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81 Cards in this Set

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