BIO 1520 Module 3
The steps below refer to various stages in transmission at a chemical synapse: 1. Neurotransmitter binds with receptors associated with the postsynaptic membrane. 2. Calcium ions rush into neuron's cytoplasm. 3. An action potential depolarizes the membrane of the axon terminal. 4. The ligand-gated ion channels open. 5. The synaptic vesicles release neurotransmitter into the synaptic cleft. Which sequence of events is correct?
3 2 5 1 4
Which one of the following statements is correct? Local regulators are signals that link neighboring cells. The series of changes in cellular proteins that convert the extracellular signal to a specific intracellular response is called signal transduction. Receptors for steroid hormones are located inside target cells. Many hormones elicit more than one type of response in the body. All of the above statements are true.
All of the above statements are true.
The action of a local regulator is illustrated when _____. there is relaxation of arterial smooth muscle caused by nitric oxide prostaglandins released from the placenta alter the excitability of the muscle of the uterus growth factor stimulates the growth of embryonic cells cytokines play a role in immune responses All of the choices are correct
All of the choices are correct
Why might animal hormones function differently from plant hormones?
Animals move rapidly away from negative stimuli, and most plants don't, and plants are much more variable in their morphology and development than animals
What would happen if the secondary messenger cGMP was blocked in the de-etiolation pathway?
Ca2+ channels could open, and specific protein kinase 2 could still be produced
Which one of the following statements about hormones or the endocrine system is correct? Hormones are distributed only to specific cells having the appropriate membrane receptors. Hormones result in quick, short responses, compared with nervous system responses. Hormones are secreted onto a surface of the body. Endocrine organs are sometimes derived from nervous tissue. None of the choices is correct.
Endocrine organs are sometimes derived from nervous tissue
Which of the following is a common feature of all hormones? Hormones levels are controlled by the pituitary gland. Hormones act as a chemical signal between cells. Hormones are produced in response to stress. Hormones are proteins. Hormones enter a cell, bind to their receptor, and interact with DNA
Hormones act as a chemical signal between cells
The general functions of the nervous system include which of the following? I integration II motor output III sensory input
I, II and III
Which one of the following statements about the endocrine functions of the pancreas is correct? Beta cells make glucagon. Diabetes mellitus is caused by a deficiency of glucagon. Insulin triggers the uptake of glucose from the blood. Alpha cells make insulin. None of the choices is correct.
Insulin triggers the uptake of glucose from the blood.
A response requires...
Signal, reception, transduction
Which statement about the lobes of the pituitary is correct? The anterior pituitary receives hypothalamic hormones from brain cells. The hypothalamus sends hormones to the anterior pituitary. The posterior lobe of the pituitary is glandular tissue closely associated with the brain. The posterior pituitary produces oxytocin and antidiuretic hormone. The anterior lobe of the pituitary is nervous tissue that connects directly to the brain.
The hypothalamus sends hormones to the anterior pituitary
Plants growing in a partially dark environment will grow towards light in a response called phototropism. Choose the incorrect statement regarding phototropism. a) auxin causes a decrease in growth on the side of the stem exposed to light b) removing the apical meristem prevents phototropism c) one chemical involved in auxin d) it is caused by a chemical signal e) auxin causes a growth increase on one side of the stem
a
Skeletal fibers may be classified as either oxidative or glycolytic. Which of the following muscles would be called oxidative? a) the ones most resistant to fatigue b) those with very few mitochondria c) the white muscle meat of poultry d) those with a very low concentration of myoglobin e) those with the largest muscle fiber diameters
a
The endocrine system and the nervous system are structurally related. Which best illustrates this relationship? a) a neurosecretory cell in the hypothalamus b) a neuron in the spinal cord c) a cell in the pancreas that produces digestive enzymes d) a brain cell in the cerebral cortex e) a steroid-producing cell in the adrenal cortex
a
Which is an example of a peptide hormone? a) insulin b) testosterone c) cortisol d) androgen e) estrogen
a
Neurons consist of _____.
a cell body, dendrites, and an axon
The observation that the acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of
a ligand-gated sodium channel
The hormone that helps plants respond to drought is
abscisic acid
Auxin enhances cell elongation in all of these ways except gene activation. cell wall loosening. increased uptake of solutes. acidification of the cell wall, causing denaturation of growth-inhibiting cell wall proteins. increased activity of plasma membrane proton pumps.
acidification of the cell wall, causing denaturation of growth-inhibiting cell wall proteins
Neurotransmitters affect postsynaptic cells by causing molecular changes in the cells. altering the permeability of the cells. initiating signal transduction pathways in the cells. affecting ion-channel proteins. all of the above
all of the above
Plant hormones produce their effects by
altering the expression of genes, and modifying the permeability of the plasma membrane
The apical bud of a pine tree inhibits the growth of lateral buds through the production of
auxin
Which of the following statements about plant hormones is false? a) cytokinins promote cell division b) abscisic acid generally promotes growth c) gibberellins stimulate cell enlargement d) ethylene contributes to the aging of plants e) the growth of plants in nature is probably regulated by a combination of growth-stimulating and growth-inhibiting hormones
b
Polypeptide hormones
bind to surface receptors on target cells
If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering? a) 4 hours light/20 hours dark b) 8 light/16 dark c) 8 light/8 dark/light flash/8 dark d) 2 light/20 dark/2 light e) 6 light/2 dark/light flash/16 dark
c
A stimulus can trigger an action potential by _____.
causing sodium ions to enter the neuron
Most of the organelles in a neuron are located in the
cell body
External stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the
cell membrane
Complex fire/don't fire "decision making" by neurons is most directly a result of _____
combination of signals from excitatory and inhibitory synapses
Buds and sprouts often form on tree stumps. Which of the following hormones would you expect to stimulate their formation?
cytokinins
Which hormone is incorrectly paired with its function? ethylene - inhibits cell elongation abscisic acid - promotes seed dormancy cytokinins - initiate programmed cell death auxin - promotes stem growth through cell elongation gibberellins - stimulate seed germination
cytokinins - initiate programmed cell death
A motor unit includes a) a motor neuron in the spinal cord b) multiple muscle fibers in one muscle c) multiple muscles within a single muscle complex d) a and b e) a, b, and c
d
A pre-synaptic autonomic fiber secretes Ach, whereas the post-synaptic fiber secretes nor-epinephrine. These two fibers are a) part of the sympathetic nervous system b) included in lumbar and thoracic spinal nerves c) included in cranial nerves or sacral spinal nerves d) a and b e) a, b, and c
d
Hair cells are associated with a) hearing b) vestivular system c) circulating the endolymph in semi-circular canals d) a and b e) a, b, and c
d
What is the role of calcium in muscle contractions? a) activate to the ATPase enzyme in myosin b) bind to troponin, thus exposing myosin binding sites on actin c) form cross-bridges during muscle shortening d) a and b e) a, b and c
d
Which hormone exerts antagonistic action to insulin? a) calcitonin b) growth hormone c) epinephrine d) glucagon e) thyroxine
d
Which of the following conditions would prevent a molting larval insect from transforming into an adult? a) decreased level of ecdysone b) lack of juvenile hormone c) lack of the melatonin hormone d) increased level of juvenile hormone e) lack of ecydsone
d
Animals skeletons provide a) protection b) support c) articulation d) a & b e) a, b & c
e
Glial cells in the nervous system are responsible for a) insulating axons and preventing "crosstalk" between adjacent fibers b) supporting and nuturing neurons and axons c) facilitating the normal function and development of new synapses d) a and b e) a, b, and c
e
Plant phytochromes a) respond to specific wavelengths of light b) are involved in regulating life history responses of plants c) can influence responses throughout the plant body d) a and b e) a, b, and c
e
The secretion of hormone A causes a change in the amount of protein X in an organism. If this mechanism works by negative feedback, which of the following would you expect to observe? a) an increase in A produces an increase in X b) a decrease in A produces an increase in X c) an increase in X produces a decrease in A d) a and b e) b and c
e
The ripening of fruit and the dropping of leaves and fruit are principally controlled by
ethylene
A "resting" motor neuron is expected to
exhibit a resting potential that is more negative than the "threshold" potential.
Neurotransmitters are released from axon terminals via
exocytosis
True or false: every cell in the body responds to every chemical sign
false
True or false: in animals, the contractile protein actin is found only in muscle cells
false
True or false: the brain can discriminate amongst sensory inputs by the qualities of individual action potentials
false
True or false: the ratio of pre-synaptic to post-synaptic fibers is always 1:1
false
A prolonged muscle contraction due to a lack of relaxation between successive stimuli will ultimately result in
fatigue
Which function below is not influenced by thyroid hormones? muscle tone blood pressure maintenance growth rate rate of cellular respiration fight-or-flight response
fight-or-flight response
The synthesis of which of the following hormones would be a logical first choice in an attempt to produce normal growth in mutant dwarf plants?
gibberellin
Which one of the following reflects an increase in the magnitude of the membrane potential?
hyperpolarization
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
hyperpolarization of the neuron
Perception and discrimination of sensory modalities (eg hearing, taste, smell, etc) occurs
in specialized regions of the cerebrum
According to the acid growth hypothesis, auxin works by
increasing wall plasticity and allowing the affected cell walls to elongate
Most of the neurons in the human brain are
interneurons
Myoglobin
is found in muscles and binds oxygen and is an adaptation to improve muscle resistance to fatigue
In their mechanism of action, a difference between lipid-soluble and water-soluble hormones is that _____
lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA
Lack of rhodopsin in human photoreceptors would cause
loss of night vision
What directly coordinates many autonomic functions?
medulla oblongata
Action potentials move along axons
more rapidly in myelinated than in non-myelinated axons
The fundamental cell type in a nervous system is a(n) _____
neuron
The speed of action potential is greatly increased by the formation of _____ by _____ cells in the CNS and _____ cells in the PNS
nodes of Ranvier.....oligodendrocytes.....Schwann cells
All of the following may function in signal transduction in plants except phytochrome. receptor proteins. calcium ions. second messengers. nonrandom mutations
nonrandom mutations
What portion of the brain has neurons that receive action potentials from photoreceptor cells in the eye?
occipital lobe
Routine homeostasis of internal conditions is the primary responsibility of which portion of the vertebrate nervous system?
parasympathetic
If protein synthesis was blocked in etiolated cells, what would be necessary for the "greening" of these cells?
post-translational modification of existing proteins
The surface on a neuron that discharges synaptic vesicles is the
presynaptic membrane
A nerve poison that blocked acetylcholine receptors on dendrites would _____
prevent the binding of a signal that crossed the synaptic gap
Which of the following is not a typical component of a signal transduction pathway? - production of second messengers such as cGMP - activation of protein kinases - expression of specific proteins - production of more signal - phosphorylation of transcription factors
production of more signal
Which of the following is an exocrine gland? pituitary gland adrenal gland islets of Langerhans salivary gland None of the choices is an exocrine gland
salivary gland
The operation of the sodium-potassium "pump" moves
sodium ions out of the cell and potassium ions into the cell
The adrenal cortex is responsible for secreting
steroid hormones
When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of
temporal summation
Release of tropic hormones from the anterior pituitary is directly the result of factors secreted by
the brain, the hypothalamus
In humans, paralysis of muscles attached to the appendicular skeleton would cause
the inability to move
The critical factor(s) determining flowering responses in many plants is(are)
the length of night
After the depolarization phase of an action potential, the resting potential is restored by
the opening of voltage-gated potassium channels and the closing of sodium activation gates
In the sequence of permeability changes for a complete action potential, the first of these events that occurs is
the opening of voltage-gated sodium channels
Which of the following best describes a nerve signal?
the sequential depolarization of the membrane of a neuron
Which of the following is crucial to maintaining the resting potential (the difference in the electrical charge inside and outside a neuron membrane that enables the cell to transmit a signal)?
the transport of sodium and potassium ions by the sodium/potassium pump
True or false: dogs have an extra sense of smell, the vomeronasal organ, that is lacking in humans
true
True or false: exposure to a far-red light will convert phytochromes from the active to inactive state
true
True or false: in animals, taste buds can be found in parts of the body other than the tongue
true
True or false: smooth muscle has actin and myosin but lacks sarcomeres
true
True or false: specific regions of the cerebrum are dedicated to interpreting and controlling the highly specific cognitive functions, hence damage to a specific region can lead to unrecoverable loss of that specific function
true
True or false: the simplest reflex arc includes only three elements: receptor, sensory neuron, and motor neuron
true