27) How do muscle fibers shorten during contraction?

14) At a chemical synapse, what causes the ion channels on the receiving cell's membrane to open?

11) Why are action potentials usually conducted in one direction?

Exam 4 – Fall 15 Name________Key__________ Biology 151 – General Biology II 150 Points Total Use your scantron sheet for questions #1-50. Multiple Choice - 2 points each 1) The two primary cell types of the nervous system are _______ and _______. A)We also discuss several other topics like scsu accounts receivable
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fibroblasts; chondrocytes B) neurons; glial cells C) epithelial cells; glandular cells D) neurons; epithelial cells E) neuromuscular cells; epithelial cells 2) Which of the following is not one of the functions of glial cells? A) Supporting neurons during embryonic development B) Supplying nutrients C) Conducting nerve impulses D) Consuming foreign particles E) Insulating nerve tissue 3) Which one of the following statements about neurons is true?  A) Axons carry signals toward the cell body.  B) The myelin sheath houses the dendrites.  C) Nodes of Ranvier help to convey signals toward the cell body.  D) Dendrites relay signals to another neuron or an effector, such as a muscle cell.  E) The cell body houses the neuron's nucleus and most of its organelles. 4) The area where two neurons come into close contact with each other and pass along information A) is nearly always in a ganglion. B) differs with different types of neurons. C) is called a synapse. D) is at the node of Ranvier. E) is located in the middle of the neurons. 5) Which of the following can carry electric charges across the cell membrane? A) Electrons B) Protons C) Water D) Ions E) Proteins 6) The minimum change in a membrane's voltage that must occur to trigger an action potential is the  _____.  A) triggering charge  B) voltage potential  C) minimum voltage  D) threshold voltage E) triggering voltage 1 7) Once an action potential is triggered, the first major chemical change is  A) a reversal of the membrane polarity, with the interior of the neuron becoming negative. B) propagation of an impulse across nodes of Ranvier. C) an increase in the positive charge outside the neuron. D) a reversal of the membrane polarity, with the interior of the neuron becoming positive. E) an increase in the negative charge inside the neuron. 8) The creation of the resting potential of a neuron is due mostly to A) local current spread. B) open Na+ channels. C) synaptic summation. D) closed K+ channels. E) Na+/K+ ion pumps. 9) The falling phase of an action potential is due to the A) closing of K+ channels. B) opening of chemically-gated Na+ channels. C) closing of voltage-gated Ca2+ channels. D) opening of voltage-gated K+ channels. E) spread of positive current along the plasma membrane. 10) For a neuron with an initial membrane potential at -70 mV, an increase in the movement of  potassium ions out of that neuron's cytoplasm would result in A) the depolarization of the neuron. B) the replacement of potassium ions with sodium ions. C) the neuron switching on its sodium-potassium pump to restore the initial conditions. D) the replacement of potassium ions with calcium ions. E) the hyperpolarization of the neuron. 11) Why are action potentials usually conducted in one direction? A) The nodes of Ranvier conduct potentials in one direction. B) The brief refractory period prevents reopening of voltage-gated Na+ channels. C) The axon hillock has a higher membrane potential than the terminals of the axon. D) Ions can flow along the axon in only one direction. E) Voltage-gated channels for both Na+ and K+ open in only one direction. 12) When an action potential arrives at the axon terminal, the voltage-gated calcium channels at the  terminal A) release calcium into the synaptic cleft. B) actively transport neurotransmitter into the synaptic cleft. C) open; the influx of calcium causes the vesicles to fuse with the presynaptic membrane and release  a neurotransmitter into the synaptic cleft. D) depolarize the membrane at the axon terminal. E) cause the membrane receptors to bind the neurotransmitter. 13) Neurotransmitters are released from axon terminals via A) exocytosis. B) active transport. C) transcytosis. D) osmosis. E) diffusion.2 14) At a chemical synapse, what causes the ion channels on the receiving cell's membrane to open?  A) The neurotransmitters create an electrical charge on their own.  B) An electrical spark transfers between the neurons.  C) The neurotransmitter binds to a ligand gated ion channel causing it to open.  D) The synaptic cleft pinches together, squeezing the channels open.  E) Neurotransmitters rush out of the receiving cell, causing the channel to open.  15) As you prepare to head off to class, you reach up to grab a pencil, but poke the tip of your finger.  Quickly, and without thinking, you pull your hand back. Which of the following is the correct sequence  of neuronal action involved in this reflexive response?  A) sensory neuron, interneuron, motor neuron B) interneuron, sensory neuron, motor neuron  C) sensory neuron, motor neuron, interneuron  D) motor neuron, interneuron, sensory neuron  E) motor neuron, sensory neuron, interneuron  16) 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 17) The magnitude of a receptor potential A) depends on the strength of the incoming action potential. B) remains high even after a long period of stimulation. C) is the same no matter what the type of stimulus. D) depends on the amount of neurotransmitter released. E) affects the frequency of resulting action potentials. 18) Immediately after putting on a shirt, your skin feels itchy. However, the itching stops after a few  minutes and you are unaware that you are wearing a shirt. Why?  A) Perception has increased.  B) Sensory adaptation has occurred. C) Transduction has increased.  D) Receptor amplification has decreased.  E) Motor unit recruitment has decreased.  19) Which one of the following statements about the vertebrate eye is true? A) Schwann cells conduct action potentials to the brain.  B) The eye's photoreceptors are located in the choroid of the eye.  C) The lens is the transparent part of the sclera that lets light into the eye.  D) The cornea contains muscles that make the pupil smaller or larger.  E) The optic nerve leaves the eye at the blind spot. 20) Which of the following components of the human eye forms the iris?  A) pupil  B) choroid  C) sclera  D) retina  E) vitreous humor 3 21) The color in color vision results from the  A) ability of all cones cells to absorb all wavelengths of light equally. B) lens of the eye acting like a prism and separating the different wavelengths of light. C) differential absorption of wavelengths of light by different kinds of rod cells. D) three different opsin proteins in cone cells. E) absorption of different wavelengths of light by amacrine and horizontal cells. 22) Hair cells in the ear that give auditory information are concentrated in the A) oval window. B) tympanic membrane. C) organ of Corti. D) semicircular canals. E) vestibular apparatus. 23) Which of the following structures of the mammalian auditory system is responsible for transmitting  signals between the flexible tympanic and oval window membranes? A) Organ of Corti B) Ear ossicles C) Pinnae D) Cochlea E) Semicircular canals 24) Which of the following sensory structures provides mammals with information about the position  and orientation of the head? A) Eustachian tube B) Cochlea C) Semicircular canal D) Lateral line E) Tympanic membrane 25) The middle ear converts A) air pressure waves to fluid pressure waves. B) fluid pressure waves to air pressure waves. C) fluid pressure waves to nerve impulses D) air pressure waves to nerve impulses. E) pressure waves to hair cell movements. 26) The striated appearance of skeletal muscle is due to the A) dark color of myosin. B) multiple nuclei per fiber. C) regular arrangement of filaments. D) dense array of microtubules. E) dense packing of ATP molecules. 27) How do muscle fibers shorten during contraction? A) Individual protein filaments contract. B) More cross-bridges are formed between filaments. C) Arrays of filaments overlap each other. D) Protein filaments coil more tightly. E) Subunits of protein polymers detach.4 28) A thick filament consists of ______.  A) actin and myosin  B) actin and regulatory proteins  C) actin  D) myosin and regulatory filaments  E) myosin  29) How do actin and myosin molecules interact? A) Globular myosin heads bind to actin filaments. B) Globular actin heads bind to myosin filaments. C) Other proteins connect the two. D) Myosin filaments bend to connect to actin. E) Actin filaments bend to connect to myosin. 30) What is the role of the sarcoplasmic reticulum in muscle contraction? A) It stores Ca2+ ions for release during contraction. B) It surrounds and protects the muscle filaments. C) It provides sites of ATP synthesis. D) It depolarizes when stimulated by an impulse. E) It synthesizes actin and myosin filaments. 31) How does tropomyosin control muscle contraction? A) It provides a bridge between actin and myosin. B) It provides a site where ATP can be utilized. C) Changes in its position expose actin–myosin binding sites. D) It transmits electric charge to the filaments. E) Changes in its shape open membrane channels. 32) Which of the following levels of organization is arranged in the correct sequence from least to  most inclusive?  A) population, ecosystem, individual, community  B) individual, community, population, ecosystem  C) community, ecosystem, population, individual  D) community, ecosystem, individual, population  E) individual, population, community, ecosystem 33) Organismal ecology is best described as the study of  A) the flow of energy and materials between the biotic and abiotic components of an ecosystem.  B) how the structure and function of species enable them to meet the challenges of their environment. C) the interactions between the different species that inhabit an ecosystem.  D) the factors controlling the exchanges of energy, materials, and organisms among ecosystem  patches.  E) what factors affect the structure and size of a population over time. 5 34) Ecosystem ecology is best described as the study of  A) what factors affect the structure and size of a population over time.  B) the factors controlling the exchanges of energy, materials, and organisms among ecosystem  patches.  C) how the structure and function of species enable them to meet the challenges of their  environment.  D) the interactions between the different species that inhabit an ecosystem.  E) the flow of energy and materials between the biotic and abiotic components of an ecosystem. 35) What is the primary source of energy for nearly all of Earth's ecosystems?  A) temperature  B) geothermal vents  C) sunlight D) rocks and soil  E) wind  36) The long-term average atmospheric conditions of a region is referred to as its A) weather. B) biotic factor. C) biome. D) community. E) climate. 37) The number of individuals of a population per unit area is the ______.  A) population dispersion pattern  B) population density C) population's intrinsic rate of increase  D) population size  E) population age structure  38) Suppose seedlings of a plant emit a chemical that reduces the growth of other individuals around  them. This would most likely result in the plants having a _______ dispersion pattern. A) random B) cohort C) clumped D) uniform E) logistic 39) In the absence of limiting factors, what shape does a population's growth curve most closely  resemble?  A) ∧ B) S  C) ∩  D) J 40) In the presence of limiting factors, a population's growth follows a(n) ______ model.  A) geometric  B) hypergeometric  C) exponential  D) logistic E) mathematical 6 41) We would expect populations to grow close to or at their intrinsic rate of growth when A) they are near their environmental carrying capacity. B) their numbers are low. C) they have depleted their food supply. D) density-dependent factors are reducing birth rates. E) Both a and c 42) Which of the following types of survivorship curves best describes humans living in the  contemporary United States? A) Type I B) Type II C) Type III D) logistic growth E) exponential growth  43) Which of these best describes Type III survivorship?  A) low death rate during the prereproductive years, high death rate during the reproductive years, low  death rate during the postreproductive years  B) high death rate during the prereproductive years, low death rate during the reproductive years,  high death rate during the postreproductive years  C) low death rate during the prereproductive and reproductive years, high death rate during the  postreproductive years  D) very high death rate very early in life followed by a decline in death rate E) relatively constant death rate throughout the life span  44) Which of the following statements is an example of a density-independent effect? A) The number of nests in an area is limited to 70. B) The incidence of malaria increases as populations increase. C) Drought kills seedlings. D) Large aggregations of guppies attract predators. E) None of the above 45) The species that live and interact in a given area constitute an ecological A) biome. B) family. C) food web. D) community. E) trophic level. 46) Which of the following statements is consistent with the principle of competitive exclusion?  A) The density of one competing species will have a positive impact on the population growth of the  other competing species.  B) Two species with the same fundamental niche will exclude other competing species.  C) Bird species generally do not compete for nesting sites.  D) Evolution tends to increase competition between related species.  E) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted  of two competing species.7 47) Which of the following is an example of cryptic coloration?  A) bands on a coral snake  B) brown color of tree bark  C) a "walking stick" insect that resembles a twig D) colors of an insect-pollinated flower  E) bright markings of a viceroy butterfly 48) Which of the following is an example of a mutualistic interaction? A) Barnacles obtain safe haven by riding on a whale, while the whale is unaffected. B) A bacterium fixes nitrogen, thereby providing nutrient for a plant, while the plant provides  protection for the bacterium. C) A virus infects a bird, thus reducing the bird’s fecundity. D) Both a and b E) None of the above 49) Which of the following statements about communities is false? A) They can vary tremendously in size and scope. B) An important factor in determining their species richness is the amount of energy available. C) Energy enters communities through primary consumers. D) An ecological community comprises a group of species that coexist and interact within a defined  area. E) All of the above are true; none are false. 50) Organisms at the first trophic level are ______.  A) decomposers  B) parasites  C) predators  D) detritivores  E) autotrophs8 Answer directly on the exam for questions #51 – 54 Short Answer Essays: For questions 51 – 53 provide a short answer to the question (1+ complete sentences). Single word or short phrase answers will not receive full credit. You may use drawings as  part of your answer. 51. (15 points total) Sensory Systems a. (10 points) Compare and contrast the functioning of chemoreceptors and photoreceptors.  One similarity between chemoreceptors and photoreceptors Chemoreceptors and photoreceptors are protein molecules found on sensory cells that receive  specific sensory signals. After receiving a signal both of these proteins initiate a transduction pathway  that transmit information about the signal into the receptor cell eliciting a receptor potential. Most of  the chemoreceptors and photoreceptors in humans are 7 pass transmembrane G protein coupled  receptors. One difference between chemoreceptors and photoreceptors Chemoreceptors are located in the taste buds and olfactory epithelium of humans whereas the  photoreceptors are found in the retina of the eye. Chemoreceptors receive chemical signals and  photoreceptors receive light signals. Chemoreceptor proteins have a specific extracellular surface for  receiving the chemical signal. Photoreceptors contain retinol that changes shape upon reception of  the photon of light. b. (5 points) Amplification of signal is an important feature of sensory systems. Provide one example of the amplification mechanism of visual or auditory systems: The lens of the eye focuses the light that enters the pupil onto the small fovea area at the back of the  eye where most of the photoreceptors cell reside. Similarly. The ossicle bones in the middle ear focus  the energy from the pressure waves of sound on to the oval window creating fluid waves in the  cochlea.9 52. (15 points total) Population Ecology a. (5 points) Where is exponential growth by a plant population more likely – in an area where a forest  was destroyed by fire or in a mature, undisturbed forest? Why? Exponential growth is more likely in the area where a forest was destroyed by fire. The first plants that  found suitable habitat there would encounter an abundance of space, nutrients, and light. In the  undisturbed forest, competition among plants for these resources would be intense. b. (10 points) Explain why a population that fits the logistic growth model (like your duckweed in lab)  increases more rapidly at intermediate size than at relatively small and large sizes. Refer to the figure  of a logistic growth curve from your book below for assistance. When N (population size) is small, there are relatively few individuals producing offspring. When N is  large, near the carrying capacity, the per capita growth rate is relatively small because it is limited by  available resources. The steepest part of the logistic growth curve corresponds to a population with a  number of reproducing individuals that is substantial but not yet near carrying capacity.10 53. (20 points total) Community Ecology a. (10 points) Explain how interspecific competition, predation, and mutualism differ (you need to write  about all three below) in their effects on the interacting populations of two species. Interspecific competition has negative effects on both species (-/-). In predation, the predator  population benefits at the expense of the prey population (+/-). Mutualism is a symbiosis in which both  species benefit (+/+). b. (10 points) According to the principle for competitive exclusion, what outcome is expected when  two species with identical niches compete for a resource? Why? One of the competing species will become locally extinct because of the greater reproductive success  of the more efficient competitor11