Final Review Questions

Terrestrial animals tend to lose water to their environment through evaporation. In which of the following scenarios would a terrestrial animal begin to lose water through evaporation more quickly? a. An increase in the humidity of the animal's environment b. A decrease in the permeability of the animal's outer surface to water c. An increase in the metabolic rate of the animal d. A decrease in wind speed in the animal's environment

c. An increase in the metabolic rate of the animal

The falling phase of an action potential is generated primarily by a. the opening of voltage-gated Na+ channels b. the closing of voltage-gated Na+ channels c. The opening of voltage-gated K+ channels d. The closing of voltage-gated K+ channels

c. The opening of voltage-gated K+ channels

Latrotoxin and alpha-neurotoxin are two separate types of toxin that are similar in the following way : a. both toxins cause muscles to contract b. both toxins bind to acetylcholine receptors c. both toxins disrupt signaling between motor neurons and muscles d. all of these answers are correct

c. both toxins disrupt signaling between motor neurons and muscles

Pit vipers are able to "see" homeotherms using heat-sensitive pits in their face. These pits are sensitive to heat because they contain cells that express... a. heat-sensitive lipids b. heat-sensitive G protein-coupled receptors c. heat-sensitive TRP ion channels d. heat-sensitive aquaporins

c. heat-sensitive TRP ion channels

All else being equal, action potentials will take less time to travel down an axon if a. the neuron is receiving larger amount of excitatory input b. the diameter of the axon is smaller c. the axon is shorter d. the axon is not insulated with myelin

c. the axon is shorter

Elasmobranchs in seawater will tend to ____ from their environment a. gain water and lose ions b. lose water and gain ions c. lose water and ions d. gain water and ions

d. gain water and ions

How is the strength of sensory input encoded and communicated by sensory receptors? Please give separate answers for (a) how weak vs strong excitatory signals will be encoded by the dendrites of a sensory cells; (b) how weak vs strong input will be transmitted down the axon of the sensory cells; (c) how weak vs strong input will be communicated to a post-synaptic neuron by the pre-synaptic terminal of the sensory cell.

(a) stronger excitatory signals will be associated with greater local membrane depolarization of dendrites (b) Stronger signals will be associated with denser trains of action potentials moving down axons (c) Stronger signals will be associated with the release of more neurotransmitters by the pre-synaptic terminal

Rome and Lindstedt explain that the high-frequency muscles that toadfish use to produce sound consume ATP at a much higher rate than the low-frequency muscles that toadfish use to swim. Why is this?

ATP is spent to drive myosin's walking movement across actin, so more frequent muscle contractions will take more ATP ATP is spent to pump calcium ions back into the SR, so ore frequent muscle relaxations will take more ATP.

What are the three physiological factors that influence the binding affinity of hemoglobin for O2?

CO2 concentration, pH, and temperature

Humans use three cone photoreceptors for color vision. In comparison, mantis shrimp have as many as twelve different types of photoreceptors that are each sensitive to different wavelengths of light. This led to predictions that mantis shrimp are able to more finely distinguish between colors than we are, but it has turned out that we are better at distinguishing between colors than mantis shrimp. How is this so?

Humans are better at distinguishing colors than mantis shrimp because although the mantis shrimp have more photoreceptors and increased sensitivity to different wavelengths of light, they only process the color that is most detected by a photoreceptor rather than undergoing extensive color perception.

If an animal needs to be able to detect very low concentrations of a particular toxin in the food that it eats, would it be better off using ionotropic receptors or metabotropic receptors to detect the toxin? Why?

If an animal needs to be able to detect very low concentrations of a particular toxin in food, it would be better off using metabotropic receptors. Metabotropic receptors are a better choice because they better amplify a signal than ionotropic receptors. One metabotropic receptor can activate multiple G proteins kicking off signaling cascades that will amplify the signal.

If our blood contained the same amount of hemoglobin but we didn't package hemoglobin in red blood cells, what would happen to our blood? And how would this change the speed at which blood moves through our circulatory system?

If our blood contained the same amount of hemoglobin but we didn't package hemoglobin in red blood cells, the viscosity of our blood would increase. This would change the speed at which blood moves through our circulatory system by slowing the flow rate as more viscous fluid results in slower flow rates.

What would happen to the "vertebrate stretch reflex" if the inhibitory interneuron was removed and there were now direct excitatory connections between the sensory neuron and both motors neurons?

If there were direct excitatory connections between the sensory neuron and both motor neurons, both the flexor and the extensor muscle would contract

How do the circulatory system, the kidneys, and the nervous system respond to low blood pressure?

In response to low blood pressure, juxtaglomerular cells in the kidneys recognize the drop in blood pressure and secrete renin. Renin catalyzes the first step of the renin-angiotensin-aldosterone system. Angiotensin II, a product of the renin-angiotensin-aldosterone system, stimulates ADH secretion from neurosecretory cells in the hypothalamus and promotes thirst increasing extracellular fluid volume. Angiotensin II also stimulates the circulatory system to constrict systemic arterioles. The renin-angiotensin-aldosterone system also causes aldosterone secretion from the adrenal cortex causing an increase in sodium reabsorption subsequently increasing the extracellular fluid volume and increasing arterial blood pressure.

How do the kidneys, the digestive system, and the skeletal system respond to low concentrations of calcium in the blood?

In response to low concentrations of calcium in the blood, PTH stimulates cells in the nephron to reabsorb Ca2+ for increased calcium retention. PTH also stimulates some of the cells in the nephron to convert inactive vitamin D to an active form. The active vitamin D promotes Ca2+ absorption in the intestine. Active vitamin D also interacts with PTH to cause bond resorption. Bone resorption releases Ca2+ into the extracellular fluid

Why do large, active animals need respiratory pigments in order to survive?

Large, active animals need respiratory pigments in order to survive because their oxygen demands cannot be met by blood's oxygen-carrying capacity alone. In humans, respiratory pigments increase the blood's oxygen-carrying capacity by about 50x to compensate for our high oxygen demands.

With only four tympanal organs, moths can learn a number of things about the locations of the echolocating bats that prey on them. Please explain how moths make comparisons between their tympanal organs to (a) assess the direction of an echolocating bat and (b) assess the proximity of an echolocating bat.

Moths assess the direction of an echoloating bat by having two tympanal organs on each side of the thorax allowing for the moth to discern whether the bat is approaching from the left or the right. Moths assess the proximity of an echolocating bat by having both high sensitivity and low sensitivity tympanal organs. High sensitivity tympanal organs allow the moth to know that the bat is in the general area. Low sensitivity tympanal organs allow the moth to know that the bat is in close proximity and generates an action potential.

Rome and Lindstedt state that "cellular structures are competing for space in muscle fibers". What are the three types of structures that are competing for space and what are the functional contributions of each structure to muscle performance?

Myofibrils provide the basic structure of muscles SR is integral in turning muscle on and off as Ca2+ is pumped into the SR to determine the max frequency the muscle can operate at. Mitochondria is the site of aerobic metabolism required to generate ATP to sustain muscle activity.

How do respiratory pigments lower the partial pressure of O2 in the blood while increasing the concentration of O2 in the blood?

Respiratory pigments lower the partial pressure of O2 in the blood while increasing the concentration of O2 in the blood because oxygen bound to respiratory pigments does not contribute to the partial pressure of oxygen in the blood. Only free molecules of oxygen contribute to the partial pressure of oxygen in the blood. However, oxygen bound to respiratory pigments still contribute to the concentration of O2 in the blood.

Please explain three ways that squid compensate for challenges surrounding their ability to deliver oxygen to their tissues.

Squid's body composition is favorable for cutaneous oxygen uptake and squids arrange the majority of their mitochondria-rich fibers along the internal and external surfaces of the mantle. This allows the mitochondria-rich fibers to be in close contact with the seawater maximizing the oxygen partial pressure gradient across the skin into the muscles thus increasing oxygen acquisition. Some species of squid undergo metabolic suppression at depth during the day to reduce oxygen consumption. These ocean depths are characteristically cold increasing the affinity of hemocyanin for oxygen and allowing for sufficient oxygen procurement to meet resting metabolic demands. Lastly, during metabolic suppression squids generate ATP through anaerobic respiration using octopine dehydrogenase to convert pyruvic acid and arginine to octopine which generates more NAD to continue anaerobic glycolysis.

What is a challenge, related to oxygen supply that squid face from their own physiology?

Squids use hemocyanin as a respiratory pigment but due to the viscosity constraints of hemocyanin, the respiratory pigment is present in low concentrations. Therefore, squids' oxygen-carrying capacity is low causing the organism to exhaust all of its blood-borne oxygen for each circulatory cycle. This results in a loss of venous oxygen reserves.

What is a challenge, related to oxygen supply, that squid face from their external environment?

That their environment is characteristically deoxygenated making it difficult to meet the high oxygen demands resulting from their high metabolic rate.

Neurons often receive input from many other neurons. Sometimes neurons receive excitatory and inhibitory input at the same time. How do neurons integrate this information to "decide" whether or not to generate action potentials?

When both excitatory and inhibitory input are received at the same time, it will cause localized depolarization and hyperpolarization but not at the axon initial segment. The depolarizing charge, greater than the voltage threshold, must accumulate at the axon initial segment in order to generate an action potential. Therefore, a received excitatory or inhibitory input does not directly contribute to the potential action of the neuron unless it travels/accumulates at the axon initial segment.

How does liver function relate to the following? a. the digestive system b. the circulatory system c. the endocrine system d. the kidneys e. skeletal muscle

a. Liver function relates to the digestive system as one of the liver's main functions is macronutrient metabolism and the breakdown of xenobiotic compounds b. Liver function relates to the circulatory system as one of the liver's main functions is blood volume regulation c. Liver function relates to the endocrine system as one of the liver's main functions is endocrine control of growth signaling pathways d. Liver function relates to the kidneys as one of the liver's main functions is to facilitate the disposal of nitrogenous waste in the form of urea metabolism Liver function relates to the skeletal muscle as their roles in glucose and amino acid metabolism are interconnected

Which of the following types of taste receptor cells do not employ metabotropic sensory transduction? a. Salt receptors b. Umami receptors c. Sweet receptors d. Bitter receptors

a. Salt receptors

If you discovered a new type of statocyst, what type of receptor proteins would you most expect to find in its receptor cells? a. Stretch-activated ion channels b. Temperature-sensitive ion channels c. GPCRs d. Ligand-gated ion channels

a. Stretch-activated ion channels

Changes in membrane potential cause voltage-gated Na+ and K+ channels to a. change in shape b. release neurotransmitters c. be added or subtracted from cell membranes d. change in charge

a. change in shape

The action potentials of spiking neurons can be described as having four phases: a resting phase, a rising phase, a falling phase, and a recovery phase, What is the state of the voltage-gated Na+ channels during each of these four phases? a. closed, open, inactivated, closed b. closed, open, closed, open c. open, closed, inactivated, open d. open, inactivated, closed, open

a. closed, open, inactivated, closed

An important difference between terrestrial animals that can survive in dry environments and those that cannot survive in these environments is the ability to _____? a. dilute blood plasma by producing hyper-osmotic urine b. concentrate blood plasma by producing hypo-osmotic urine c. produce H2O through aerobic metabolism d. produce H2O through anaerobic metabolism

a. dilute blood plasma by producing hyper-osmotic urine

Consider a myelinated neuron from a vertebrate and a non-myelinated neuron from an invertebrate. Both of these neurons generate and transmit action potentials. Their axons have the same lengths and diameters. Compares to the invertebrate neuron, you would expect the vertebrate neuron to have a. fewer voltage-gated Na+ channels b. More voltage-gated K+ channels c. Action potentials with lower peak amplitudes d. Action potentials with higher peak amplitudes

a. fewer voltage-gated Na+ channels

Which of the following types of molecules carry information from pre-synaptic neurons to post-synaptic neurons at electrical synapses? a. ions b. neurotransmitters c. hormones d. electrons

a. ions

Which of the following is not controlled by the autonomic nervous system in vertebrates? a. skeletal muscle b. the pacemaker region of the heart c. smooth muscle in the digestive organs d. sweat glands and tear glands

a. skeletal muscle

Which of the following types of hormones are usually received by intracellular receptors? a. steroid hormones b. peptide hormones c. amine hormones d. all of the above

a. steroid hormones

The rising phase of an action potential is generated primarily by the activity of a. voltage-gated Na+ channels b. voltage-gates K+ channels c. K+ leak channels d. Na+/K+ ATPase pumps

a. voltage-gated Na+ channels

The voltage threshold for a neuron represents the membrane potential at which a. voltage-gated Na+ channels open b. K+ leak channels open c. Voltage-gated Na+ channels close d. K+ leak channels open

a. voltage-gated Na+ channels open

If you were a doctor and had a patient with dangerously low blood pressure, which of the following drugs would you be most likely to give them? a. A drug that increases the filtration rate of nephrons b. A drug that increased levels of ADH c. A drug that increased metabolic rate d. A drug that caused blood vessels to vasodilate

b. A drug that increased levels of ADH

Sensory cells are used to detect changes in both the external and internal environments. What sorts of ion channels do you predict to be associated with the receptors that monitor blood pressure in vertebrates? a. Voltage-gated ion channels b. Stretch-gated ion channels c. Phosphorylation-gated ion channels d. Ligand-gated ion channels

b. Stretch-gated ion channels

Myelin sheaths increase the conduction velocity of action potentials by a. acting as electrical conductors for axons b. acting as electrical insulators for axons c. supplying additional voltage-gated ion channels to axons d. all of the above

b. acting as electrical insulators for axons

In the nephron of a mammal that is producing concentrated urine, fluid that is moving down the collecting duct encounters interstitial fluid in the medulla that has ______ a. decreasing levels of osmotic pressure b. increasing levels of osmotic pressure c. a constant osmotic pressure d. increasing or decreasing osmotic pressure depending on the species of mammal

b. increasing levels of osmotic pressure

Muscarine poisoning causes excessive sweating, constriction of the airways, slowed heart rate, stomach cramps, diarrhea, and lots of other unpleasant things. It does so by _____ the amount of signaling by the ______ nervous system. a. decreasing/parasympathetic b. increasing/parasympathetic c. decreasing/sympathetic d. increasing/sympathetic

b. increasing/parasympathetic

Which of the following types of molecules carry information from pre-synaptic neurons to post-synaptic neurons at chemical synapses? a. electrons b. neurotransmitters c. ions d. hormones

b. neurotransmitters

Juxtaglomerular cells release _____ when blood pressure is ____ a. ADH, low b. renin, low c. ADH, high d. renin, high

b. renin, low

Which part of the neuron is most directly associated with receiving neurotransmitters and responding to them? a. the pre-synaptic terminals b. the dendrites c. the cell body d. the axon

b. the dendrites

Which of the following represents the first step in neuron to neuron communication across a chemical synapse in which the post-synaptic cell has ionotropic receptors? a. the release of neurotransmitters by the pre-synaptic cell b. the opening of voltage-gated Ca2+ channels in the pre-synaptic terminal c. the opening of voltage-gated Na+ channels in the post-synaptic cell d. The closing of voltage-gated Na+ channels in the post-synaptic cell

b. the opening of voltage-gated Ca2+ channels in the pre-synaptic terminal

Which part of a neuron is most directly associated with the release of neurotransmitters? a. the cell body b. the pre-synaptic terminals c. the dendrites d. the axon

b. the pre-synaptic terminals

In which part of a nephron do transporters actively move NaCl from the fluid inside the nephron to the interstitial fluid surrounding the nephron? a. Descending limb of the loop of Henle b. Bowman's capsule c. Ascending limb of the loop of Henle d. Collecting duct

c. Ascending limb of the loop of Henle

A cell in the body of an animal has an osmotic pressure of 300 mOsm. If the osmolarity of the surrounding fluid increases, what could the cell do to maintain a constant volume without changing the electrical gradient across its cell membrane? a. It could increase its internal concentration of negatively charged molecules b. It could increase its internal concentration of positively charged molecules c. It could increase its internal concentration of non-charged molecules d. It could decrease its internal concentration of non-charged molecules

c. It could increase its internal concentration of non-charged molecules

Take a close look at Figure 20.7 from the textbook. From lecture, you know that the DHPR protein is voltage sensitive. If this protein stopped changing shape in response to action potentials, what would it mean for muscle contractions? a. Muscles would not be able to relax b. Muscles would fatigue more rapidly c. Muscles would not be able to contract d. Action potentials would stop traveling along muscle fibers

c. Muscles would not be able to contract

Which of the following events occur when muscle fibers contract? a. the lengths of the thick (myosin) filaments decrease b. the lengths of the thin (actin) filaments decrease c. The amount of overlap between the thick (myosin) filaments and the thin (actin) filaments increase d. all of the answers are correct

c. The amount of overlap between the thick (myosin) filaments and the thin (actin) filaments increase

To achieve finer motor control, you'd expect to see muscles with.... a. few separate fibers all controlled by a single motor neuron b. many separate fibers all controlled by a single motor neuron c. many separate fibers controlled by many separate motor neurons d. few separate fibers controlled by many separate motor neurons

c. many separate fibers controlled by many separate motor neurons

If you had a muscle cell with a relatively low number of Ca2+ ATPase pumps in its sarcoplasmic reticulum, you would expect that the muscle fiber would a. contract more slowly than other similar muscle fiber b. relax more quickly than the other similar muscle fibers c. relax more slowly than other similar muscle fibers d. contract more quickly than other similar muscle fibers

c. relax more slowly than other similar muscle fibers

If the gills of a freshwater fish suddenly become less permeable to water a. The fish would start producing urine that is more dilute b. the fish would have an easier time obtaining oxygen from water c. the fish would have a more difficult time obtaining oxygen from water d. the fish would start producing greater volumes of urine

c. the fish would have a more difficult time obtaining oxygen from water

Echinoderms like sea urchins and sea stars differ from vertebrates in which of the following ways? a. they don't have neurons b. they don't have synapses c. they don't have a single, central brain d. they don't have sensory neurons

c. they don't have a single, central brain

In which part of a nephron does a change in permeability to water determine whether dilute urine or concentrated urine is produced? a. Descending limb of the loop of Henle b. Bowman's capsule c. Ascending limb of the loop of Henle d. Collecting duct

d. Collecting duct

Action potential tend to travel in a single direction down an axon because of a. temporarily inactivated K+ channels b. Permanently open Na+ channels c. Glial cells d. Temporarily inactive Na+ channels

d. Temporarily inactive Na+ channels

If a mussel (an osmotic conformer) has body fluids with an osmolarity of 500 mOsm, what will happen if it is placed in seawater? a. The osmolarity of its body fluids will decrease to 250 mOsm b. The osmolarity of its body fluids will increase to 750 mOsm c. The osmolarity of its body fluids will remain at 500 mOsm d. The osmolarity of its body fluids will increase to 1000 mOsm

d. The osmolarity of its body fluids will increase to 1000 mOsm

Following Figure 14.16, what would happen to a person's sense of taste if they lost the ability to produce T1R3 proteins? a. They would lose their ability to detect sweet-tasting molecules b. They would lose their ability to detect umami flavors c. They would lose their ability to detect bitter flavors d. They would lose their ability to detect sweet-tasting molecules and umami flavors

d. They would lose their ability to detect sweet-tasting molecules and umami flavors

A functional circulatory system is necessary for the long-range transmission of which of the following types of hormones? a. steroid hormones b. peptide hormones c. amine hormones d. all of the above

d. all of the above

Antidiuretic hormone upregulates the ____ of aquaporins into the apical membrane of the collecting duct so that more water can be ______ a. removal, reabsorbed b. removal, excreted c. insertion, excreted d. insertion, reabsorbed

d. insertion, reabsorbed

In neurons that generate action potentials, the strengths of signals may be reflected by a. the speeds at which action potentials travel b. the directions in which the action potentials travel c. the amplitudes of the action potentials generated d. the numbers of action potentials generated

d. the numbers of action potentials generated

How do elasmobranchs manage to be both hyperosmotic and hypoionic to seawater? a. they maintain very high concentrations of Na+ dissolved in their body fluids b. they maintain high concentrations of ammonia dissolved in their body fluids c. they maintain low concentrations of K+ dissolved in their body fluids d. they maintain high concentrations of urea dissolved in their body fluids

d. they maintain high concentrations of urea dissolved in their body fluids

Brains have somatotopic maps: parts of the body are mapped onto the cerebral cortex in ways that preserve their anatomical positions on the body. The hands and feet of humans are roughly the same in size, but hands and fingers are associated with much larger portions of the somatosensory cortex and the primary motor cortex than the feet and toes. Why might this be so?

somatosensory cortex: A greater density of sensory receptors on the hands than on the feet leads to hands taking up a greater amount of available space on the somatosensory cortex. Greater sensor density leads to finer spatial perception by the hands than the feet. Primary motor cortex: A greater density of motor neurons travel from the brain to the hands than from the brain to the feet, leading to more of the motor cortex needing to be dedicated to motor neurons associated with the hands. More numerous motor neurons leads to us having finer motor control over our hands than our feet.