Life Science (Grades 9–12)
Subtest 2 Sample Items
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Question 1
1. One characteristic that distinguishes living from nonliving things is that living things incorporate substances from their environment to grow. Which of the following examples best illustrates why this characteristic is insufficient to distinguish between the two?
- An iron shovel left out in the rain becomes rusty.
- Two solutions are mixed in a test tube and a precipitate forms.
- Stalactites form on the roof of a limestone cave.
- A beaker of water turns to ice as it is cooled.
Answer to question 1
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0011) Stalactites grow as water evaporates from them, leaving calcite deposits behind that add to the size of the stalactites. However, stalactites do not exhibit many of the other characteristics of living things. For example, stalactites are not composed of cells, do not exhibit the ability to synthesize needed materials, and do not respire. Therefore, growth alone is not adequate to distinguish between living and nonliving things.
Correct Response: C. (Objective 0011) Stalactites grow as water evaporates from them, leaving calcite deposits behind that add to the size of the stalactites. However, stalactites do not exhibit many of the other characteristics of living things. For example, stalactites are not composed of cells, do not exhibit the ability to synthesize needed materials, and do not respire. Therefore, growth alone is not adequate to distinguish between living and nonliving things.
Question 2
2. The illustration shows a sea anemone on the ocean floor.
Which of the following is most likely to be found on the structures labeled X in the illustration of a sea anemone?
- microscopic gills that obtain oxygen from seawater
- nematocysts that can launch a harpoon-like structure filled with toxin for capturing prey
- specialized cells that produce gametes and release them into the surrounding seawater
- pores that release pheromones that repel predators into the environment
Answer to question 2
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0011) Sea anemones are predatory animals related to corals and jellyfish. Specialized cells on the tentacles contain nematocysts, which are filled with toxin. The nematocyst has an external hair that acts as a trigger when touched, causing a harpoon-like structure to explode outward and inject toxin into the skin of a small fish or shrimp, which is then eaten by the sea anemone.
Correct Response: B. (Objective 0011) Sea anemones are predatory animals related to corals and jellyfish. Specialized cells on the tentacles contain nematocysts, which are filled with toxin. The nematocyst has an external hair that acts as a trigger when touched, causing a harpoon-like structure to explode outward and inject toxin into the skin of a small fish or shrimp, which is then eaten by the sea anemone.
Question 3
3. The illustration shows a flamingo's bill with the lamellae visible as hairlike projections.
Flamingoes feed with their heads upside down and their bills partly open. They sweep their heads back and forth in shallow water, trapping small crustaceans and other food particles in the comblike lamellae that are attached to the upper and lower mandibles. This feeding method of the flamingo most resembles that of which of the following animals?
- snails
- giant anteaters
- butterflies
- blue whales
Answer to question 3
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0011) Flamingoes engage in filter feeding by straining water through the lamellae in their bills and using their tongues to clean off the small crustaceans left behind. This is very similar to the method of feeding used by baleen whales, such as the blue whale. These whales feed by straining water through the large plates of baleen hanging at the backs of their mouths, wiping the plates with their tongues, and swallowing the small fish and crustaceans left behind.
Correct Response: D. (Objective 0011) Flamingoes engage in filter feeding by straining water through the lamellae in their bills and using their tongues to clean off the small crustaceans left behind. This is very similar to the method of feeding used by baleen whales, such as the blue whale. These whales feed by straining water through the large plates of baleen hanging at the backs of their mouths, wiping the plates with their tongues, and swallowing the small fish and crustaceans left behind.
Information For Questions 4 and 5
Use the information below and the graphic showing several species of cacti growing in the North American Southwest to answer the questions that follow.
Cacti are flowering plants that are adapted to the harsh conditions found in the arid and semiarid areas of the world. Cacti come in all shapes and sizes. Most cacti have succulent stems in which they store water and food. To protect those resources from vertebrate herbivores, most cacti have sharp spines formed from modified leaves.
Question 4
4. Cacti differ from most other flowering plants in which of the following ways?
- Food and water can be stored in the stem for later use.
- Flowering occurs irregularly during any season of the year.
- Photosynthesis takes place in the stem rather than in leaves.
- Flowers may be pollinated by vertebrates as well as by insects.
Answer to question 4
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0011) Cacti live in an environment in which water is a critical limiting factor. One adaptation to this environment is to limit the amount of water that is lost to transpiration by eliminating leaves, which have a high surface area to volume ratio. Although leaves are the primary site of photosynthesis in most plants, cacti have transferred the site of photosynthesis from leaves to their green, fleshy stems.
Correct Response: C. (Objective 0011) Cacti live in an environment in which water is a critical limiting factor. One adaptation to this environment is to limit the amount of water that is lost to transpiration by eliminating leaves, which have a high surface area to volume ratio. Although leaves are the primary site of photosynthesis in most plants, cacti have transferred the site of photosynthesis from leaves to their green, fleshy stems.
Question 5
5. The shallow, extensive root systems of most cacti are adapted primarily to which of the following characteristics of the desert environment?
- Desert soils are loose and friable and strong winds often blow across the surface of the land.
- Temperatures in the desert vary greatly from day to night and from one season to another.
- Rainfall in the desert occurs primarily as heavy cloudbursts during infrequent, short-lived storms.
- High evaporation rates often lead to high concentrations of salts in desert soils.
Answer to question 5
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0014) Cacti live in an environment in which precipitation is rare. Rain, when it does occur, is usually heavy and of short duration. Moreover, water sinks quickly into the sandy soil and is lost to the roots of desert plants. The extensive, shallow root system of most cacti enables the plant to rapidly absorb as much moisture as possible over a wide area before it sinks into the ground.
Correct Response: C. (Objective 0014) Cacti live in an environment in which precipitation is rare. Rain, when it does occur, is usually heavy and of short duration. Moreover, water sinks quickly into the sandy soil and is lost to the roots of desert plants. The extensive, shallow root system of most cacti enables the plant to rapidly absorb as much moisture as possible over a wide area before it sinks into the ground.
Question 6
6. Pine leaves and maple leaves shown in the illustration differ greatly in shape.
image on the left is of maple tree leaves that are broad and have a large surface area, the image on the right is of pine needles that are skinny and long with little surface area.
The primary adaptive advantage of the pine needle over the broad, flat shape of most deciduous tree leaves is that pine needles are better able to:
- resist attacks by insect and vertebrate predators in habitats where predator pressure is intense.
- inimize the nightly loss of heat generated by the plant during the day in habitats where daily temperature fluctuations are great.
- discourage competing plants from growing under the tree in habitats where competition for sunlight is intense.
- minimize water loss from transpiration in habitats where water availability is limited.
Answer to question 6
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0012) Pine trees and other gymnosperms are dominant in the boreal forest environment. With cold temperatures, primary productivity in the boreal forest is low and trees cannot afford to shed their leaves each year. At the same time, water is locked up as ice through much of the year and water loss through transpiration is a major problem. Pine needles have a much lower surface area to volume ratio than the broad, thin leaves of deciduous trees and lose less water to transpiration as a result.
Correct Response: D. (Objective 0012) Pine trees and other gymnosperms are dominant in the boreal forest environment. With cold temperatures, primary productivity in the boreal forest is low and trees cannot afford to shed their leaves each year. At the same time, water is locked up as ice through much of the year and water loss through transpiration is a major problem. Pine needles have a much lower surface area to volume ratio than the broad, thin leaves of deciduous trees and lose less water to transpiration as a result.
Question 7
7. The coelom shown in the cross section of the earthworm makes up much of the internal volume of the animal.
Which of the following is the primary function of the coelom in the earthworm?
- circulating blood throughout the body
- storing and excreting wastes
- providing hydrostatic support
- digesting food and absorbing nutrients
Answer to question 7
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0012) The coelom is a fluid-filled cavity formed within the mesoderm of animals. In animals that lack an external or internal skeleton, the coelom forms a hydrostatic supporting and shock-absorbing system that allows the animal to maintain its shape in the presence of outside forces.
Correct Response: C. (Objective 0012) The coelom is a fluid-filled cavity formed within the mesoderm of animals. In animals that lack an external or internal skeleton, the coelom forms a hydrostatic supporting and shock-absorbing system that allows the animal to maintain its shape in the presence of outside forces.
Question 8
8. Which of the following plant structures is specially adapted to prevent water loss?
- leaf cuticle
- cork cambium
- root hairs
- primary xylem
Answer to question 8
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0012) A waxy cuticle coats the leaves of plants. This cuticle is composed of lipid materials, which are hydrophobic and therefore prevent the easy passage of water through them.
Correct Response: A. (Objective 0012) A waxy cuticle coats the leaves of plants. This cuticle is composed of lipid materials, which are hydrophobic and therefore prevent the easy passage of water through them.
Question 9
9. The firefly gets its name from its light organ. In a reaction involving oxygen and a bioluminescent enzyme, flashes of light are emitted from the firefly's body in a pattern unique to its species. Which of the following functions is most likely the purpose of the light organ?
- producing heat
- attracting a mate
- helping to locate a food source
- communicating the presence of a predator
Answer to question 9
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0012) In nature, bioluminescence can be used in many ways. However, in the firefly, the flashing patterns of light are unique to the species. This means that the flashes can help a firefly identify others of its species and, thus, locate a suitable mate. This prezygotic reproductive barrier most likely evolved in order to prevent mating between different species.
Correct Response: B. (Objective 0012) In nature, bioluminescence can be used in many ways. However, in the firefly, the flashing patterns of light are unique to the species. This means that the flashes can help a firefly identify others of its species and, thus, locate a suitable mate. This prezygotic reproductive barrier most likely evolved in order to prevent mating between different species.
Question 10
10. The table below shows four steps in the inflammatory response.
W |
X |
Y |
Z |
Phagocytic cells consume pathogens and cell debris. |
Tissue cells release histamine and prostaglandin. |
Fluid and clotting elements move to the site and clotting begins. |
Capillaries dilate and become more permeable. |
Which of the following sequences lists the steps of the inflammatory response in the correct order?
- X Tissue cells release histamine and prostaglandin, Z Capillaries dilate and become more permeable, Y Fluid and clotting elements move to the site and clotting begins, W Phagocytic cells consume pathogens and cell debris
- Z Capillaries dilate and become more permeable, X Tissue cells release histamine and prostaglandin, Y Fluid and clotting elements move to the site and clotting begins., W Phagocytic cells consume pathogens and cell debris
- X Tissue cells release histamine and prostaglandin, W Phagocytic cells consume pathogens and cell debris, Y Fluid and clotting elements move to the site and clotting begins., Z Capillaries dilate and become more permeable
- Z Capillaries dilate and become more permeable, W Phagocytic cells consume pathogens and cell debris, X Tissue cells release histamine and prostaglandin, Y Fluid and clotting elements move to the site and clotting begins.
Answer to question 10
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0013) The inflammatory immune response is part of the second line of defense of the human immune system. Inflammation is a nonspecific response; it will occur when any foreign pathogen, such as a bacterium or virus, has invaded the body. In response to a foreign pathogen, injured cells release chemical messengers that stimulate capillaries near the injury to dilate. This permits clotting proteins and fluids to leave the blood and begin the clotting process. Other chemical signals attract phagocytic white blood cells to the site to consume the foreign invaders and clean up debris.
Correct Response: A. (Objective 0013) The inflammatory immune response is part of the second line of defense of the human immune system. Inflammation is a nonspecific response; it will occur when any foreign pathogen, such as a bacterium or virus, has invaded the body. In response to a foreign pathogen, injured cells release chemical messengers that stimulate capillaries near the injury to dilate. This permits clotting proteins and fluids to leave the blood and begin the clotting process. Other chemical signals attract phagocytic white blood cells to the site to consume the foreign invaders and clean up debris.
Question 11
11. Use the information below to answer the question that follows.
Lyme disease is a serious illness that is caused by spirochete bacteria in the genus Borrelia. The disease is transmitted by the bite of a deer tick that has acquired the parasite from feeding on an alternate host, usually a small rodent. Infections respond well to antibiotic treatment if the treatment is started soon after infection. Untreated infections that have been disseminated to major organ systems are much more difficult to treat and can lead to persistent and severe symptoms and occasional fatalities.
Which of the following best explains why it is unlikely that Borrelia will develop immunity to the antibiotics that are commonly used to treat Lyme disease?
- Borrelia bacteria, like most spirochetes, are extremely delicate organisms that are easily killed by antibiotics.
- Borrelia bacteria typically reside in non-human animals and are not usually exposed to antibiotics.
- Antibiotic-resistant Borrelia individuals are less fit than normal individuals when antibiotics are not present.
- Populations of Borrelia bacteria, like most spirochetes, generally lack the genetic variability to evolve antibiotic resistance.
Answer to question 11
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0013) Bacteria develop antibiotic resistance when their populations are frequently exposed to the selective pressures of antibiotics in the environment. With repeated exposures, susceptible individuals are killed and resistant individuals form the basis of the next generation. In the case of Borrelia, most populations live in non-human animals and do not experience antibiotics in their environments. Moreover, those individuals that do encounter antibiotics in humans are only very rarely transmitted to other humans and die out without transmitting their genes into the larger population.
Correct Response: B. (Objective 0013) Bacteria develop antibiotic resistance when their populations are frequently exposed to the selective pressures of antibiotics in the environment. With repeated exposures, susceptible individuals are killed and resistant individuals form the basis of the next generation. In the case of Borrelia, most populations live in non-human animals and do not experience antibiotics in their environments. Moreover, those individuals that do encounter antibiotics in humans are only very rarely transmitted to other humans and die out without transmitting their genes into the larger population.
Question 12
12. The extensive rough endoplasmic reticulum in activated B cells is associated with these cells' ability to:
- produce large quantities of antibodies.
- lyse cells infected by virus particles.
- produce cytokines that induce fever.
- engulf and digest virus particles.
Answer to question 12
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0013) When an inactive B cell encounters an appropriate antigen it interacts with a helper T cell to become activated. The activated B cell divides and produces numerous daughter cells that contain a large amount of rough endoplasmic reticulum. This rough endoplasmic reticulum is studded with many ribosomes that are the sites for protein synthesis. The ribosomes in the activated B cells churn out antibodies that are specific for the antigen that initiated the process.
Correct Response: A. (Objective 0013) When an inactive B cell encounters an appropriate antigen it interacts with a helper T cell to become activated. The activated B cell divides and produces numerous daughter cells that contain a large amount of rough endoplasmic reticulum. This rough endoplasmic reticulum is studded with many ribosomes that are the sites for protein synthesis. The ribosomes in the activated B cells churn out antibodies that are specific for the antigen that initiated the process.
Question 13
13. Which of the following descriptions provides the best example of secondary immunity?
- An infant is born with antibodies originally produced by the mother during late pregnancy.
- An adult who had measles as a child will quickly produce antibodies to the disease when the pathogen is detected again.
- Farmers who contracted cowpox exhibit resistance to the closely related smallpox virus.
- Children at a summer camp are injected with antibodies against hepatitis A after one camper is diagnosed with the illness.
Answer to question 13
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0013) In the primary immune response, B cells are produced against a specific pathogen. At the same time, some memory B cells are produced to provide future immunity. These memory cells persist in the body and will respond quickly when someone is exposed to the same pathogen again. This response is known as the secondary immune response.
Correct Response: B. (Objective 0013) In the primary immune response, B cells are produced against a specific pathogen. At the same time, some memory B cells are produced to provide future immunity. These memory cells persist in the body and will respond quickly when someone is exposed to the same pathogen again. This response is known as the secondary immune response.
Question 14
14. Periodical cicada of the genus Magicicada have an extremely long life cycle. These insects spend 13–17 years underground as nymphs. All the cicadas in an area emerge within a few days of each other and immediately molt and become adults. This behavior most likely represents an adaptation for:
- ensuring that each member of the population is able to find a partner and mate.
- taking advantage of regularly occurring and locally abundant food supplies.
- delaying maturation to allow slow growth in a nutrient-poor environment.
- increasing the chances of survival from predation.
Answer to question 14
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0014) This genus of cicada exhibits a long life cycle compared to most insects. This cicada's life cycle of 13–17 years is longer than the life cycles of many insect predators, which reduces the likelihood that predators will adapt to consuming cicadas as their prey. Therefore, it is hypothesized that the long life cycle of cicadas is an adaptation for survival from predation.
Correct Response: D. (Objective 0014) This genus of cicada exhibits a long life cycle compared to most insects. This cicada's life cycle of 13–17 years is longer than the life cycles of many insect predators, which reduces the likelihood that predators will adapt to consuming cicadas as their prey. Therefore, it is hypothesized that the long life cycle of cicadas is an adaptation for survival from predation.
Question 15
15. As shown in the illustration, the loop of Henle in the nephron of animal X is considerably longer than that of animal Y.
Based on this difference, it is likely more important for animal X to be able to:
- maintain hypertonic body fluids in a freshwater environment.
- conserve water in dry climates by producing highly concentrated urine.
- add pheromones used in marking territory or attracting mates.
- move and excrete alkaloids from a diet high in toxic plants.
Answer to question 15
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0014) The loop of Henle is part of the mammalian kidney. This structure uses a countercurrent mechanism to remove water from the filtrate of the kidneys to produce concentrated urine. In desert-adapted mammals such as the kangaroo rat, the loop of Henle is very long to remove as much water as possible from the urine. This water conservation mechanism is so effective in these animals that they can survive without drinking, obtaining water only from the food that they eat.
Correct Response: B. (Objective 0014) The loop of Henle is part of the mammalian kidney. This structure uses a countercurrent mechanism to remove water from the filtrate of the kidneys to produce concentrated urine. In desert-adapted mammals such as the kangaroo rat, the loop of Henle is very long to remove as much water as possible from the urine. This water conservation mechanism is so effective in these animals that they can survive without drinking, obtaining water only from the food that they eat.
Question 16
16. Elephant seals dive to great depths where they hunt rays, squid, large fish, and other prey. Elephant seals have a much larger volume of blood in their bodies than most other animals. Some of the additional volume of blood is stored in special sinuses in their abdomens. They also have a higher concentration of myoglobin in their muscle tissue than most other animals. These characteristics are most likely adaptations associated with the:
- need to store large quantities of oxygen during long dives.
- extreme cold encountered in deep dives.
- need to expend large quantities of energy in catching fast-moving prey.
- high pressure encountered in deep dives.
Answer to question 16
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0014) One of the main functions of the circulatory system is the storage and transport of oxygen in the hemoglobin of red blood cells. Some of this oxygen can also be stored in the myoglobin of muscles for use during activity. The increased volume of blood in the elephant seal provides a greater number of red blood cells and increased hemoglobin to store and transport oxygen while the animal is holding its breath during deep dives. The increased myoglobin also allows more oxygen to be stored in muscle tissue for use during these dives.
Correct Response: A. (Objective 0014) One of the main functions of the circulatory system is the storage and transport of oxygen in the hemoglobin of red blood cells. Some of this oxygen can also be stored in the myoglobin of muscles for use during activity. The increased volume of blood in the elephant seal provides a greater number of red blood cells and increased hemoglobin to store and transport oxygen while the animal is holding its breath during deep dives. The increased myoglobin also allows more oxygen to be stored in muscle tissue for use during these dives.
Question 17
17. Two species of flycatchers are very similar in size and coloration but differ strongly in their vocalizations. The ranges of the two species overlap and they are frequently found together, although one usually feeds in the brushy understory, while the other feeds higher up in mature trees. Males of each species do not respond to the vocalizations of the other species and their nesting territories often overlap. Females choose mates based on vocalizations and possession of a territory, and will not usually mate with males whose vocalizations are characteristic of the other species. Which of the following conclusions is supported by this information?
- Members of each species will eat a wider range of food and occupy more diverse habitats in areas where the species overlap than in areas where they do not.
- Hybrids between the two species are likely to be less fit than members of either species who are not hybrids.
- Members of each species compete strongly with members of the other species for the same resources.
- The two species have recently diverged and will probably reform into a single species in a relatively short time.
Answer to question 17
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0015) When the ranges of two closely related species overlap they may at first interbreed and hybrids will be produced. If the hybrids are as fit as non-hybrids, the two species will likely merge eventually and become one. However, if hybrids are less fit than non-hybrids, there will be rapid selection to ensure that hybridization does not occur. In birds, females have a higher parental investment than males and are penalized to a greater degree for choosing the wrong mate. Therefore, when hybrids are less fit than non-hybrids, there will be rapid selection favoring those females who can recognize an appropriate mate of their own species and who refuse to mate with a member of the other species.
Correct Response: B. (Objective 0015) When the ranges of two closely related species overlap they may at first interbreed and hybrids will be produced. If the hybrids are as fit as non-hybrids, the two species will likely merge eventually and become one. However, if hybrids are less fit than non-hybrids, there will be rapid selection to ensure that hybridization does not occur. In birds, females have a higher parental investment than males and are penalized to a greater degree for choosing the wrong mate. Therefore, when hybrids are less fit than non-hybrids, there will be rapid selection favoring those females who can recognize an appropriate mate of their own species and who refuse to mate with a member of the other species.
Question 18
18. A population of woodland rodent is isolated from the rest of the species by land clearing. Over time, genetic differences between the two populations accumulate, increasing the possibility that the isolated population will become a separate species. Speciation is more likely to occur if the isolated population is:
- large, because recombination is more effective at producing new variants and changing the gene pool in a large population than a small one.
- small, because mutations that change the gene pool by introducing novel genes are more likely to occur in a small population than a large one.
- large, because natural selection will be more likely to change the gene pool of a large population than a small one.
- small, because founder effect and genetic drift will be more likely to change the gene pool in a small population than in a large one.
Answer to question 18
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0015) When two populations become separated by a geographic barrier, their gene pools begin to diverge. When the barrier breaks down and the populations are once again sympatric, speciation may occur if hybrids are less fit than non-hybrids in each population. Reduction in fitness of hybrids depends, in part, on the amount of genetic differences that have accumulated between the gene pools of the two populations. In a small population, random factors such as founder effect and genetic drift can cause rapid genetic change as alleles are lost or fixed. Speciation is more likely, therefore, if one of the isolated populations is very small than if both populations are large.
Correct Response: D. (Objective 0015) When two populations become separated by a geographic barrier, their gene pools begin to diverge. When the barrier breaks down and the populations are once again sympatric, speciation may occur if hybrids are less fit than non-hybrids in each population. Reduction in fitness of hybrids depends, in part, on the amount of genetic differences that have accumulated between the gene pools of the two populations. In a small population, random factors such as founder effect and genetic drift can cause rapid genetic change as alleles are lost or fixed. Speciation is more likely, therefore, if one of the isolated populations is very small than if both populations are large.
Question 19
19. Which of the following is the best example of how sexual selection can change the frequency of genotypes in a bird species?
- Females that choose long-tailed males as mates produce long-tailed sons that are more likely to find mates in the next generation.
- Males that sing from a conspicuous perch are more likely to be eaten by predators than females that remain hidden in the foliage.
- Females that forage at a different height than males produce larger clutch sizes than those who compete directly with males for food.
- Males that use songs and displays rather than actual fighting to establish territories are less likely to be injured and die.
Answer to question 19
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0015) Sexual selection refers to selection for traits that confer an advantage to individuals, usually males, in the intraspecific competition for mates. Sexual selection can involve traits that confer an advantage to males in combat with other males (e.g., horns, antlers). In birds, sexual selection often involves traits that enhance a male's chances of being chosen as a mate by a female. Examples of such traits might be long feathers, bright colors, or complex displays. Many of these traits serve to signal the male's physical strength and condition to prospective mates. However, even traits that may seem maladaptive, such as excessively long tail feathers, may be selected because females that break ranks and choose males with less developed traits penalize their male offspring's chances of mating in the next generation.
Correct Response: A. (Objective 0015) Sexual selection refers to selection for traits that confer an advantage to individuals, usually males, in the intraspecific competition for mates. Sexual selection can involve traits that confer an advantage to males in combat with other males (e.g., horns, antlers). In birds, sexual selection often involves traits that enhance a male's chances of being chosen as a mate by a female. Examples of such traits might be long feathers, bright colors, or complex displays. Many of these traits serve to signal the male's physical strength and condition to prospective mates. However, even traits that may seem maladaptive, such as excessively long tail feathers, may be selected because females that break ranks and choose males with less developed traits penalize their male offspring's chances of mating in the next generation.
Question 20
20. A mutation arises in a species of bedbug that enables an individual bedbug to resist a common pesticide. Over time, the percentage of the population of bedbugs that expresses the resistant gene increases greatly. This situation is an example of which type of natural selection?
- stabilizing
- convergent
- disruptive
- directional
Answer to question 20
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0015) In directional selection, a particular allele has a competitive advantage over others. Its competitive advantage allows for greater reproductive success of that individual. Therefore, the allele will be selected for, changing the frequency of that allele in the population over time.
Correct Response: D. (Objective 0015) In directional selection, a particular allele has a competitive advantage over others. Its competitive advantage allows for greater reproductive success of that individual. Therefore, the allele will be selected for, changing the frequency of that allele in the population over time.
Question 21
21. In determining evolutionary relationships between fossil species, scientists usually analyze similarities and differences in derived traits, rather than primitive or convergent traits. Which of the following is an example of a derived trait that serves to distinguish birds from their dinosaur ancestors?
- hollow bones
- feathers
- amniote eggs
- endothermy
Answer to question 21
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0016) Scientists now believe that the evidence is overwhelming that birds are descended from dinosaurs. Several lineages of these dinosaurs have feathers, but were not capable of sustained flight. One characteristic of birds that lightens the body and permits efficient flight is the presence of hollow bones reinforced by bony struts. Hollow bones are present in birds but not in their dinosaur ancestors, and thus represent a derived trait that distinguishes between the two groups.
Correct Response: A. (Objective 0016) Scientists now believe that the evidence is overwhelming that birds are descended from dinosaurs. Several lineages of these dinosaurs have feathers, but were not capable of sustained flight. One characteristic of birds that lightens the body and permits efficient flight is the presence of hollow bones reinforced by bony struts. Hollow bones are present in birds but not in their dinosaur ancestors, and thus represent a derived trait that distinguishes between the two groups.
Question 22
22. Coelacanths and lungfish are surviving members of a group of fishes called lobe-finned fishes. Lobe-finned fishes were common and diverse during the Devonian period but only a few species remain. The evolutionary significance of the Devonian lobe-finned fishes is primarily due to the fact that they were:
- the first fishes with cartilaginous skeletons and were ancestral to living sharks and rays.
- ancestral to all living ray-finned fishes, including modern teleost species.
- the primary link between the early jawless fishes and the later jawed fishes.
- ancestral to all tetrapods, including amphibians, reptiles, birds, and mammals.
Answer to question 22
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0016) The pectoral and pelvic girdle and fins of lobe-finned fishes exhibit bones that are homologous to those of the tetrapod limb. The fins of one clade of lobe-finned fishes, the tetrapodomorphs, strongly resemble the limbs of the earliest transitional forms between fishes and amphibians. The lobe-finned fishes also included groups that had functional lungs, such as the lungfish and the tetrapodomorphs. These lungs allowed descendants of these fish to survive out of water in the terrestrial environment.
Correct Response: D. (Objective 0016) The pectoral and pelvic girdle and fins of lobe-finned fishes exhibit bones that are homologous to those of the tetrapod limb. The fins of one clade of lobe-finned fishes, the tetrapodomorphs, strongly resemble the limbs of the earliest transitional forms between fishes and amphibians. The lobe-finned fishes also included groups that had functional lungs, such as the lungfish and the tetrapodomorphs. These lungs allowed descendants of these fish to survive out of water in the terrestrial environment.
Question 23
23. The horseshoe crab and the opossum are both examples of organisms whose current morphological structure appears very similar to that of their ancestors' fossilized remains. This morphological stability is most frequently associated with organisms that:
- reproduce sexually and provide little parental care for young.
- possess specialized adaptations for a particular food source.
- inhabit stable environments and are dietary generalists.
- occupy a low trophic level within their respective ecosystems.
Answer to question 23
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0016) Horseshoe crabs and opossums are examples of organisms that have a physical appearance that appears to have changed relatively little over millions of years. This apparently slow morphological evolution is due to stabilizing selection. Stabilizing selection occurs when environmental conditions favor individuals with average, rather than extreme, phenotypes. A given phenotype can be maintained over millions of years because an organism has inhabited environments or niches that have changed slowly over time. Other factors can result in a stable morphology, such as an ability to eat a wide variety of food sources or to survive in wider variations of habitat conditions (e.g., tolerance of changes in temperature, salinity, dissolved oxygen). This is because a greater tolerance to changes in conditions or food sources increases a species' adaptability to environmental change.
Correct Response: C. (Objective 0016) Horseshoe crabs and opossums are examples of organisms that have a physical appearance that appears to have changed relatively little over millions of years. This apparently slow morphological evolution is due to stabilizing selection. Stabilizing selection occurs when environmental conditions favor individuals with average, rather than extreme, phenotypes. A given phenotype can be maintained over millions of years because an organism has inhabited environments or niches that have changed slowly over time. Other factors can result in a stable morphology, such as an ability to eat a wide variety of food sources or to survive in wider variations of habitat conditions (e.g., tolerance of changes in temperature, salinity, dissolved oxygen). This is because a greater tolerance to changes in conditions or food sources increases a species' adaptability to environmental change.
Question 24
24. Sea stars ("starfish") and corals are both large clades of marine invertebrates. However, on the tree of life, sea stars are placed significantly closer to the freshwater vertebrate goldfish clade than they are to corals. Which of the following statements best explains why sea stars are placed closer to goldfish than to coral on the tree of life?
- The geographical origin of sea stars is closer to that of goldfish than to that of corals.
- Sea stars share a more recent common ancestor with goldfish than they do with corals.
- The phenotype of sea stars is more similar to that of goldfish than it is to that of corals.
- Sea stars originated closer in time to the origin of goldfish than to the origin of corals.
Answer to question 24
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0016) An evolutionary tree depicts organisms according to their phylogenetic relationships to other organisms or groups of organisms. On phylogenetic trees, organisms at the roots are ancestral. Branches on the tree arise when clades diverge evolutionarily. As a result, the more closely organisms are related, the more recent their common ancestor is and the closer together they will be on the tree.
Correct Response: B. (Objective 0016) An evolutionary tree depicts organisms according to their phylogenetic relationships to other organisms or groups of organisms. On phylogenetic trees, organisms at the roots are ancestral. Branches on the tree arise when clades diverge evolutionarily. As a result, the more closely organisms are related, the more recent their common ancestor is and the closer together they will be on the tree.
Question 25
25. Which of the following relationships is the best example of parasitism?
- The female European cuckoo lays its eggs in the nests of smaller birds so that its young can be raised by the parents at the expense of their own young.
- The black walnut tree secretes a chemical in its roots that inhibits the respiration and growth of several competing tree species.
- Large numbers of bacteria that live in the rumen of ungulates break down cellulose and other hard-to-digest components of grass.
- Leafcutter ants cultivate and feed upon a fungus that grows on vegetation that the ants have carried into their nest.
Answer to question 25
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0017) Parasitism is defined as a symbiotic relationship between two species that confers an advantage on one species at the expense of the other. Several birds, including European cuckoos and North American cowbirds, are considered nest parasites because they lay their eggs in other birds' nests. The cuckoo's young hatches first and then pushes the eggs of the host species out of the nest so that the host adults will spend all their time and energy feeding the imposter.
Correct Response: A. (Objective 0017) Parasitism is defined as a symbiotic relationship between two species that confers an advantage on one species at the expense of the other. Several birds, including European cuckoos and North American cowbirds, are considered nest parasites because they lay their eggs in other birds' nests. The cuckoo's young hatches first and then pushes the eggs of the host species out of the nest so that the host adults will spend all their time and energy feeding the imposter.
Question26
26. Use the information below to answer the question that follows.
The North American subspecies of the red knot is a medium-sized shorebird that breeds in the Canadian Arctic. The birds nest on the ground and feed on insects, spiders, and larvae. Predators of adults, eggs, and young include Arctic foxes, hawks, and owls. Knots winter in South America where they feed on various bivalves, gastropods, and small crabs. During the long migration from the wintering grounds to the breeding grounds, the knots time their journey to arrive in Delaware Bay just as millions of horseshoe crabs lay their eggs. The knots rest and gorge on the eggs before continuing their flight north to the Canadian Arctic.
Which of the following would most likely lead to a precipitous decline in the population of the North American subspecies of the red knot?
- human harvesting of bivalves in the knots' wintering grounds
- increases in the populations of foxes, hawks, and owls in the Arctic
- human harvesting of horseshoe crabs in Delaware Bay
- increases in the populations of other shorebirds that breed in the Arctic
Answer to question 26
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0017) Many animal species depend on critical resources at certain times of the year or stages in the life cycle. Critical resources are those that sustain the population in times of vulnerability and that cannot be easily replaced. Red knot populations are most stressed during migration when they must fly continuously for many miles without extensive stops for feeding. By the time they have reached Delaware Bay, the knots have exhausted most of their stored food and must refuel before continuing their journey. The huge numbers of horseshoe crab eggs are thus a critical resource for the red knot population, and any disruption of this food supply threatens the survival of this species in eastern North America.
Correct Response: C. (Objective 0017) Many animal species depend on critical resources at certain times of the year or stages in the life cycle. Critical resources are those that sustain the population in times of vulnerability and that cannot be easily replaced. Red knot populations are most stressed during migration when they must fly continuously for many miles without extensive stops for feeding. By the time they have reached Delaware Bay, the knots have exhausted most of their stored food and must refuel before continuing their journey. The huge numbers of horseshoe crab eggs are thus a critical resource for the red knot population, and any disruption of this food supply threatens the survival of this species in eastern North America.
Question 27
27. The spring and fall turnover of water in most temperate lakes and ponds is due to temperature changes in surface water at the start of those seasons. Water is most dense at 4°C. As surface water warms to this temperature in the spring it sinks and deeper water rises to the surface. The process is repeated as surface water cools to 4°C in the fall. Which of the following best describes how this seasonal turnover affects the ecology of the lake or pond?
- Fish and other aquatic organisms must be adapted to life at both the surface and bottom of the lake or pond.
- Variation in water temperature with depth is minimal so productivity is similar from the surface of the lake or pond to the bottom.
- Productivity is increased because nutrient-rich water from the benthic zone is mixed with oxygen-rich water in the photic zone.
- Organisms that make up food webs in the photic zone rarely interact with those that make up food webs in the benthic zone.
Answer to question 27
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0017) Food webs in lakes and ponds depend on the reproduction and growth of primary producers such as algae and aquatic plants. These need light, oxygen, and nutrients for optimal growth. Light and oxygen are plentiful in the upper, photic zone, but nutrients are lost as organisms die and sink to the bottom. The seasonal turnover in spring and fall brings these nutrients from the bottom back to the water's surface and restores them for use in the photic zone.
Correct Response: C. (Objective 0017) Food webs in lakes and ponds depend on the reproduction and growth of primary producers such as algae and aquatic plants. These need light, oxygen, and nutrients for optimal growth. Light and oxygen are plentiful in the upper, photic zone, but nutrients are lost as organisms die and sink to the bottom. The seasonal turnover in spring and fall brings these nutrients from the bottom back to the water's surface and restores them for use in the photic zone.
Question 28
28. A student lives in a wooded area with many birch trees, some of which have mistletoe plants living on them. Upon observing the trees for several months, the student notices that the trees with the mistletoe plants have lost some outer branches and are showing less growth than the other birches. The mistletoe plants still appear healthy. This observation is good evidence that the relationship between the two plant species is most likely:
- mutualistic.
- competitive.
- parasitic.
- commensal.
Answer to question 28
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0017) In a parasitic relationship, one organism benefits and the other is harmed. In the example given, the mistletoe benefits, thriving upon nutrients from the birch tree. At the same time, the birch tree is harmed, losing some branches and exhibiting poor growth.
Correct Response: C. (Objective 0017) In a parasitic relationship, one organism benefits and the other is harmed. In the example given, the mistletoe benefits, thriving upon nutrients from the birch tree. At the same time, the birch tree is harmed, losing some branches and exhibiting poor growth.
Question 29
29. The graph shows population cycling over 50 years for a predator and its favored prey species.
The primary y axis shows prey individuals per square kilometer and the x axis shows time in years. The secondary y axis shows the number of predator individuals per square kilometer. The general pattern of the graph suggests that the predator population increases in response to increases in the prey population and decreases drastically in response to drastic decreases in the prey population.
Which of the following is the most likely conclusion that can be drawn from the information presented in this graph?
- Both predator and prey species must compete with a wide range of other species.
- The carrying capacity of the environment is stable over time for the prey species.
- Mortality is density independent in both predator and prey species.
- The predator lacks large populations of alternative prey species.
Answer to question 29
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0018) The relationship shown in the diagram is characteristic of predator-prey relationships in relatively simple ecosystems such as the boreal forest. The fact that population increases and decreases of the predator mirror those of the prey indicates that the predator cannot easily switch to other prey animals when the population of the favored prey crashes.
Correct Response: D. (Objective 0018) The relationship shown in the diagram is characteristic of predator-prey relationships in relatively simple ecosystems such as the boreal forest. The fact that population increases and decreases of the predator mirror those of the prey indicates that the predator cannot easily switch to other prey animals when the population of the favored prey crashes.
Question 30
30. Survivorship curves depict the number of individuals that survive at each point in the life span of a particular species.
Graph showing a survivorship curve with number of survivors open parenthesis log scale close parenthesis on the y axis and percentage of maximum life span on the x axis. The line on the graph starts about halfway up the the y axis and decreases very slowly as it approaches fifty on the x axis. Soon after 50 the line starts decreasing at a faster rate and then drops very quickly down to 100 on the x axis.
The idealized survivorship curve shown would most likely describe mortality in which of the following species?
- deer mouse
- blue whale
- robin
- grasshopper
Answer to question 30
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0018) Survivorship curves show the percentage of the population that survives to different ages. This curve shows a species in which there is low mortality until late in adulthood, when mortality rapidly increases. This curve is characteristic of long-lived species, such as the blue whale, that protect and care for their young and that have few natural enemies.
Correct Response: B. (Objective 0018) Survivorship curves show the percentage of the population that survives to different ages. This curve shows a species in which there is low mortality until late in adulthood, when mortality rapidly increases. This curve is characteristic of long-lived species, such as the blue whale, that protect and care for their young and that have few natural enemies.
Question 31
31. Which of the following features are characteristic of the tundra biome?
- low altitude, rich topsoil, hot summers and cold winters
- high precipitation, high species diversity, nutrient-poor soil
- hot days and cool nights, low precipitation, low humidity
- low precipitation, low species diversity, high latitude
Answer to question 31
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0018) Characteristics such as precipitation, temperature, and type of vegetation are used to classify biomes. These factors also determine which organisms will be able to survive in the biome and which adaptations will support survival. Low precipitation and cold temperatures are limiting factors in the tundra biome, which is found in the Arctic, Antarctic, and alpine regions.
Correct Response: D. (Objective 0018) Characteristics such as precipitation, temperature, and type of vegetation are used to classify biomes. These factors also determine which organisms will be able to survive in the biome and which adaptations will support survival. Low precipitation and cold temperatures are limiting factors in the tundra biome, which is found in the Arctic, Antarctic, and alpine regions.
Question 32
32. Per unit area, which of the following zones of the marine biome has the least amount of species diversity?
- photic
- abyssal
- neritic
- intertidal
Answer to question 32
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0018) Like the terrestrial environment, the ocean is categorized into several zones based on a variety of factors, such as exposure to light. The abyssal zone is an extremely deep zone, beginning at around 2,000m depth, and covers much of the ocean basins. This depth presents special challenges for survival. Organisms living in the abyssal zone must be able to live with cold temperatures and relatively high pressure of water on their bodily structures. More important, there is a lack of nutrients available to enable organisms to grow and reproduce. This is because the abyssal zone is too deep to allow light for photosynthesis. There is some primary production occurring at hydrothermal vents, due to the chemical energy present there. However, these vents represent small oases in an otherwise oceanic desert. Thus, most of the energy entering the abyssal plane is debris sinking down from higher zones, and this energy is supplemented by hydrothermal vents. Combined with the physical limitations of the zone, these limits result in lower species diversity than marine zones closer to the surface and closer to shore.
Correct Response: B. (Objective 0018) Like the terrestrial environment, the ocean is categorized into several zones based on a variety of factors, such as exposure to light. The abyssal zone is an extremely deep zone, beginning at around 2,000m depth, and covers much of the ocean basins. This depth presents special challenges for survival. Organisms living in the abyssal zone must be able to live with cold temperatures and relatively high pressure of water on their bodily structures. More important, there is a lack of nutrients available to enable organisms to grow and reproduce. This is because the abyssal zone is too deep to allow light for photosynthesis. There is some primary production occurring at hydrothermal vents, due to the chemical energy present there. However, these vents represent small oases in an otherwise oceanic desert. Thus, most of the energy entering the abyssal plane is debris sinking down from higher zones, and this energy is supplemented by hydrothermal vents. Combined with the physical limitations of the zone, these limits result in lower species diversity than marine zones closer to the surface and closer to shore.
Question 33
33.
A diagram consists of four rectangles stacked on top of each other to form a pyramid. The length of the rectangles decreases from bottom to top. The bottom (first) rectangle is labeled producers. The next (second) rectangle up is labeled primary consumers and decomposers. The third rectangle is labeled secondary consumers. The top rectangle is labeled tertiary consumers. The efficiency of energy transfer between the trophic levels is labeled as follows: 20% between the bottom rectangle and the second rectangle, 15% between the second and third rectangles, and 10% between the third and top rectangles.
The primary producers in the productivity pyramid above generate 1000 g/m²/year of biomass. If the efficiency of energy transfers between trophic levels are as shown, what will be the production of biomass by tertiary consumers?
If the producers at the bottom of the pyramid shown generate one thousand grams of biomass per square meter per year, what will be the production of biomass by the tertiary producers?
- 3 g/m²/year3 grams per square meter per year
- 90 g/m²/year90 grams per square meter per year
- 450 g/m²/year450 grams per square meter per year
- 612 g/m²/year612 grams per square meter per year
Answer to question 33
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0019) The source of energy for producers is the sun. The transfer of energy from producers up a food chain is less than 100% because some energy is used by the producers and some is lost as heat. To determine how much energy is transferred to each level of the food chain shown, take the percent of energy transferred to a trophic level from the amount of energy that the level below it started with. So, in the productivity pyramid pictured, the producers have 1000 g/m2/year. To find the amount of energy that the primary consumers and decomposers have, take 20% of the energy from the producers, or 1000 g/m2/year * 0.2 = 200 g/m2/year. This is the amount of energy that is transferred to primary consumers from the producers. Then, 15% of the energy of the primary consumers and decomposers is transferred to secondary consumers. Therefore, 200 g/m2/year * 0.15 = 30 g/m2/year of energy is transferred to secondary consumers. Finally, 10% of the energy from secondary consumers is transferred to tertiary consumers, so 30 g/m2/year * 0.1 = 3 g/m2/year.
Correct Response: A. (Objective 0019) The source of energy for producers is the sun. The transfer of energy from producers up a food chain is less than 100% because some energy is used by the producers and some is lost as heat. To determine how much energy is transferred to each level of the food chain shown, take the percent of energy transferred to a trophic level from the amount of energy that the level below it started with. So, in the productivity pyramid pictured, the producers have 1000 grams per square meter per year. To find the amount of energy that the primary consumers and decomposers have, take 20% of the energy from the producers, or 1000 grams per square meter per year times 0.2 = 200 grams per square meter per year. This is the amount of energy that is transferred to primary consumers from the producers. Then, 15% of the energy of the primary consumers and decomposers is transferred to secondary consumers. Therefore, 200 grams per square meter per year times 0.15 = 30 grams per square meter per year of energy is transferred to secondary consumers. Finally, 10% of the energy from secondary consumers is transferred to tertiary consumers, so 30 grams per square meter per year times 0.1 = 3 grams per square meter per year.
Question 34
34. Net primary productivity in an ecosystem is best defined as the amount of energy that is:
- produced by all the primary producers in the ecosystem.
- used by primary producers in the ecosystem to maintain life processes such as respiration.
- converted into heat by the primary producers in the ecosystem.
- used by primary producers in the ecosystem to build tissue that may be consumed by consumers and decomposers.
Answer to question 34
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0019) Total primary productivity in an ecosystem is all of the energy that is captured by the primary producers in the ecosystem. However, much of this energy is not available to the next trophic level of consumers because it is used in the metabolism of the producers and is lost as heat. Only that proportion of the total primary productivity that goes toward building tissue, defined as the net primary productivity, is available to be used by the next trophic level and ultimately by decomposers.
Correct Response: D. (Objective 0019) Total primary productivity in an ecosystem is all of the energy that is captured by the primary producers in the ecosystem. However, much of this energy is not available to the next trophic level of consumers because it is used in the metabolism of the producers and is lost as heat. Only that proportion of the total primary productivity that goes toward building tissue, defined as the net primary productivity, is available to be used by the next trophic level and ultimately by decomposers.
Question 35
35. Sequestration of carbon in various carbon "sinks" temporarily removes it from participation in the carbon cycle. Which of the following carbon sinks is likely to remove carbon from the carbon cycle for the longest period of time?
- wood of hardwood tree species that grow in wet tropical forests
- bubbles of carbon dioxide trapped in the ice of mountain glaciers
- skeletons of marine organisms that accumulate on the floor of the ocean
- carbon dioxide gas dissolved in the surface waters of the world's oceans
Answer to question 35
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0019) As carbon cycles through the geosphere, atmosphere, and biosphere, it may spend a varying amount of time in different carbon "sinks." Carbon is held in some sinks, such as the tissues of most plants and animals, for only a short period of time. In other sinks, carbon may be effectively removed from the carbon cycle permanently, at least on any timescale that is relevant to human life. The most permanent carbon sinks are carbonate rocks, many of which are formed from the shells of marine organisms that have sunk to the bottom of the ocean. The carbon in these shells will only be released to the environment if the rocks in which they are embedded are uplifted, exposed to the elements, and chemically eroded to produce carbon dioxide.
Correct Response: C. (Objective 0019) As carbon cycles through the geosphere, atmosphere, and biosphere, it may spend a varying amount of time in different carbon "sinks." Carbon is held in some sinks, such as the tissues of most plants and animals, for only a short period of time. In other sinks, carbon may be effectively removed from the carbon cycle permanently, at least on any timescale that is relevant to human life. The most permanent carbon sinks are carbonate rocks, many of which are formed from the shells of marine organisms that have sunk to the bottom of the ocean. The carbon in these shells will only be released to the environment if the rocks in which they are embedded are uplifted, exposed to the elements, and chemically eroded to produce carbon dioxide.
Question 36
36. Which of the following best explains why primary productivity in the open ocean is extremely low compared with that of shallow water ecosystems along coastlines?
- Nutrients lost as organisms die and sink are not quickly replenished by rivers and deepwater upwelling in the open ocean.
- Surface water temperatures in the open ocean are much colder than those in the surface waters along coastlines.
- Salinity in the surface waters of the open ocean is too high for most planktonic organisms to survive and reproduce.
- Food webs in the open ocean are limited to organisms dwelling in surface waters and do not include benthic forms as in coastal waters.
Answer to question 36
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0019) Primary producers in the ocean, such as phytoplankton, require light, oxygen, and nutrients. In the upper layers of the open ocean, light and oxygen are abundant, but nutrients are lacking. In any aquatic environment, nutrients bound up in the bodies of organisms are continually lost as the organisms die and sink. Along the coast, the nutrients that are removed from the system are continually replenished by rivers and streams. In shallow areas along the continental shelf, such as banks and seamounts, upwelling currents replace lost nutrients with nutrients from the ocean floor. In the open ocean, however, lost nutrients are not replaced by either of these processes and become the main factor limiting productivity in this environment.
Correct Response: A. (Objective 0019) Primary producers in the ocean, such as phytoplankton, require light, oxygen, and nutrients. In the upper layers of the open ocean, light and oxygen are abundant, but nutrients are lacking. In any aquatic environment, nutrients bound up in the bodies of organisms are continually lost as the organisms die and sink. Along the coast, the nutrients that are removed from the system are continually replenished by rivers and streams. In shallow areas along the continental shelf, such as banks and seamounts, upwelling currents replace lost nutrients with nutrients from the ocean floor. In the open ocean, however, lost nutrients are not replaced by either of these processes and become the main factor limiting productivity in this environment.
Question 37
37. A scientist is planning a research study to observe the behavior of a primate species in the wild. Which of the following steps will be most important to take to ensure that the data collected provide an accurate view of this species' natural behavior?
- conducting the observations in a way that the scientist's presence does not disturb the animals
- making regular observations of the animals' behavior over a period of at least a full year
- focusing the study on the behavior of an isolated, small population of the animals
- marking individual animals with colored tags so that they can be identified during observation
Answer to question 37
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AnswerAnswer. Click to expand or collapse.
- Correct Response: A. (Objective 0020) A goal of the study described is to visit a primate species in its usual habitat in order to observe the natural behaviors of the animals. It is important that the researcher avoids engaging with the animals or attracting the animals' attention. By attracting an animals' attention, the researcher would insert a stimulus into the daily life of the species that is not normally present, thereby changing its behavior.
Correct Response: A. (Objective 0020) A goal of the study described is to visit a primate species in its usual habitat in order to observe the natural behaviors of the animals. It is important that the researcher avoids engaging with the animals or attracting the animals' attention. By attracting an animals' attention, the researcher would insert a stimulus into the daily life of the species that is not normally present, thereby changing its behavior.
Question 38
38. In areas where their ranges overlap, males of two related species of birds aggressively respond to each other's territorial displays. This behavior has most likely evolved to ensure that:
- energy expended by the male to establish and maintain a territory is minimized.
- nesting pairs of the two species do not compete directly for resources.
- pair bonds between the male and female of a nesting pair are strengthened.
- females of each species choose mates from within their own species.
Answer to question 38
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AnswerAnswer. Click to expand or collapse.
- Correct Response: B. (Objective 0020) Males of many bird species establish and defend territories from males of the same species to ensure that they and their offspring will have exclusive rights to the resources contained in the territory. When males of two related species aggressively respond to each other's territorial signals, it is an indication that the two species are likely to compete for the same resources. Males are treating males of the other species as if they are members of the same species in order to partition the area into exclusive-rights territories.
Correct Response: B. (Objective 0020) Males of many bird species establish and defend territories from males of the same species to ensure that they and their offspring will have exclusive rights to the resources contained in the territory. When males of two related species aggressively respond to each other's territorial signals, it is an indication that the two species are likely to compete for the same resources. Males are treating males of the other species as if they are members of the same species in order to partition the area into exclusive-rights territories.
Question 39
39. In many bird species that use a polygamous system of mating, such as the sage grouse, males defend small areas on a traditional display ground called a lek. During the breeding season, males may spend days continuously on the lek, sparring with neighbors and engaging in extravagant vocal and visual displays. Females gather around the edge of the lek and mate with displaying males, favoring the higher-ranking males who display near the center of the lek. This type of mating system offers which of the following advantages to a female when choosing a mate?
- A female can ensure that her mate will help care for her offspring to protect his investment in time and energy.
- A female can lower the fitness of her offspring's competitors by preventing other females from mating with the dominant male.
- A female can assess which males possess the most adaptive genes to pass down to her offspring.
- A female can ensure that she will possess a large enough territory to provide food for herself and her offspring.
Answer to question 39
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AnswerAnswer. Click to expand or collapse.
- Correct Response: C. (Objective 0020) Lek behavior is common in polygamous animals in which males compete directly with other males for mates. In most polygamous bird species, males do not help to care for the offspring. In these species, selection will favor those females who choose the strongest, healthiest, and most dominant males to father their offspring. Females need some way to assess these qualities in potential mates. The lek display allows males to demonstrate these favorable traits to watching females and ensures that females will pass these traits down to their offspring, including their male offspring who must compete in similar displays when they are grown.
Correct Response: C. (Objective 0020) Lek behavior is common in polygamous animals in which males compete directly with other males for mates. In most polygamous bird species, males do not help to care for the offspring. In these species, selection will favor those females who choose the strongest, healthiest, and most dominant males to father their offspring. Females need some way to assess these qualities in potential mates. The lek display allows males to demonstrate these favorable traits to watching females and ensures that females will pass these traits down to their offspring, including their male offspring who must compete in similar displays when they are grown.
Question 40
40. Use the passage below to answer the question that follows.
A behavioral experiment is set up to examine the actions of laboratory rats after they run a maze repeatedly. At the end of the maze, the rats always enter a chamber with two food dishes. The first food dish has a lightbulb over it that lights up regularly every other minute. If the lever next to that dish is pushed while the lightbulb is lit, then food is released. There is no lightbulb over the second food dish. Moreover, although the lever next to the second dish can be pushed, food is never released into the dish.
If the rats are placed in the maze twice daily for a week, it is most likely that the rats will:
- begin the week pushing both levers and then cease pushing either lever by midweek.
- push the levers for both dishes at about the same frequency throughout the week.
- avoid pushing the lever with no lightbulb as early as their second trip to the maze.
- repeatedly push the lever of the dish with the light until the bulb lights up.
Answer to question 40
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AnswerAnswer. Click to expand or collapse.
- Correct Response: D. (Objective 0020) Experiments with mammals have indicated that animals can recognize that a particular behavior they perform will result in a reward. This is a form of operant conditioning. In this case, the behavior is to push the lever with the lit bulb and the reward is to receive the food treat. The treat reinforces the rats' behavior of lever-pushing
Correct Response: D. (Objective 0020) Experiments with mammals have indicated that animals can recognize that a particular behavior they perform will result in a reward. This is a form of operant conditioning. In this case, the behavior is to push the lever with the lit bulb and the reward is to receive the food treat. The treat reinforces the rats' behavior of lever-pushing