50-54 Flashcards
CONCEPT: Sensory receptors transduce stimulus energy and transmit signals to the central nervous system
(pp. 1085–1090) - Sensory receptors - sensory transduction - transmission - Mechanoreceptors - Chemoreceptors - Electromagnetic receptors - thermoreceptors - nociceptors
Sensory receptors
are usually specialized neurons or epithelial cells that detect external or internal stimuli
sensory transduction
The detection of a stimulus by sensory cells precedes sensory transduction, the change in the membrane potential of a sensory receptor in response to a stimulus
transmission
The resulting receptor potential controls transmission of action potentials to the CNS, where sensory information is integrated to generate perceptions
stimulus strength.
The frequency of action potentials in an axon and the number of axons activated determine stimulus strength
five basic types of sensory receptors
Mechanoreceptors: respond to stimuli such as pressure, touch, stretch, motion, and sound. Chemoreceptors: detect either total solute concentrations or specific molecules. Electromagnetic receptors: detect different forms of electromagnetic radiation. Thermoreceptors signal: surface and core temperatures of the body Nociceptors: Pain is detected by a group of nociceptors that respond to excess heat, pressure, or specific classes of chemicals
CONCEPT: The mechanoreceptors responsible for hearing and equilibrium detect moving fluid or settling particles
(pp. 1090–1094) • Most invertebrates sense their orientation with respect to gravityby means of statocysts. Specialized hair cells form thebasis for hearing and balance in mammals and for detection of water movement in fishes and aquatic amphibians. In mammals, the tympanic membrane (eardrum) transmits sound waves to three small bones of the middle ear, which transmit the waves through the oval window to the fluid in the coiled cochlea of the inner ear. Pressure waves in the fluid vibrate the basilar membrane, depolarizing hair cells and triggering action potentials that travel via the auditory nerve to the brain. Each region of the basilar membrane vibrates most vigorously at a particular frequency and leads to excitation of a specific auditory area of the cerebral cortex. Receptors in the inner ear function in balance and equilibrium.
Statocysts.
Most invertebrates sense their orientation with respect to gravity by means of statocysts. Specialized hair cells form the basis for hearing and balance in mammals and for detection of water movement in fishes and aquatic amphibians
Tympanic membrane
In mammals, the tympanic membrane (eardrum) transmits sound waves to three small bones of the middle ear, which transmit the waves through the oval window to the fluid in the coiled cochlea of the inner ear.
basilar membrane
Pressure waves in the fluid vibrate the basilar membrane, depolarizing hair cells and triggering action potentials that travel via the auditory nerve to the brain. Each region of the basilar membrane vibrates most vigorously at a particular frequency and leads to excitation of a specific auditory area of the cerebral cortex. Receptors in the inner ear function in balance and equilibrium.
CONCEPT Visual receptors in diverse animals depend on light-absorbing pigments
(pp. 1095–1101) • Invertebrates have varied light detectors, including simple lightsensitive eyespots, image-forming compound eyes, and singlelens eyes. In the vertebrate eye, a single lens is used to focus light on photoreceptors in the retina. Both rods and cones contain a pigment, retinal, bonded to a protein (opsin). Absorption of light by retinal triggers a signal transduction pathway that hyperpolarizes the photoreceptors, causing them to release less neurotransmitter. Synapses transmit information from photoreceptors to cells that integrate information and convey it to the brain along axons that form the optic nerve.
CONCEPT The senses of taste and smell rely on similar sets of sensory receptors
(pp. 1101–1103) Both taste (gustation) and smell (olfaction) depend on the stimulation of chemoreceptors by small dissolved molecules that bind to proteins on the plasma membrane. In humans, sensory cells within taste buds express a single receptor type specific for one of the five taste perceptions—sweet, sour, salty, bitter, and umami (elicited by glutamate). Olfactory receptor cells line the upper part of the nasal cavity and extend axons to the olfactory bulb of the brain. More than 1,000 genes code for membrane proteins that bind to specific classes of odorants, and each receptor cell appears to express only one of those genes.
CONCEPT The physical interaction of protein filaments is required for muscle function
(pp. 1103–1110) The muscle cells (fibers) of vertebrate skeletal muscle contain myofibrils composed of thin filaments of (mostly) actin and thick filaments of myosin. Motor neurons release acetylcholine, triggering action potentials that penetrate the muscle fiber along the T tubules and stimulate the release of Ca2 from the sarcoplasmic reticulum. When the Ca2 binds the troponin complex, tropomyosin repositions on the thin filaments, exposing the myosin-binding sites on actin and thus initiating cross-bridge formation. A motor unit consists of a motor neuron and the muscle fibers it controls. Recruiting multiple motor units results in stronger contractions. A twitch results from a single action potential in a motor neuron. Cardiac muscle, found only in the heart, consists of striated cells that are electrically connected by intercalated disks and that can generate action potentials without input from neurons.
CONCEPT Skeletal systems transform muscle contraction into locomotion
(pp. 1110–1115) Skeletal muscles, often in antagonistic pairs, bring about movement by contracting and pulling against the skeleton. Skeletons may be hydrostatic and maintained by fluid pressure, as in worms; hardened into exoskeletons, as in insects; or in the form of endoskeletons, as in vertebrates. • Each form of locomotion—swimming, movement on land, or flying—presents a particular challenge. For example, swimmers need to overcome friction, but face less of a challenge from gravity than do animals that move on land or fly. Animals specialized for swimming expend less energy per distance traveled than similarly sized animals specialized for flying or running. For any of the three major modes of locomotion, larger animals are more efficient than smaller ones.
50:1 test Which of the following sensory receptors is incorrectly paired with its category? a. hair cell—mechanoreceptor b. muscle spindle—mechanoreceptor c. taste receptor—chemoreceptor d. rod—electromagnetic receptor e. olfactory receptor—electromagnetic receptor
e
50:1 test The middle ear converts a. air pressure waves to fluid pressure waves. b. fluid pressure waves to air pressure waves. c. air pressure waves to nerve impulses. d. fluid pressure waves to nerve impulses. e. pressure waves to hair cell movements.
a
50:1 test During the contraction of a vertebrate skeletal muscle fiber, calcium ions a. break cross-bridges by acting as a cofactor in the hydrolysis of ATP. b. bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed. c. transmit action potentials from the motor neuron to the muscle fiber. d. spread action potentials through the T tubules. e. re-establish the polarization of the plasma membrane following an action potential.
b
50:2 test Which sensory distinction is not encoded by a difference in neuron identity? a. white and red d. salty and sweet b. red and green e. spicy and cool c. loud and faint
c
50:2 test The transduction of sound waves into action potentials takes place: a. within the tectorial membrane as it is stimulated by the hair cells. b. when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neurons. c. as the basilar membrane becomes more permeable to sodium ions and depolarizes, initiating an action potential in a sensory neuron. d. as the basilar membrane vibrates at different frequencies in response to the varying volume of sounds. e. within the middle ear as the vibrations are amplified by the malleus, incus, and stapes.
b
50:3 test Although some sharks close their eyes just before they bite, their bites are on target. Researchers have noted that sharks often misdirect their bites at metal objects and that they can find batteries buried under sand. This evidence suggests that sharks keep track of their prey during the split second before they bite in the same way that: a. a rattlesnake finds a mouse in its burrow. b. a male silkworm moth locates a mate. c. a bat finds moths in the dark. d. a platypus locates its prey in a muddy river. e. a flatworm avoids light places.
d
CONCEPT Earth’s climate varies by latitude and season and is changing rapidly
(pp. 1144–1150) • Global climate patterns are largely determined by the input of solar energy and Earth’s revolution around the sun. • The changing angle of the sun over the year, bodies of water, and mountains exert seasonal, regional, and local effects on macroclimate. •Fine-scale differences in abiotic (nonliving) factors, such as sunlight and temperature, determine microclimate. • Increasing greenhouse gas concentrations in the air are warming Earth and altering the distributions of many species. Some species will not be able to shift their ranges quickly enough to reach suitable habitat in the future.
climate
Global climate patterns are largely determined by the input of solar energy and Earth’s revolution around the sun.
macroclimate.
changing angle of the sun over the year, bodies of water, and mountains exert seasonal, regional, and local effects
abiotic
abiotic (nonliving) factors. Fine-scale differences in abiotic (nonliving) factors, such as sunlight and temperature, determine microclimate.
Suppose global air circulation suddenly reversed, with most air ascending at 30° north and south latitude and descending at the equator. At what latitude would you most likely find deserts in this scenario?
Because dry air would descend at the equator instead of at 30° north and south latitude (where deserts exist today), deserts would be more likely to exist along the equator (see Figure 52.3
CONCEPT The structure and distribution of terrestrial biomes are controlled by climate and disturbance
(pp. 1150–1156) • Climographs show that temperature and precipitation are correlated with biomes. Because other factors also play roles in biome location, biomes overlap. • Terrestrial biomes are often named for major physical or climatic factors and for their predominant vegetation. Vertical layering is an important feature of terrestrial biomes. • Disturbance, both natural and human-induced, influences the type of vegetation found in biomes. Humans have altered much of Earth’s surface, replacing the natural terrestrial communities described and depicted in Figure 52.12 with urban and agricultural ones.
Climographs
show that temperature and precipitation are correlated with biomes
biomes
?? Because other factors also play roles in biome location, biomes overlap.
Terrestrial biomes
are often named for major physical or climatic factors and for their predominant vegetation. Vertical layering is an important feature of terrestrial biomes
Disturbance
both natural and human-induced, influences the type of vegetation found in biomes. Humans have altered much of Earth’s surface, replacing the natural terrestrial communities described and depicted in Figure 52.12 with urban and agricultural ones.
CONCEPT Aquatic biomes are diverse and dynamic systems that cover most of Earth
(pp. 1157–1163) •Aquatic biomes are characterized primarily by their physical environment rather than by climate and are often layered with regard to light penetration, temperature, and community structure. Marine biomes have a higher salt concentration than freshwater biomes. • In the ocean and in most lakes, an abrupt temperature change called a thermocline separates a more uniformly warm upper layer from more uniformly cold deeper waters.
Aquatic biomes
characterized primarily by their physical environment rather than by climate and are often layered with regard to light penetration, temperature, and community structure. Marine biomes have a higher salt concentration than freshwater biomes.
Thermocline
an abrupt temperature change separating a more uniformly warm upper layer from more uniformly cold deeper waters
In which aquatic biomes might you find an aphotic zone?
An aphotic zone is most likely to be found in the deep waters of a lake, the oceanic pelagic zone, or the marine benthic zone.
CONCEPT Interactions between organisms and the environment limit the distribution of species
(pp. 1163–1167) Ecologists want to know not only where species occur but also why those species occur where they do. The distribution of species may be limited by dispersal, the movement of individuals away from their area of origin; behavior; biotic (living) factors; and abiotic factors, such as temperature extremes, salinity, and water availability.
dispersal
the movement of individuals away from their area of origin;
52:1 TEST Which of the following areas of study focuses on the exchange of energy, organisms, and materials between ecosystems? a. population ecology b. organismal ecology c. landscape ecology d. ecosystem ecology e. community ecology
c
52:1 TEST Which lake zone would be absent in a very shallow lake? a. benthic zone b. aphotic zone c. pelagic zone d. littoral zone e. limnetic zone
b
52:1 TEST Which of the following is true with respect to oligotrophic lakes and eutrophic lakes? a. Oligotrophic lakes are more subject to oxygen depletion. b. Rates of photosynthesis are lower in eutrophic lakes. c. Eutrophic lake water contains lower concentrations of nutrients. d. Eutrophic lakes are richer in nutrients. e. Sediments in oligotrophic lakes contain larger amounts of decomposable organic matter.
d
52:1 TEST Which of the following biomes is correctly paired with the description of its climate? a. savanna—low temperature, precipitation uniform during the year b. tundra—long summers, mild winters c. temperate broadleaf forest—relatively short growing season, mild winters d. temperate grasslands—relatively warm winters, most rainfall in summer e. tropical forests—nearly constant day length and temperature
e
52:2 TEST Which of the following is characteristic of most terrestrial biomes? a. annual average rainfall in excess of 250 cm b. a distribution predicted almost entirely by rock and soil patterns c. clear boundaries between adjacent biomes d. vegetation demonstrating vertical layering e. cold winter months
d
52:2 TEST The oceans affect the biosphere in all of the following ways except a. producing a substantial amount of the biosphere’s oxygen. b. removing carbon dioxide from the atmosphere. c. moderating the climate of terrestrial biomes. d. regulating the pH of freshwater biomes and terrestrial groundwater. e. being the source of most of Earth’s rainfall
d
52:2 TEST Which statement about dispersal is false? a. Dispersal is a common component of the life cycles of plants and animals. b. Colonization of devastated areas after floods or volcanic eruptions depends on dispersal. c. Dispersal occurs only on an evolutionary time scale. d. Seeds are important dispersal stages in the life cycles of most flowering plants. e. The ability to disperse can expand the geographic distribution of a species.
c
52:2 TEST When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes a. in biomes at different latitudes. b. at different depths in the ocean. c. in a community through different seasons. d. in an ecosystem as it evolves over time. e. across the United States from east to west.
a
52:2 TEST Suppose that the number of bird species is determined mainly by the number of vertical strata found in the environment. If so, in which of the following biomes would you find the greatest number of bird species? a. tropical rain forest b. savanna c. desert d. temperate broadleaf forest e. temperate grassland
a
52:3 TEST If the direction of Earth’s rotation reversed, the most predictable effect would be a. no more night and day. b. a big change in the length of the year. c. winds blowing from west to east along the equator. d. a loss of seasonal variation at high latitudes. e. the elimination of ocean currents.
c
CONCEPT Discrete sensory inputs can stimulate both simple and complex behaviors
(pp. 1118–1122) • Behavior is the sum of responses to external and internal stimuli and includes muscular as well as nonmuscular activity. Tinbergen developed a set of questions that highlight the complementary nature of two perspectives. Proximate, or “how,” questions focuson the environmental stimuli, if any, that trigger a behavior, as well as the genetic, physiological, and anatomical mechanisms underlying a behavioral act. Ultimate, or “why,” questions address the evolutionary significance of a behavior. • A fixed action pattern is a largely invariant behavior triggered by a simple cue known as a sign stimulus. Migratory movements involve navigation, which can be based on orientation relative to the sun, the stars, or Earth’s magnetic field. Animal behavior is sometimes synchronized to the daily, or circadian, cycle of light and dark in the environment or to environmental cues that cycle over the seasons. • The transmission and reception of signals constitute animal communication. Animals use visual, auditory, chemical (usually olfactory), and tactile signals, sometimes as part of a stimulus-response chain that governs a complex behavior. Chemical substances called pheromones transmit species-specific information through the environment in behaviors ranging from foraging to courtship.
Behavior
the sum of responses to external and internal stimuli and includes muscular as well as nonmuscular activity
fixed action pattern
a largely invariant behavior triggered by a simple cue known as a sign stimulus
animal communication
The transmission and reception of signals constitute animal communication. Animals use visual, auditory, chemical (usually olfactory), and tactile signals, sometimes as part of a stimulus-response chain that governs a complex behavior
How is migration based on circannual rhythms poorly suited for adaptation to global climate change?
Circannual rhythms are typically based on the cycles of light and dark in the environment. As the global climate changes, animals that migrate in response to these rhythms may shift to a location before or after local environmental conditions are optimal for reproduction and survival.
CONCEPT Learning establishes specific links between experience and behavior
(pp. 1123–1128) Cross-fostering studies can be used to measure the influence of social environment and experience on behavior. • Learning, the modification of behavior based on experience, can take many forms: Imprinting, cognition, spatial learning, associative learning, social learning
Imprinting
?
cognition
?
spatial learning
?
associative learning
?
social learning
?
How do imprinting in geese and song development in sparrows differ with regard to the resulting behavior?
For the goose, all that is acquired is an object at which the behavior is directed. In the case of the sparrow, learning takes place that will give shape to the behavior itself.
CONCEPT Selection for individual survival and reproductive success can explain most behaviors
(pp. 1128–1134) • An optimal foraging model is based on the idea that natural selection should favor foraging behavior that minimizes the costs of foraging and maximizes the benefits. • Sexual dimorphism correlates with the type of mating relationship between males and females. These include monogamous and polygamous mating systems. Variation in mating system and variation in the mode of fertilization affect certainty of paternity, which in turn has a significant influence on mating behavior and parental care. • Game theory provides a way of thinking about evolution in situations where the fitness of a particular behavioral phenotype is influenced by other behavioral phenotypes in the population.
optimal foraging model
based on the idea that natural selection should favor foraging behavior that minimizes the costs of foraging and maximizes the benefits
monogamous
?? Sexual dimorphism correlates with the type of mating relationship between males and females.
53:2
According to the logistic growth equation
a. the number of individuals added per unit time is greatest
when N is close to zero.
b. the per capita growth rate (r) increases as N approaches K.
c. population growth is zero when N equals K.
d. the population grows exponentially when K is small.
e. the birth rate (b) approaches zero as N approaches K.
c
Competition (-/-)
Two or more species compete for a resource
that is in short supply.
Another important species in the Chesapeake Bay estuary (see Figure 54.15) is the blue crab (Callinectes sapidus). It is an omnivore, eating eelgrass and other primary producers as well as clams. It is also a cannibal. In turn, the crabs are eaten by humans and by the endangered Kemp’s Ridley sea turtle. Based on this information, draw a food web that includes the blue crab. Assuming that the top-down model holds for this system, what would happen to the abundance of eelgrass if humans stopped eating blue crabs?
