ACT Science : Biology

Study concepts, example questions & explanations for ACT Science

varsity tutors app store varsity tutors android store varsity tutors amazon store varsity tutors ibooks store

Example Questions

Example Question #621 : Biology

Before modern technologies and experiments allowed scientists to understand different organisms' mechanisms of reproduction, numerous theories existed about how populations came to exist. Two scientists from the 1800s describe their theories. Here are their arguments.

Scientist I

Just like some plants come from seeds and others are capable of vegetative (asexual) reproduction, some animal organisms come from non-sexual reproduction as well. Maggots, for example, appear on rotting carcasses. It is clearly illogical to suggest that the dead animal created or gave birth to the maggots, as it is no longer alive and is therefore incapable of sexual reproduction. The only rational conclusion for the appearance of maggots is a spontaneous generation. This is similar to how, if one were to leave a bowl of broth in the open air for a week, it would turn cloudy from bacteria appearing in the liquid.

Scientist II

Animate objects cannot arise from inanimate objects. Even when plants perform asexual reproduction, daughter plants are still coming from parent plants. There is no other example in nature of a living organism spontaneously coming into being. It is true that we observe maggots on rotting carcasses, but that does not necessarily mean that the maggots came from the rotting carcass. Similarly, bacteria growing in broth do not necessarily come directly from the broth. If a living organism appears, then it must have come from another animate object, even if we did not witness it. It is more likely that these invisible organisms have come in through the air and we simply do not see them until they have had a chance to replicate in these locations.

Which of the following experiments might a third scientist perform to see which of these two theories is correct?

Possible Answers:

Leave the refrigerator open indefinitely and observe the molds that appear

Seal off a liter of broth so that no air can get in, then observe the changes when the seal is broken and air can enter

Leave a piece of meat unattended for several days, then return and observe

Leave broth under a heatlamp to observe if temperature affects bacterial growth

Correct answer:

Seal off a liter of broth so that no air can get in, then observe the changes when the seal is broken and air can enter

Explanation:

The two scientists disagree on if organisms can appear spontaneously. If a sealed container were observed and life appeared, it would disprove Scientist II and support Scientist I. Once the seal is broken, if life appears it would support Scientist II.

Example Question #622 : Biology

Before modern technologies and experiments allowed scientists to understand different organisms' mechanisms of reproduction, numerous theories existed about how populations came to exist. Two scientists from the 1800s describe their theories. Here are their arguments.

Scientist I

Just like some plants come from seeds and others are capable of vegetative (asexual) reproduction, some animal organisms come from non-sexual reproduction as well. Maggots, for example, appear on rotting carcasses. It is clearly illogical to suggest that the dead animal created or gave birth to the maggots, as it is no longer alive and is therefore incapable of sexual reproduction. The only rational conclusion for the appearance of maggots is a spontaneous generation. This is similar to how, if one were to leave a bowl of broth in the open air for a week, it would turn cloudy from bacteria appearing in the liquid.

Scientist II

Animate objects cannot arise from inanimate objects. Even when plants perform asexual reproduction, daughter plants are still coming from parent plants. There is no other example in nature of a living organism spontaneously coming into being. It is true that we observe maggots on rotting carcasses, but that does not necessarily mean that the maggots came from the rotting carcass. Similarly, bacteria growing in broth do not necessarily come directly from the broth. If a living organism appears, then it must have come from another animate object, even if we did not witness it. It is more likely that these invisible organisms have come in through the air and we simply do not see them until they have had a chance to replicate in these locations.

Vitruvius, an ancient Roman architect, wrote that libraries should not be placed facing south or west, as those winds generated bookworms. Which theory did he support?

Possible Answers:

Neither theory is supported

Both theories are supported

Scientist I

Scientist II

Correct answer:

Scientist I

Explanation:

Scientist I argues for spontaneous generation. He would agree that the combination of Western light and paper could potentially form bookworms.

Scientist II would argue that the direction of the light is completely irrelevant to the reproduction of bookworms, as an original parent specimen is required to produce offspring.

Example Question #623 : Biology

Before modern technologies and experiments allowed scientists to understand different organisms' mechanisms of reproduction, numerous theories existed about how populations came to exist. Two scientists from the 1800s describe their theories. Here are their arguments.

Scientist I

Just like some plants come from seeds and others are capable of vegetative (asexual) reproduction, some animal organisms come from non-sexual reproduction as well. Maggots, for example, appear on rotting carcasses. It is clearly illogical to suggest that the dead animal created or gave birth to the maggots, as it is no longer alive and is therefore incapable of sexual reproduction. The only rational conclusion for the appearance of maggots is a spontaneous generation. This is similar to how, if one were to leave a bowl of broth in the open air for a week, it would turn cloudy from bacteria appearing in the liquid.

Scientist II

Animate objects cannot arise from inanimate objects. Even when plants perform asexual reproduction, daughter plants are still coming from parent plants. There is no other example in nature of a living organism spontaneously coming into being. It is true that we observe maggots on rotting carcasses, but that does not necessarily mean that the maggots came from the rotting carcass. Similarly, bacteria growing in broth do not necessarily come directly from the broth. If a living organism appears, then it must have come from another animate object, even if we did not witness it. It is more likely that these invisible organisms have come in through the air and we simply do not see them until they have had a chance to replicate in these locations.

How might Scientist II respond to Scientist I's arguments about asexual reproduction?

Possible Answers:

Scientist II would agree with this point, as it proves his theory

Even though the reproduction is asexual, a living organism is still "giving birth" to a living organism

Sexual reproduction has a greater chance of multiple offspring

There is nothing similar between plants and animals

Correct answer:

Even though the reproduction is asexual, a living organism is still "giving birth" to a living organism

Explanation:

Scientist II argues that living organisms give birth to living organisms, and that life cannot come from inanimate matter. The answer choice that most closely matches this hypothesis will be correct. Scientist II most closely believes that the most important factor is that life will be generated from life, no matter the method of reproduction.

Example Question #624 : Biology

Before modern technologies and experiments allowed scientists to understand different organisms' mechanisms of reproduction, numerous theories existed about how populations came to exist. Two scientists from the 1800s describe their theories. Here are their arguments.

Scientist I

Just like some plants come from seeds and others are capable of vegetative (asexual) reproduction, some animal organisms come from non-sexual reproduction as well. Maggots, for example, appear on rotting carcasses. It is clearly illogical to suggest that the dead animal created or gave birth to the maggots, as it is no longer alive and is therefore incapable of sexual reproduction. The only rational conclusion for the appearance of maggots is a spontaneous generation. This is similar to how, if one were to leave a bowl of broth in the open air for a week, it would turn cloudy from bacteria appearing in the liquid.

Scientist II

Animate objects cannot arise from inanimate objects. Even when plants perform asexual reproduction, daughter plants are still coming from parent plants. There is no other example in nature of a living organism spontaneously coming into being. It is true that we observe maggots on rotting carcasses, but that does not necessarily mean that the maggots came from the rotting carcass. Similarly, bacteria growing in broth do not necessarily come directly from the broth. If a living organism appears, then it must have come from another animate object, even if we did not witness it. It is more likely that these invisible organisms have come in through the air and we simply do not see them until they have had a chance to replicate in these locations.

An experiment is performed in which a bowl of broth containing bacteria is boiled and then left in the open air. After a day, the broth is observed to be cloudy. How might Scientist II explain this result?

Possible Answers:

Broth is the preferred spawning ground of bacteria

The bacteria spontaneously appeared under the right circumstances

The bacteria may have replicated in the broth, but it did not originate in there

Broth should not turn cloudy and an error was made during the experiment

Correct answer:

The bacteria may have replicated in the broth, but it did not originate in there

Explanation:

Scientist II believes that an animate object must come from an animate object, therefore it could not have been spontaneously created. Some original specimen must have entered the broth, allowing for reproduction.

He does not discuss the preferred reproductive locations of bacteria, nor would he argue that the experiment was not conducted correctly.

Example Question #625 : Biology

Scientist 1

In any population wherein some individuals are susceptible to a given disease, the prevalence of that disease is as much determined by the fraction of the population that is immune as by other environmental factors. If the majority of members in a community are immune, even those who are still susceptible are afforded some degree of protection by herd immunity. The spread of disease is limited by the creation of a large immune population, which benefits the entire community. This is why it is so important to immunize as many people as possible against dangerous contagious diseases, as it protects not only those who have been immunized, but those who have not.

Scientist 2

It is true that immunizing individuals provides some protection against contagious diseases, but the value of "herd immunity" has been overblown. The threshold at which a large enough proportion of the population has been immunized so that contagions cannot spread—the herd immunity threshold—depends on the virulence of the particular disease, as well as the effectiveness of the vaccine and the parameters of contagion. It is much easier to immunize a population against a disease that is only spread through blood-to-blood contact than against one that is airborne; thus, the usefulness of the herd immunity phenomenon is so limited that it is basically negligible. Instead of focusing on immunizing some percentage of the population in the hopes of reaching the herd immunity threshold, we should increase our efforts to limit the spread of various diseases through proper hygiene procedures and limiting contact with high-risk sources.

On which of the following statements would Scientist 1 and Scientist 2 likely agree?

Possible Answers:

All diseases can be prevented through proper hygiene procedures and avoiding high-risk sources.

In some situations, if a high enough percentage of the population were immunized against some contagious disease, the disease would be unable to spread.

Herd immunity is more important than hygiene procedures to prevent the spread of contagions.

The proportion of a population that must be immunized before the population can benefit from herd immunity is unrealistically high.

It would be easy to immunize against a disease that is spread through blood-to-blood contact.

Correct answer:

In some situations, if a high enough percentage of the population were immunized against some contagious disease, the disease would be unable to spread.

Explanation:

Scientist 1 and Scientist 2 disagree about whether herd immunity is the most reliable form of contagious disease prevention, but both scientists admit that herd immunity has some merits. Scientist 1 argues that herd immunity is a realistic means of controlling infectious diseases. Scientist 2 argues that the herd immunity threshold is too high to make herd immunity practical. Both scientists agree that if the herd immunity threshold is reached, then herd immunity can limit the spread of disease.

Neither scientist argues that herd immunity is more important than hygiene procedures. Only Scientist 2 argues that the herd immunity threshold is unrealistically high and that diseases should be prevented by more attention to environmental control factors. Scientist 2 also argues that diseases transferred by blood would be easier to counter with immunization.

Example Question #626 : Biology

Scientist 1

In any population wherein some individuals are susceptible to a given disease, the prevalence of that disease is as much determined by the fraction of the population that is immune as by other environmental factors. If the majority of members in a community are immune, even those who are still susceptible are afforded some degree of protection by herd immunity. The spread of disease is limited by the creation of a large immune population, which benefits the entire community. This is why it is so important to immunize as many people as possible against dangerous contagious diseases, as it protects not only those who have been immunized, but those who have not.

Scientist 2

It is true that immunizing individuals provides some protection against contagious diseases, but the value of "herd immunity" has been overblown. The threshold at which a large enough proportion of the population has been immunized so that contagions cannot spread—the herd immunity threshold—depends on the virulence of the particular disease, as well as the effectiveness of the vaccine and the parameters of contagion. It is much easier to immunize a population against a disease that is only spread through blood-to-blood contact than against one that is airborne; thus, the usefulness of the herd immunity phenomenon is so limited that it is basically negligible. Instead of focusing on immunizing some percentage of the population in the hopes of reaching the herd immunity threshold, we should increase our efforts to limit the spread of various diseases through proper hygiene procedures and limiting contact with high-risk sources.

Scientist 1 would most likely disagree with which of the following?

Possible Answers:

Non-contagious diseases, such as those caused purely by genetics, would not be preventable through herd immunity.

All diseases have a relatively low herd immunity threshold.

The effectiveness of herd immunity depends on the proportion of the population that has been immunized.

Environmental factors play a significant role in the prevalence of disease.

The herd immunity threshold will always be over half of the individuals in the population

Correct answer:

All diseases have a relatively low herd immunity threshold.

Explanation:

Scientist 1 asserts that herd immunity can be an effective tool in controlling the spread of contagious diseases, but does not claim that all diseases have a low herd immunity threshold. Scientist 1 argues for herd immunity as a means of combatting contagious diseases. Non-contagious diseases, such as genetic disorders, will not be affected by herd immunity. Also, specific attributes of a certain disease may increase its virulence, leading to a high herd immunity threshold. Scientist 1 does not argue that all diseases will have low thresholds, and would likely disagree with this statement.

The other answer options are all implied by Scientist 1's argument. He states that proportional immunity is as important "as other environmental factors" in determining overall prevalence, which suggests that environmental factors do play a significant role. He also states that "a majority" of a population would need to be immunized in order to achieve herd immunity; thus, any herd immunity threshold would be over half of the population.

Example Question #625 : Biology

Scientist 1

In any population wherein some individuals are susceptible to a given disease, the prevalence of that disease is as much determined by the fraction of the population that is immune as by other environmental factors. If the majority of members in a community are immune, even those who are still susceptible are afforded some degree of protection by herd immunity. The spread of disease is limited by the creation of a large immune population, which benefits the entire community. This is why it is so important to immunize as many people as possible against dangerous contagious diseases, as it protects not only those who have been immunized, but those who have not.

Scientist 2

It is true that immunizing individuals provides some protection against contagious diseases, but the value of "herd immunity" has been overblown. The threshold at which a large enough proportion of the population has been immunized so that contagions cannot spread—the herd immunity threshold—depends on the virulence of the particular disease, as well as the effectiveness of the vaccine and the parameters of contagion. It is much easier to immunize a population against a disease that is only spread through blood-to-blood contact than against one that is airborne; thus, the usefulness of the herd immunity phenomenon is so limited that it is basically negligible. Instead of focusing on immunizing some percentage of the population in the hopes of reaching the herd immunity threshold, we should increase our efforts to limit the spread of various diseases through proper hygiene procedures and limiting contact with high-risk sources.

Suppose that an extremely virulent bloodborne disease had spread rapidly through a population in which over 75% of the population had been immunized. What effects would this scenario have on each scientist's argument?

Possible Answers:

This supports Scientist 1's argument and does not detract from Scientist 2's argument.

This weakens both scientists' arguments

This supports Scientist 2's argument and does not detract from Scientist 1's argument.

This weakens Scientist 2's argument and supports Scientist 1's argument

This weakens Scientist 1's argument and supports Scientist 2's argument

Correct answer:

This supports Scientist 2's argument and does not detract from Scientist 1's argument.

Explanation:

Neither Scientist 1, nor Scientist 2 claimed that an extremely virulent disease would be absolutely stymied by herd immunity.

Scientist 2 claims that herd immunity thresholds for certain diseases might be so high that relying on herd immunity would not be effective. The case described supports that argument.

Scientist 1 never claimed that herd immunity would be absolutely effective against all diseases, nor did he mention a specific threshold at which a population would be safe from the spread of contagions. This case neither supports, nor undermines Scientist 1's argument.

Example Question #626 : Biology

Scientist 1

In any population wherein some individuals are susceptible to a given disease, the prevalence of that disease is as much determined by the fraction of the population that is immune as by other environmental factors. If the majority of members in a community are immune, even those who are still susceptible are afforded some degree of protection by herd immunity. The spread of disease is limited by the creation of a large immune population, which benefits the entire community. This is why it is so important to immunize as many people as possible against dangerous contagious diseases, as it protects not only those who have been immunized, but those who have not.

Scientist 2

It is true that immunizing individuals provides some protection against contagious diseases, but the value of "herd immunity" has been overblown. The threshold at which a large enough proportion of the population has been immunized so that contagions cannot spread—the herd immunity threshold—depends on the virulence of the particular disease, as well as the effectiveness of the vaccine and the parameters of contagion. It is much easier to immunize a population against a disease that is only spread through blood-to-blood contact than against one that is airborne; thus, the usefulness of the herd immunity phenomenon is so limited that it is basically negligible. Instead of focusing on immunizing some percentage of the population in the hopes of reaching the herd immunity threshold, we should increase our efforts to limit the spread of various diseases through proper hygiene procedures and limiting contact with high-risk sources.

Which of the following might Scientist 1 bring to Scientist 2's attention in order to convince him to change position?

Possible Answers:

Although many diseases have an unattainably high herd immunity thresholds, several of the most common diseases have low thresholds.

It would be significantly easier and more cost-effective to implement an immunization program than teach everyone in a population proper hygiene procedures.

Herd immunity has been thoroughly proven in the scientific community.

Environmental factors are unlikely to play an important role in the spread of contagious disease.

Airborne diseases are harder to prevent through hygiene than diseases that are spread through blood-to-blood contact.

Correct answer:

Although many diseases have an unattainably high herd immunity thresholds, several of the most common diseases have low thresholds.

Explanation:

In order for Scientist 1 to convince Scientist 2 to change his position, Scientist 1 needs to show some reason to believe that implementing an immunization strategy would effectively prevent the spread of disease. Scientist 2 is skeptical that prevention would be possible because many diseases have high herd immunity thresholds. If Scientist 1 could show that the most common diseases have low herd immunity thresholds, then Scientist 2 might be convinced that immunization could be effective at preventing the spread of disease.

The other answer choices either do not support Scientist 1's position or actually undermine it.

Example Question #627 : Biology

Scientist 1

In any population wherein some individuals are susceptible to a given disease, the prevalence of that disease is as much determined by the fraction of the population that is immune as by other environmental factors. If the majority of members in a community are immune, even those who are still susceptible are afforded some degree of protection by herd immunity. The spread of disease is limited by the creation of a large immune population, which benefits the entire community. This is why it is so important to immunize as many people as possible against dangerous contagious diseases, as it protects not only those who have been immunized, but those who have not.

Scientist 2

It is true that immunizing individuals provides some protection against contagious diseases, but the value of "herd immunity" has been overblown. The threshold at which a large enough proportion of the population has been immunized so that contagions cannot spread—the herd immunity threshold—depends on the virulence of the particular disease, as well as the effectiveness of the vaccine and the parameters of contagion. It is much easier to immunize a population against a disease that is only spread through blood-to-blood contact than against one that is airborne; thus, the usefulness of the herd immunity phenomenon is so limited that it is basically negligible. Instead of focusing on immunizing some percentage of the population in the hopes of reaching the herd immunity threshold, we should increase our efforts to limit the spread of various diseases through proper hygiene procedures and limiting contact with high-risk sources.

How would you describe Scientist 2's position on the effectiveness of herd immunity, compared Scientist 1's position on that subject?

Possible Answers:

Thoughtful versus reckless

Pessimistic versus hopeful

Ambiguous versus appealing

General versus specific

Cautious versus convinced

Correct answer:

Cautious versus convinced

Explanation:

The question asks for Scientist 2 compared to Scientist 1, meaning that the first adjective refers to Scientist 2 and the second refers to Scientist 1.

Scientist 2 does not entirely discount the possible effectiveness of herd immunity, but advises caution when considering it as a useful option for disease prevention. Scientist 1, on the other hand, sounds convinced that herd immunity is definitely capable of preventing the spread of contagious disease, and urges the audience to take action to that end.

The other answer choices do not provide accurate descriptions of the arguments.

Example Question #630 : Biology

     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.

 Enzyme_vs_control

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.

Test_1-3

Figure 2

Which of the following theories would the scientist in Study 2 most likely support?

Possible Answers:

Exercise is detrimental because it slightly raises bodily temperatures and slows enzyme productivity.

Fevers are dangerous because increased bodily temperatures can negatively effect enzyme activities.

Exposure to cold weather is beneficial because it helps to speed up enzyme reactions.

Temperature has little to no effect upon enzyme activities.

Correct answer:

Fevers are dangerous because increased bodily temperatures can negatively effect enzyme activities.

Explanation:

Fevers are dangerous because increased bodily temperatures can negatively effect enzyme activities.

The scientist in Study 2 would agree with this theory because it relates to his results. The scientist found that heat increased reaction rates to the point that the enzyme denatured and lost its function. The other answers are incorrect because they either state the inverse of this action or claim that temperature has no effect on enzyme reaction rates.

Learning Tools by Varsity Tutors