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 #661 : Biology

Vaccinations have become a controversial topic in the United States. Currently the US Food and Drug Administration (FDA) regulates all vaccines. The federal government does not mandate vaccinations for any individual; however, all states require vaccinations for children entering public school. There are several types of vaccines—live attenuated vaccines, inactivated vaccines, subunit vaccines, toxoid vaccines, and conjugate vaccines, just to name a few. All of these vaccines have the shared purpose of exposing the host body to antigens of a specific disease. When the body receives the antigens, the immune system is activated, remembering the antigens. The next time the individual is exposed to the disease, the body will remember the antigen and have a better probability of not getting infected. Two scientists below discuss their belief on vaccines.

Scientist 1

Vaccines have saved many lives. The risks of not being vaccinated far outweigh the risks of adverse vaccine reactions. Reports linking autism to vaccines have been evaluated by the CDC, which states there is no scientific link between autism and vaccines. The second leading cancer killer in women is cervical cancer. The HPV vaccine protects against the two most common strains causing cancer. This is an example of a vaccine that does much more good than bad. Vaccines also reduce the amount of money spent on healthcare, because the preventative cost of a vaccine is much cheaper than the cost of treating an infected person. The only time a vaccine should not be administered is if the chance of the individual coming into contact with the disease is so rare it is not worth the potential of adverse reactions.

 Scientist 2

Many vaccines nowadays are extraneous. Vaccines for diseases like whooping cough and scarlet fever were once necessary but now outdated. Modern updates on hygiene, waste management, and water filtration have resulted in significantly decreased chances of infection. In addition, diseases like rotavirus have an infection period of a few days, and the main symptom is dehydration. Modern medicine can easily treat severe dehydration, and the risk of rotavirus infection is very slim; therefore, the results of infection are far milder than the results of an adverse reaction. Vaccines for children can cause extremely dangerous adverse reactions. This includes anaphylactic shock, paralysis, and death. While scientists have not been able to conclusively prove this, many believe that these reactions are related to the age of the host and the lack of a developed immune systemor neural network. Vaccines suppress the immune system, which can lead to autoimmune disorders. In addition, vaccines can congest the lymphatic system with proteins molecules from the vaccines; therefore, I would recommend requirements for vaccination to take place at a later stage in a child’s development.

What biological reactions does Scientist 2 mention as negative results of vaccination

Possible Answers:

paralysis 

congest the lymphatic system 

all of the choices listed

anaphylatic shock

autoimmune diseases

Correct answer:

all of the choices listed

Explanation:

Scientist 2 states that "vaccines for children can cause extremely dangerous adverse reactions. This includes anaphylactic shock, paralysis, and death." Scientist 2 also mentions that "vaccines can congest the lymphatic system with protein molecules from the vaccines." Lastly he also states that "vaccines suppress the immune system, which can lead to autoimmune disorders."

Example Question #661 : Biology

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. 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 to 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.

Scientist 1’s theory would be most weakened if which of the following were true?

Possible Answers:

Desert animals often spend long periods sleeping during the day.

Sharks continue to move constantly while sleeping.

When deprived of sleep, chimpanzees require more food.

Some herbivores are diurnal, while others are nocturnal.

Bees sleep less during spring, when food is abundant.

Correct answer:

Sharks continue to move constantly while sleeping.

Explanation:

The answer is "Sharks continue to move constantly while sleeping" because Scientist 1 argues that one reason we sleep is because moving around at night wastes energy. Thus, we sleep to conserve energy. If sharks expend energy even while sleeping, this would contradict Scientist 1.

When deprived of sleep, chimpanzees would expend more energy at night and require more, not less, food. During spring, when food for bees is abundant, the bees would be able to gain more energy and sleep less, not more.

Example Question #661 : Biology

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. 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 to 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.

Scientist 2’s theory would be most weakened if which of the following were true?

Possible Answers:

Hibernating hedgehogs often become sick soon after waking.

Cows show decreased melatonin at night.

Nocturnal mice have low hormone levels in the morning.

Salmon do not require sleep during the mating season.

Snakes are diurnal because they are cold blooded.

Correct answer:

Hibernating hedgehogs often become sick soon after waking.

Explanation:

Scientist 2 claims that animals get sick more easily (have a weakened immune system) when they are deprived of sleep. Thus, if animals frequently get sick after long periods of sleep, it would contradict Scientist 2's claim. "Hibernating hedgehogs often become sick soon after waking" is the correct answer.

Nocturnal mice would have low hormone levels in the morning, according to Scientist 2's theory, and would then replenish those hormones while they sleep during the day. If cows show decreased melatonin at night, it would contradict the facts listed about melatonin at the beginning of the passage, but would not directly conflict with Scientist 2.

Example Question #662 : Act Science

In the 1980’s, an epidemic of bovine spongiform encephalopathy, or mad cow disease, swept through cattle herds in the United Kingdom.   Scientists and veterinarians were troubled and had a difficult time managing the disease because it spread from one animal to another, and behaved differently than other diseases in the past. 

When infectious material from affected animals was treated with high levels of radiation, for example, the material remained infectious.  All known bacteria or viruses that carry disease would have been killed by such a treatment.  Additionally, some animals developed the disease without first being exposed to sick animals. Perhaps most frustratingly, among those animals that are exposed before becoming sick, it can take many years after exposure for illness to appear.

There quickly emerged two distinct explanations for the disease. 

Scientist 1:

Mad cow disease is unlike any disease we have handled before.  It is increasingly clear that the best explanation for the disease’s dynamics involve proteins, called the protein-only hypothesis.   These protein molecules are likely causative of the disease, and they lack any DNA or RNA.  It is damage to these DNA or RNA molecules that kills bacteria or viruses when exposed to high levels of radiation.  The most important observations that made scientists consider a unique, protein-only model for this disease involved its resistance to radiation.  Remarkably, this would be the first example of an infectious agent copying itself without DNA or RNA to mediate the process.

Moreover, some animals develop the disease spontaneously, without physically being infected by another animal. This suggests that internal disorder among protein molecules is a potential route to developing disease, and may be accelerated by exposure to other sick animals.

In fact, this is consistent with the proposed mechanism. It is likely that proteins fold incorrectly, and then influence proteins around them to take on this errant conformation.  Some proteins may fold incorrectly by chance, which explains spontaneous disease development.  It also explains the long course of disease, as it takes many years for enough proteins to fold incorrectly and result in observable disease.

Scientist 2:

The suggestion that mad cow disease is caused exclusively by protein, in the absence of DNA or RNA, is such a dramatic departure from accepted biological processes that it warrants careful scrutiny. Additionally, other more conventional explanations should be thoroughly investigated before coming to such a conclusion.

Some scientists have shown that very small particles resembling viruses are visible in infectious material under powerful microscopes.  Additionally, these viruses are consistent in size and shape with known, highly radiation-resistant viruses called polyomaviruses.  It takes much higher-than-typical doses of radiation to cause enough DNA damage to inactivate these viruses.

The observation that mad cow disease occurs spontaneously in some animals is also explained by the viral explanation. Many viruses exist in animals and humans for years, undetected and no causing any observable disease. Sickness or stress can make these viruses reactivate, offering the illusion of spontaneous illness.  All of these observations are consistent with the viral hypothesis.

The observation that some known viruses are radiation resistant and able to go undetected for years is provided in the passage to:

Possible Answers:

Support the plausability of the protein-only hypothesis

Show that other diseases exist known to be caused by only protein, without DNA or RNA

Support the plausability of the viral hypothesis

Refute the viral hypothesis

Neither support nor refute either hypothesis, and is provided strictly for background

Correct answer:

Support the plausability of the viral hypothesis

Explanation:

Scientist 2 briefly discusses the existence of other viruses with features consistent with mad cow disease.  Her intention in the passage is to show that the unusual features of mad cow disease are consistent with observations of known viral diseases, and thus this may be a simpler explanation than the more novel protein-only hypothesis.  In this way, the information is used to support the viral hypothesis.

Example Question #663 : Act Science

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

Which scientist would agree with the statement, “the principle of mass action determines the rate of a reaction based on the saturation of reactants”?

Possible Answers:

Neither scientist would support this statement.

Scientist 2, because he or she believes that oxygen determines metabolic rate.

Scientist 2, because he or she believes that glucose determines metabolic rate.

Scientist 1, because he or she believes that glucose determines metabolic rate.

Scientist 1, because he or she believes that oxygen determines metabolic rate.

Correct answer:

Scientist 1, because he or she believes that oxygen determines metabolic rate.

Explanation:

Scientist 1 believes that metabolic rate is determined mainly by oxygen saturation, which mirrors the principle of mass action. Glucose is produced internally, so saturation is not a relevant measure.

Example Question #662 : Biology

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

Would Scientist 1 agree with Scientist 2’s statement that “respiration has a definite plateau”?

Possible Answers:

Scientist 1 would agree with Scientist 2’s statement because Scientist 1 believes metabolic rate has a distinct upper limit. 

Scientist 1 would not agree with Scientist 2’s statement because Scientist 1 believes metabolic rate has no upper limit. 

Scientist 1 would not agree with Scientist 2’s statement because Scientist 1 believes metabolic rate is not related to respiration.  

Scientist 1 would not agree with Scientist 2’s statement because Scientist 1 believes metabolic rate is determined by oxygen. 

Scientist 1 would agree with Scientist 2’s statement because Scientist 1 believes metabolic rate has no upper limit. 

Correct answer:

Scientist 1 would not agree with Scientist 2’s statement because Scientist 1 believes metabolic rate has no upper limit. 

Explanation:

Scientist 1 states that “metabolic rate will continue to increase as long as the oxygen saturation increases.” This directly contradicts Scientist 2’s statement.

Example Question #664 : Act Science

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

Which of the following statements would Scientist 2 likely endorse?

Possible Answers:

Metabolic rate depends on activity level and the availability of oxygen.

Oxygen is mostly inaccessible in its dissolved form.

None of the other answers is correct.

The metabolic rate of fish is primarily determined by temperature.

Most biological processes have a set range in terms of productivity and efficiency.

Correct answer:

Most biological processes have a set range in terms of productivity and efficiency.

Explanation:

Scientist 2 stresses the balance of reactants in biological processes. He or she also states that biological processes are not indefinite, and that they can only function within specific conditions.

Example Question #664 : Biology

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

Which of the following pieces of new information could support Scientist 2’s view?

Possible Answers:

A study comparing the effects of glucose and oxygen on metabolic rate.

Analysis of the mitochondria of different fish raised in a low-oxygen environment.

A paper showing that angelfish use a different form of biological energy than other animals.

Data showing metabolic rate in relation to day length.

A study analyzing different species within the angelfish family and their responses to varying oxygen saturation.

Correct answer:

A study comparing the effects of glucose and oxygen on metabolic rate.

Explanation:

Scientist 2 relies on the statement that glucose is the primary determinant in metabolic rate. A study where glucose was more effective than oxygen in varying metabolic rate would definitely support Scientist 2.

Example Question #661 : Biology

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

What can be inferred about Scientist 1’s perspective on energy allocation?

Possible Answers:

Most energy produced by respiration is lost to the environment.

 Biological processes require energy, and energy can be transferred between functions.

Angelfish, as cold-blooded animals, do not produce energy.

Energy produced is directly proportional to waste.

Breathing requires more energy than other biological functions.

Correct answer:

 Biological processes require energy, and energy can be transferred between functions.

Explanation:

Scientist 1 implies that energy that is not used for collecting oxygen could be used for metabolic functions. Thus, we can infer that he or she believes that energy can be transferred between major processes.

Example Question #665 : Act Science

Background

During aerobic respiration, oxygen is used to reduce sugars into biologically available energy molecules. An animal’s metabolism is the rate at which the animal can convert nutrients into energy and waste. Scientist 1 and Scientist 2 have different hypotheses concerning the effect of oxygen saturation on the metabolic rate of a certain fish.

Scientist 1

Angelfish are large tropical fish commonly seen in the aquarium trade. As oxygen saturation increases, the angelfish’s metabolic rate will increase, as more oxygen is available for respiration. The fish will be able to process a greater amount of nutrients and produce a greater amount of waste. As the oxygen saturation increases, the fish will be able to breathe more easily, using less energy for oxygen collection. This will further increase the metabolic rate, as the fish spends less energy securing usable oxygen. The metabolic rate will continue to increase as long as the oxygen saturation increases.

Scientist 2

Adequate oxygen saturation is a vital element in aquarium management. Angelfish need an adequate supply of oxygen to achieve a healthy metabolic rate. However, like all biological processes, respiration has a definite plateau. The limiting reagent of aerobic respiration is not oxygen, but glucose. When the supply of glucose is exhausted, respiration stops, regardless of available oxygen. The metabolic rate may increase slightly as oxygen saturation increases, but it will not exceed the maximum determined by available glucose. 

Imagine that a study found that angelfish normally inhabit oxygen-poor habitats. How would this discovery affect each scientist's viewpoint?

Possible Answers:

The new study would support Scientist 1’s view, because angelfish would not be able to absorb oxygen in an environment full of solid particulates.

The new study would discredit Scientist 2’s view, because angelfish would not be able to maintain healthy metabolic rates in oxygen-deprived water.

The new study would support Scientist 2’s view, because angelfish would be able to maintain healthy metabolic rates in oxygen-deprived water.

The new study would discredit Scientist 1’s view, because angelfish would be able to maintain healthy metabolic rates in oxygen-deprived water.

The new study would support Scientist 1’s view, because angelfish would be able to absorb other nutrients in poor water conditions.

Correct answer:

The new study would discredit Scientist 1’s view, because angelfish would be able to maintain healthy metabolic rates in oxygen-deprived water.

Explanation:

Scientist 1 states that angelfish need high oxygen saturation to maintain high metabolic rates. Neither scientist discusses other nutrients or particulates. So, if angelfish are able to thrive at low oxygen, respiration and oxygen would not be positively correlated.

Learning Tools by Varsity Tutors