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81 Cards in this Set
- Front
- Back
Why was the idea that fiossils were the remnants of ancient forms of life developed?
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1. fossils were found throughout the world
2. fossils resembled living organisms 3.unique fossils were found in specific layers of stratified rocks 4. fossils could be used to study past geologic events |
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Does macroevolution refer to changes in species?
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no
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Would you expect to find a shelled arthropod such as a trilobite preserved as a fossil?
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yes
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Would a bed of a former shallow sea be a habitat that you would be likely to find fossils in?
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yes
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What is the convergence in external morphology of sharks, penguins, and porpoises attributed to?
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selection pressures that are common to these groups
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Sharks, penguins and porpoises serve as examples of what kind of convergence?
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morphological
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Would early reptiles be considered more or less primitive than bats, porpoises, penguins, and birds?
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more primitive, based upon the structure of their limbs
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the bones in the forelimbs of a mammal can often be traced to what?
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a common ancestor
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are the wing of a bird and the wing of a butterfly analogous to each other? homologous?
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analyogous but not homologous
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How did the variation in the forms of adult vertebrates arise?
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probably through mutations in regulatory genes
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what is the most conclusive evidence used in establishing the relationship of closely related species?
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nucleic acid and hybridization
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according to astronomers is the universe expanding?
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yes
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the "big bang" refers to what?
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an event marking the beginning of the universe
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how old is the solar system?
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about 4.6 - 5 billion years old
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fossil evidence of the earliest living organisms dates back how far?
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3.8 billion years
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How long ago did life on earth begin?
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3,800,000,000 years ago...?
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Did the primitive earth's atmosphere contain free oxygen?
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no
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would the organic compounds essential for life, such as amino acids and nucleotides be able to assemble spontaneously in the presence of free oxygen?
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it is doubtful
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how is the earth able to maintain water in a liquid state on its surface?
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by virtue of the distance of the earth from the sun and the size of the earth
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how did the early atmosphere of the earth originate?
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when gases from beneath te slowly solidifying crust were vented by vulcanism
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Experiments by who demonstrated that many of the lipids, carbs, proteins, and nucleotides required for life could form under abiotic conditions?
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by Stanley Miller in 1953
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were carbon dioxide and oxygen included in miller's reaction chamber, which contained substances intended to duplicate the atmosphere of ancient earth?
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no
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clay crystals were thought to be the primitive template used for what?
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protein synthesis
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what is the basic unit of the nerbous system?
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the neuron
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which neurons have receptors for detection of stimull, relay information to the spinal cord, and are part of a reflex arc?
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sensory neurons
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state the sequence of the three types of neurons
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sensory neurons ---> interneurons ---> motor neurons
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what is the axon?
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the single long process that extends from a typical motor nerve
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what is the input zone of most neurons?
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usually the cell body or its dendrites, but not the axon or its terminals
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with a single neuron, what is the direction that an impulse follows?
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dendrite ---> cell body ---> axon
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what is a nerve impulse?
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a series of changes in membrane potentials
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what happens when a neuron is at rest?
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1. there is a voltage difference across the membrane of about 70 millivolts
2. the interior is negatively charged 3. it is not responding to a stimulus 4. the fluid outside the membrane has more sodium and less potassium than the cytoplasm |
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at rest, a nerve cell has a high concentration of what inside and a high concentration of what outside?
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potassium inside and sodium outside
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depolarization-repolarization describes what?
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what happens to a neuron as an impulse passes along it
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what is the term that most accurately describes the cellular activity associated with the actual passage of a nerve impulse?
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a wave of depolarization
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what is a chemical synapse?
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a junction between two neurons
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transmitter substance bridges the gap between what?
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a neuron sending a message and the neuron receiving it
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which kind of substances include acetylcholine, change the permiability of postsynaptic cells, may be excitatory or stimulatory, and may participate in synaptic integration?
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transmitter substances
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what is the definition of a "nerve"
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a bundle of axons
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what does the myelin sheath do?
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1. it is formed by the schwann cell
2. speeds up the transmission of impulses 3. does not surround all nerves 4. extends from node to node |
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what is the simplest nerve pathway?
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the reflex arc
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what is described as an adaptation that enables humans to stand upright, activated by stretch-sensitive receptors inside the muscle spindles, a simple, stereotyped, and repeatable motor action, and elicited by a sensory stimulus?
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the stretch reflex
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what are the two major divisions of the vertebral nervous system?
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the central and peripheral nervous systems
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what are the two princpal divisions of the peripheral nervous system?
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the somatic and autonomic systems
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the word hormone comes from the Greek word meaning what?
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set in motion
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target cells are equipped with what?
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specific receptor molecules and may occur in any part of the body
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what are pheromones primarily used for?
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arousing interest in a potential mate
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how are hormones distributed throughout the body?
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by the blood circulatory system
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what is the primary purpose of the endocrine system?
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to maintain a relatively constant internal environment
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the release of cyclic AMP as a second messenger is a response to what?
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peptide and glycoprotein hormones
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what is another name for the pituitary gland?
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the master gland
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what controls the pituitary gland?
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the hypothalamus
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give an example of an organ that is nervous in origin, structure, and function but secretes substances into the bloodstream
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the posterior pituitary
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what links the activities of the endocrine system and nervous system by neurohormones being secreted in response to the summation of neural messages that enter the hypothalamus?
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the hypothalamus and pituitary
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if you were cast upon a desert island with no water to drink, what in your bloodstream would rise in an effort to conserve water?
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antidiuretic hormone
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what hormone controls water balance, controls the concentration of urea in the urine, influences blood pressure, and changes the permeability of the urine-conducting tubules so that the interstitial fluid increases?
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the antidiuretic hormone
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where do the anterior pituitary secretions produce their effects?
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in the gonads, thyroid glands, adrenal glands, and mammary glands
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what is the most general (it may affect almost any cell in the body) pituitary hormone?
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somatotropin
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what does prolactin do?
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stimulates the mammary glands to produce milk
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what is the growth hormone?
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somatotropin
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what is the immediate stimulus for the release of milk from the female breast?
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the mechanical stimulation of the breast by sucking
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dwarfism may be due to reduced production of what?
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somatotropin
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what is the result of excessive secretion of somatotropin by adults?
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acromegaly
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what is the pineal gland associated with?
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biological clocks or biorhythms
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does asexual reproduction promote genetic variation in each successive generation?
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no
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what is the first stage in development?
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the zygote
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what happens to the zygote shortly after fertilization?
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successive cell divisions convert the zygote into a multicellular embryo during a process known as cleavage
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what is one of the last developmental events in tissue?
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specialization
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in humans, what events occur over the longest period of time?
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growth and tissue specialization
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in the human male how many sperm are produced by spermatogenesis and where does this occur?
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several hundred million sperm, occuring in the seminiferous tubules of the testes
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is sperm stored in the seminal vesicles ("sperm vessels")? if not, then where?
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no, they are stored in the epididymis
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are the mammary glands included in the femail reproductive system?
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no
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what is the primary reproductive organ in the human female?
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the ovary
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what is an oviduct and what is its function?
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its the passageway that channels ova from the ovary into the uterus
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is the cervix part of the uterus?
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yes
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is the clitoris essential to the reproductive process?
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no
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is an orgasm necessary for ejaculation of semen?
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yes
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where does fertilization in mammals occur?
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in the oviduct
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what is the average number of sperm that are deposited in the vagina during an ejaculation?
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between 150 and 350 million
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is the embryo recognizable as a human?
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yes
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what is the embryo called by the eighth week of pregnancy?
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a fetus
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what are prolactin and oxytocin?
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the female hormones that participate in milk production for the newborn
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