mutations are the main factor when looking at genetic change.
Scientist 2
Sexual reproduction is the biggest contributor to genetic change. New combinations of genes are created with every random union of a sperm and egg. During division of the sex cells, or meiosis, crossing over can occur. Crossing over describes the situation when the genes from one parent’s chromosome are traded with genes from the other parent’s chromosome. This results in new combinations of genes. Lastly, a phenomenon called independent assortment results from sexual reproduction. Independent assortment is the random assortment of chromosomes during reproduction. Therefore, by its random nature, sexual reproduction is the largest contributor to genetic change.
When Scientist 1 states that mutations "change the genes by changing the sequence of the four bases," the word "bases" is referring to what?
Paragraph one lists the four bases as adenine, guanine, cytosine, and thymine.
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The vertex for Enzyme A occurs at 45 degrees C and pH 5 indicated these are the optimal conditions for the enzyme to function.
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