Knowledge Check: Unit 8 — Chapters 44–47 – Biology

Knowledge Check: Unit 8 — Chapters 44–47

Test yourself on Unit 8: Ecology (Chapters 44–47). Every question below was written from the chapters’ own text — their summaries, key terms, explanations, and tables — and none repeats a question from the section pages. There are no hints: treat it like a test. Questions are grouped by the section they come from, so a miss tells you exactly which section to review.

Chapter 44: Ecology and the Biosphere

44.1 The Scope of Ecology

The Karner blue butterfly (Lycaeides melissa samuelis) is a specialist because its females will only oviposit (lay eggs) on which plant?

A form of long-term relationship that has coevolved between two species, from which each species benefits, is called ________.

What kinds of boundaries, natural or artificial, might define the area a population occupies? Give an example of each.

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A population’s area may have natural or artificial boundaries. Natural boundaries might be rivers, mountains, or deserts, while artificial boundaries may be mowed grass, manmade structures, or roads.

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natural boundaries might be rivers, mountains, or deserts
artificial boundaries may be mowed grass, manmade structures, or roads

44.2 Biogeography

Estivation allows animals to survive the hostile conditions of a hot, dry climate; the corresponding adaptation that enables animals to survive cold conditions is called ________.

Which abiotic factor does the jack pine (Pinus banksiana) require in order for its seed cones to open?

How do marine organisms address the challenge of living in water with a higher solute concentration than their own bodies, and what specific adaptation does the marine iguana (Amblyrhynchus cristatus) use?

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Marine organisms are surrounded by water with a higher solute concentration than the organism and are in danger of losing water to the environment because of osmosis. They have morphological and physiological adaptations to retain water and release solutes into the environment. For example, marine iguanas sneeze out water vapor that is high in salt in order to maintain solute concentrations within an acceptable range while swimming in the ocean and eating marine plants.

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marine organisms are surrounded by water with a higher solute concentration than the organism
they are in danger of losing water to the environment because of osmosis
marine iguanas sneeze out water vapor that is high in salt to maintain solute concentrations within an acceptable range

44.3 Terrestrial Biomes

Which terrestrial biome’s vegetation is characterized by adaptations such as deep roots, reduced foliage, and water-storing stems that conserve water?

The boreal forest is also known as the coniferous forest or, by its other name, the ________.

Why are deciduous trees the dominant plant in temperate forests, and what effect does their winter leaf loss have on the biome’s net primary productivity compared to tropical wet forests?

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Because of the moderate annual rainfall and temperatures, deciduous trees are the dominant plant in temperate forests. Deciduous trees lose their leaves each fall and remain leafless in the winter, so no photosynthesis occurs in the deciduous trees during the dormant winter period. Because of this dormant period, the net primary productivity of temperate forests is less than that of tropical wet forests.

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deciduous trees are the dominant plant in temperate forests because of the moderate annual rainfall and temperatures
deciduous trees lose their leaves each fall and remain leafless in the winter
no photosynthesis occurs in the deciduous trees during the dormant winter period
the net primary productivity of temperate forests is less than that of tropical wet forests

44.4 Aquatic Biomes

A type of free-floating marine seaweed found in the neritic zone is called ________.

What is the name for the phenomenon in which rising ocean temperatures cause coral reefs to lose their symbiotic, food-producing algae and much of their color?

How do the abiotic conditions of a river or stream change between its source and where it flows into a lake or ocean, and how does this affect the way downstream predators find food?

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Near its source, a river or stream’s channel is narrow and its current is fast, so silt does not accumulate and photosynthesis comes mostly from algae growing on rocks. As the stream flows farther from its source, the channel widens, the current slows, and more sedimentation occurs, so the water is warmer and less clear. Because the water is murkier downstream, predator vertebrates such as waterfowl, frogs, and fishes are more likely to use taste or chemical cues rather than vision to find prey.

Did your answer mention:

near its source a river or stream's channel is narrow and its current is fast
as the stream flows farther from its source the channel widens and the current slows
downstream predator vertebrates are more likely to use taste or chemical cues rather than vision to find prey

44.5 Climate and the Effects of Global Climate Change

Approximately what percentage of marine species became extinct during the Permian extinction event, about 251 million years ago?

The study of the effects of climatic conditions on the timing of periodic life-cycle events, such as flowering in plants or migration in birds, is called ________.

Describe the two named temperature anomalies that occurred during the last 2,000 years, including when each occurred and one documented effect of each.

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The Medieval Climate Anomaly occurred between 900 and 1300 AD, when slightly warmer weather conditions freed seas of ice and allowed the Vikings to colonize Greenland. The Little Ice Age was a cold period that occurred between 1550 AD and 1850 AD, during which a slight cooling of a little less than 1 °C produced exceptionally harsh winters with much snow and frost.

Did your answer mention:

the Medieval Climate Anomaly occurred between 900 and 1300 AD
slightly warmer weather conditions freed seas of ice and allowed the Vikings to colonize Greenland
the Little Ice Age was a cold period that occurred between 1550 AD and 1850 AD
a slight cooling of a little less than 1 °C produced exceptionally harsh winters with much snow and frost

Chapter 45: Population and Community Ecology

45.1 Population Demography

Which limitation of the mark and recapture method would cause scientists to underestimate a population’s size?

The number of population members divided by the area or volume being measured is called ________.

How do a population’s size and density affect its birth and death rates?

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A large population size results in a higher birth rate because more potentially reproductive individuals are present. A large population size can also result in a higher death rate because of competition, disease, and the accumulation of waste. A higher population density or a clumped dispersion pattern results in more potential reproductive encounters between individuals, which can increase birth rate.

Did your answer mention:

a large population size results in a higher birth rate because more potentially reproductive individuals are present
a large population size can also result in a higher death rate because of competition, disease, and the accumulation of waste
a higher population density or a clumped dispersion pattern results in more potential reproductive encounters between individuals, which can increase birth rate

45.2 Life Histories and Natural Selection

Which animals are given as an example of a species with few offspring and extensive parental care?

A hormonally induced physiological condition that prepares the body for successful mating, informally called “heat,” is known as the ________.

Describe the tradeoffs organisms face when reproducing early versus late in life.

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Organisms that reproduce at an early age have a greater chance of producing offspring, but this is usually at the expense of their growth and the maintenance of their health. Organisms that start reproducing later in life often have greater fecundity or are better able to provide parental care, but they risk that they will not survive to reproductive age.

Did your answer mention:

organisms that reproduce at an early age have a greater chance of producing offspring
this is usually at the expense of their growth and the maintenance of their health
organisms that start reproducing later in life often have greater fecundity or are better able to provide parental care
they risk that they will not survive to reproductive age

45.3 Environmental Limits to Population Growth

The number of organisms added to a population in each reproductive generation is called the ________.

What happens to population growth when the number of individuals in a population exceeds its carrying capacity?

How does population size behave in real-world logistic growth examples like sheep and harbor seals, compared to the idealized S-shaped curve?

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In both examples, the population size exceeds the carrying capacity for short periods of time and then falls below the carrying capacity afterwards. This fluctuation in population size continues to occur as the population oscillates around its carrying capacity. Still, even with this oscillation, the logistic model is confirmed.

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the population size exceeds the carrying capacity for short periods of time and then falls below the carrying capacity afterward
this fluctuation continues to occur as the population oscillates around its carrying capacity
even with this oscillation, the logistic model is confirmed

45.4 Population Dynamics and Regulation

Why have many population biologists abandoned or modified r- and K-selection theory?

Your response

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Over the years, several studies attempted to confirm the theory, but these attempts have largely failed. Many species were identified that did not follow the theory’s predictions. Furthermore, the theory ignored the age-specific mortality of the populations, which scientists now know is very important.

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several studies attempted to confirm the theory, but these attempts largely failed
many species were identified that did not follow the theory's predictions
the theory ignored the age-specific mortality of populations, which scientists now know is very important

In a study of the giant intestinal roundworm (Ascaris lumbricoides), denser parasite populations exhibited ________.

Regulation of a population by a factor whose effect on mortality does not depend on how dense the population is, such as weather or a natural disaster, is called ________.

45.5 Human Population Growth

Long-term exponential human population growth carries the potential risks of ________.

Age structure allows better prediction of population growth and also lets scientists associate that growth with ________.

How have countries attempted to address the environmental effects of population growth, and what has limited these efforts?

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Many countries have attempted to reduce the human impact on climate change by reducing their emission of the greenhouse gas carbon dioxide. However, these treaties have not been ratified by every country. The role of human activity in causing climate change has become a hotly debated socio-political issue in some countries, including the United States.

Did your answer mention:

many countries have attempted to reduce their emission of the greenhouse gas carbon dioxide to address climate change
these treaties have not been ratified by every country
the role of human activity in causing climate change is a hotly debated socio-political issue in some countries, including the United States

45.6 Community Ecology

The number of different species living in a habitat or biome is called ________.

Volcanoes, earthquakes, storms, fires, and climate change, whether natural or caused by human activities, are examples of a(n) ________.

How do foundation species like corals physically modify their environment to benefit other organisms?

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Foundation species may physically modify the environment to produce and maintain habitats that benefit the other organisms that use them. Corals themselves are not photosynthetic, but harbor symbionts within their body tissues (dinoflagellates called zooxanthellae) that perform photosynthesis. The exoskeletons of living and dead coral make up most of the reef structure, which protects many other species from waves and ocean currents.

Did your answer mention:

foundation species may physically modify the environment to produce and maintain habitats that benefit other organisms
corals harbor symbionts called zooxanthellae within their body tissues that perform photosynthesis
the exoskeletons of living and dead coral make up most of the reef structure, protecting other species from waves and ocean currents

45.7 Behavioral Biology: Proximate and Ultimate Causes of Behavior

The change in an organism’s activity in response to a stimulus is called ________.

What is conditioned behavior, and how does operant conditioning modify it?

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Conditioned behaviors are types of associative learning, where a stimulus becomes associated with a consequence. During operant conditioning, the behavioral response is modified by its consequences, with regards to its form, strength, or frequency.

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conditioned behaviors are types of associative learning, where a stimulus becomes associated with a consequence
during operant conditioning, the behavioral response is modified by its consequences, with regards to its form, strength, or frequency

E.O. Wilson defined sociobiology as ________.

Chapter 46: Ecosystems

46.1 Ecology of Ecosystems

Which trophic level’s organisms are usually carnivores that eat the primary consumers of a food chain?

The organism positioned at the very top of a food chain, with no higher-level consumers preying on it, is called a(n) ________.

What is a holistic ecosystem model, and why is this type of ecosystem study limited in practice?

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A holistic ecosystem model attempts to quantify the composition, interaction, and dynamics of entire ecosystems, and it is the most representative model of the ecosystem in its natural state. However, this type of study is limited by time and expense, and it is neither feasible nor ethical to do experiments on large natural ecosystems.

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a holistic ecosystem model attempts to quantify the composition, interaction, and dynamics of entire ecosystems
it is the most representative model of the ecosystem in its natural state
this type of study is limited by time and expense
it is neither feasible nor ethical to do experiments on large natural ecosystems

46.2 Energy Flow through Ecosystems

Which substance, used in coolant liquids in the United States until its use was banned in 1979, is known to biomagnify in aquatic food webs?

The rate at which photosynthetic primary producers incorporate energy from the sun is called ________.

How do photoautotrophs and chemoautotrophs differ in the energy source each uses to make its own food?

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Photoautotrophs use sunlight as their energy source. Chemoautotrophs use inorganic molecules as their energy source, and are found in ecosystems where sunlight is not available, such as dark caves or hydrothermal vents.

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photoautotrophs use sunlight as their energy source
chemoautotrophs use inorganic molecules as their energy source
chemoautotrophs are found in ecosystems where sunlight is not available, such as dark caves or hydrothermal vents

46.3 Biogeochemical Cycles

Which genus of free-living bacteria is an important nitrogen fixer, distinct from bacteria that live symbiotically in the root nodules of legumes?

The area of the Earth where water movement and storage occurs, including rivers, lakes, oceans, groundwater, and ice, is called the ________.

Why is the movement of phosphorus between the ocean and the land considered an unusually slow biogeochemical cycle?

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Phosphorus is reciprocally exchanged between phosphate dissolved in the ocean and marine ecosystems, but its movement from the ocean to the land and through the soil is extremely slow, with the average phosphate ion having an oceanic residence time between 20,000 and 100,000 years.

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phosphorus is reciprocally exchanged between phosphate dissolved in the ocean and marine ecosystems
its movement from the ocean to the land and through the soil is extremely slow
the average phosphate ion has an oceanic residence time between 20,000 and 100,000 years

Chapter 47: Conservation Biology and Biodiversity

47.1 The Biodiversity Crisis

Which of the following is one of the three human activities blamed for today’s accelerated species loss, unlike the causes of the five previous mass extinctions?

A geographical region containing high numbers of endemic species along with a large percentage of degraded habitat, a conservation concept originated by Norman Myers in 1988, is called a ________.

What are three hypotheses proposed to explain why species biodiversity increases as latitude declines toward the equator?

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One hypothesis is that ecosystems in the tropics are older, and greater age provides more time for speciation. Another possible explanation is that the tropics receive more direct energy from the sun than temperate and polar regions. A third hypothesis is that greater habitat heterogeneity, or number of ecological niches, in the tropics provides more opportunities for coevolution and specialization, promoting speciation.

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ecosystems in the tropics are older, and greater age provides more time for speciation
the tropics receive more direct energy from the sun than temperate and polar regions
greater habitat heterogeneity, or number of ecological niches, in the tropics provides more opportunities for coevolution and specialization

47.2 The Importance of Biodiversity to Human Life

It is estimated that, at one time, what percentage of modern drugs contained at least one plant extract?

Aquatic resources provide the main source of animal protein for about how many people worldwide?

According to entomologist E. O. Wilson, why do city environments harm human well-being, and what does this suggest about biodiversity’s value to humans?

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Wilson argues that human evolutionary history has adapted humans to live in a natural environment, and that city environments generate psychological stressors that affect human health and well-being; this suggests humans benefit psychologically from living in a biodiverse world.

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human evolutionary history has adapted humans to live in a natural environment
city environments generate psychological stressors that affect human health and well-being
humans benefit psychologically from living in a biodiverse world

47.3 Threats to Biodiversity

About what percentage of the timber imported into the United States is estimated to be potentially illegally logged?

The invasive plant species native to Japan, introduced to the United States in 1876 for soil conservation, and now covering over 7 million acres in the southeastern United States, is called ________.

Explain why polar bears and grizzly bears, which historically had separate ranges, are now sometimes producing hybrid offspring, and name the hybrid.

Your response

Show model answer

As climate change causes warming trends to shift colder climates toward the poles, grizzly bear habitat now overlaps polar bear habitat in the Arctic. Because these two species are capable of mating and producing viable offspring, in 2006 a hunter shot a wild grizzly-polar bear hybrid known as a grolar bear, the first wild hybrid ever found.

Did your answer mention:

grizzly bear habitat now overlaps polar bear habitat in the Arctic
these two species are capable of mating and producing viable offspring
in 2006 a hunter shot a wild grizzly-polar bear hybrid known as a grolar bear, the first wild hybrid ever found

47.4 Preserving Biodiversity

As of mid-2017, about how many named species had been identified through DNA barcoding?

The non-profit organization that monitors illegal wildlife trade internationally is known by which abbreviation?

According to the theory of island biogeography, why do islands farther from the mainland, and islands that are smaller, tend to support fewer species?

Your response

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Islands farther from a mainland are harder to get to, so migration is lower and the equilibrium number of species is lower. Smaller islands are also harder to find, so their immigration rates for new species are typically lower, and because they are less geographically diverse they have fewer niches to promote speciation; smaller islands also support smaller populations, so the probability of extinction is higher.

Did your answer mention:

islands farther from a mainland are harder to get to, so migration is lower and the equilibrium number of species is lower
smaller islands are harder to find, so their immigration rates for new species are typically lower
smaller islands support smaller populations, so the probability of extinction is higher

This knowledge check is written for Unit 8 (Chapters 44–47) of Biology 2e by Mary Ann Clark, Jung Choi, Matthew Douglas, and OpenStax, © OpenStax, licensed under CC BY-NC-SA 4.0. Access the original for free at openstax.org. Changes: every question is locally written from the pinned text of the chapters’ own modules — their section summaries, glossary definitions, body passages, and comparison tables — and none is transcribed from the book’s exercise sets, which the section pages already carry; no question carries a hint, and every self-check carries a rubric that decomposes a model answer made of the module’s own sentences.

Preserving Biodiversity