Organisms maintain dynamic homeostasis through behavioral and physiological mechanisms. Which of the following statements is an accurate explanation of a negative feedback mechanism used by animals to regulate body temperature?
A) Squirrels are able to cool themselves during warmer months by producing more brown fat, which contains abundant mitochondria and a rich blood supply.
B) Desert jackrabbits have unusually large ears that serve as solar heat collectors to enable them to maintain their body temperatures.
C) A ground squirrel's hypothalamus detects changes in environmental temperatures and responds by activating or suppressing metabolic heat production.
D) A goldfish slows its movements when the water temperature is lower.
The body tissue that consists largely of material located outside of cells is
A) epithelial tissue.
B) connective tissue.
C) muscle tissue.
D) nervous tissue.
Which of the following would increase the rate of heat exchange between an animal and its environment?
A) feathers or fur
B) vasoconstriction
C) wind blowing across the body surface
D) countercurrent heat exchanger
Consider the energy budgets for a human, an elephant, a penguin, a mouse, and a snake. The ________ would have the highest total annual energy expenditure, and the ________ would have the highest energy expenditure per unit mass.
A) elephant; mouse
B) elephant; human
C) mouse; snake
D) penguin; mouse
Compared with a smaller cell, a larger cell of the same shape has
A) less surface area.
B) less surface area per unit of volume.
C) the same surface-area-to-volume ratio.
D) a smaller cytoplasm-to-nucleus ratio.
An animal's inputs of energy and materials would exceed its outputs
A) if the animal is an endotherm, which must always take in more energy because of its high metabolic rate.
B) if it is actively foraging for food.
C) if it is growing and increasing its mass.
D) never; due to homeostasis, these energy and material budgets always balance.
You are studying a large tropical reptile that has a high and relatively stable body temperature. How do you determine whether this animal is an endotherm or an ectotherm?
A) You know from its high and stable body temperature that it must be an endotherm.
B) You subject this reptile to various temperatures in the lab and find that its body temperature and metabolic rate change with the ambient temperature. You conclude that it is an ectotherm.
C) You note that its environment has a high and stable temperature. Because its body temperature matches the environmental temperature, you conclude that it is an ectotherm.
D) You measure the metabolic rate of the reptile, and because it is higher than that of a related species that lives in temperate forests, you conclude that this reptile is an endotherm and its relative is an ectotherm.
Which of the following animals uses the largest percentage of its energy budget for homeostatic regulation?
A) marine jelly (an invertebrate)
B) snake in a temperate forest
C) desert insect
D) desert bird
Given that early land plants most likely share a common ancestor with green algae, the earliest land plants were most likely ________.
A) nonvascular plants that grew leafless, photosynthetic shoots
B) species that did not exhibit alternation of generations
C) vascular plants with well-defined root systems
D) plants with well-developed leaves
A fellow student brought in a leaf to be examined. The leaf was dark green, thin, had stoma on the lower surface only, and had a total surface area of ten square meters. Where is the most likely environment where this leaf was growing?
A) a large, still pond
B) a tropical rain forest
C) an oasis within a grassland
D) the floor of a deciduous forest
Phloem sap can flow ________.
A) from leaves to shoots only
B) from shoots to leaves only
C) from sites of sugar production to storage units only
D) both ways between production and storage sites
Why do most angiosperms have alternate phyllotaxy, with leaf emergence at an angle of 137.5° compared to leaves above and below?
A) to allow maximum exposure to light
B) to promote a leaf area index above 8
C) to reduce shading of lower leaves
D) to allow maximum exposure to light and to reduce shading of lower leaves
A plant developed a mineral deficiency after being treated with a fungicide. What is the most probable cause of the deficiency?
A) Mineral receptor proteins in the plant membrane were not functioning.
B) Mycorrhizal fungi were killed.
C) Active transport of minerals was inhibited.
D) The genes for the synthesis of transport proteins were destroyed.
Which one of the following does not correctly match the form with its function?
A) stem—water and minerals are transported upward
B) xylem sap—transport water and nutrients from roots to shoots upward
C) transpiration—loss of water mostly through stomata
D) cork cambium—increase in stem thickness
The leaf area index is the ratio of the ________.
A) upper leaf surface of a single plant divided by the surface area of the land on which the plant grows
B) lower leaf surface of a single plant divided by the surface area of the land on which the plant grows
C) upper leaf surface of a single plant multiplied by the surface area of the land on which the plant grows
D) lower leaf surface of a single plant multiplied by the surface area of the land on which the plant grows
Which one of the following played a critical role in the successful colonization of land by plants?
A) ground tissue
B) bacterial association
C) mycorrhizae
D) cuticle on leaf surface
Which structure or compartment is separate from the apoplastic route?
A) the lumen of a xylem vessel
B) the lumen of a sieve tube
C) the cell wall of a mesophyll cell
D) the cell wall of a root hair
The apoplast in plant tissues consists of ________.
A) cell walls, extracellular spaces, and plasmodesmata
B) cell walls, extracellular spaces, and vessel elements
C) vessel elements, plasmodesmata, and extracellular spaces
D) cell walls, plasma membrane, and cytosol
Active transport of amino acids in plants at the cellular level requires ________.
A) NADP and channel proteins
B) xylem membranes and channel proteins
C) sodium/potassium pumps and xylem membranes
D) ATP, transport proteins, and a proton gradient
The physical property that predicts the direction of water flow is referred as ________.
A) potassium pump
B) water potential
C) osmotic potential
D) sodium pump
What is the function of proton pumps localized in the plant plasma membrane?
A) to transfer phosphorus groups from ATP to proteins
B) to transfer metal ions across the plasma membrane
C) to transfer anions across the plasma membrane
D) to create a membrane potential
Which of following ions play the primary role in basic transport processes in plant cells?
A) H+
B) Na+
C) K+
D) Ca+2
Which of the following would be least likely to affect osmosis in plants?
A) a difference in solute concentrations
B) receptor proteins in the membrane
C) aquaporins
D) a difference in water potential
The movement of water across biological membranes can best be predicted by ________.
A) prevailing weather conditions
B) aquaporins
C) level of active transport
D) water potentials
If isolated plant cells with a water potential averaging -0.5 MPa are placed into a solution with a water potential of -0.3 MPa, which of the following would be the most likely outcome?
A) The pressure potential of the cells would increase.
B) Water would move out of the cells.
C) The cell walls would rupture, killing the cells.
D) Solutes would move out of the cells.
Solute potential in a cell is also called ________.
A) water potential
B) osmotic potential
C) potential gradient
D) pressure potential
The value for Ψ in root tissue was found to be -0.15 MPa. If you take the root tissue and place it in a 0.1 M solution of sucrose (Ψ = -0.23 MPa), the net water flow would ________.
A) be from the tissue into the sucrose solution
B) be from the sucrose solution into the tissue
C) be in both directions, and the concentration of water would remain equal
D) be impossible to determine from the values given here
In the transmembrane route for transport within plant tissue, ________.
A) water and solutes move out of one cell, across the cell wall, and into the neighboring cell
B) water and solutes move out of one cell, through the plasmodesmata, and into the neighboring cell
C) water moves out of one cell, across the cell wall, and into the neighboring cell
D) solutes move out of one cell, across the plasmodesmata, and into the neighboring cell
When an animal cell is placed in a hypotonic solution and water enters the cell via osmosis, the volume of the cell increases until it bursts. This does not happen to plant cells, because ________.
A) they have large central vacuoles, which provide abundant space for storage of incoming water
B) they have cell walls, which prevent the entry of water by osmosis
C) they have cell walls, which provide pressure to counteract the pressure of the incoming water
D) certain gated channel proteins embedded in their plasma membranes open as osmotic pressure decreases, allowing excess water to leave the cell
How does a flaccid cell differ from a turgid cell?
A) A flaccid cell has higher pressure potential.
B) A flaccid cell has lower pressure potential.
C) A flaccid cell has higher solute potential.
D) A flaccid cell has lower solute potential.
The protoplast consists of ________.
A) all cell components without a nucleus
B) all cell components without a cell membrane
C) only the cytoplasm and nucleus
D) the living part of the cell, including the cell membrane
Compared to a cell with few aquaporins in its membrane, a cell containing many aquaporins will ________.
A) have a faster rate of osmosis
B) have a lower water potential
C) have a higher water potential
D) have a faster rate of active transport
If you place flaccid plant cells in pure water, water ________ into cell because it has ________.
A) does not enter the cell; solutes and low water potential
B) enter the cell; solutes and low water potential
C) enter the cell; solutes and high water potential
D) does not enter the cell; solutes and high water potential
If ΨP = 0.3 MPa and ΨS = -0.45 MPa, the resulting Ψ is ________.
A) +0.75 MPa
B) -0.75 MPa
C) -0.15 MPa
D) +0.15 MPa
Which of the following are important components of the long-distance transport process in plants?
I) the cohesion of water molecules II) a negative water potential III) the root parenchyma IV) the active transport of solutes V) bulk flow from source to sink
A) II, III, IV, and V
B) I, III, IV, and V
C) I, II, IV, and V
D) I, II, III, and V
C) be in both directions and the concentrations would remain equal
D) occur only as ATP was hydrolyzed in the tissue
Loss of water from the aerial parts of plants is called ________.
A) dehydration
B) respiration
C) gas exchange
D) transpiration
Which of the following contribute to the surface area available for water absorption from the soil by a plant root system?
I) root hairs II) endodermis III) mycorrhizae IV) fibrous arrangement of the roots
A) II and III
B) I, III, and IV
C) I, II, and IV
D) I, II, III, and IV
What is the overall charge on the cytoplasmic side of a plant cell plasma membrane?
A) positive
B) negative
C) neutral
A water molecule could move all the way through a plant from soil to root to leaf to air and pass through a living cell only once. This living cell would be a part of which structure?
A) a guard cell
B) the root epidermis
C) the endodermis
D) the root cortex
Bulk flow is much faster than diffusion or active transport. Peak velocities in the transport of xylem sap can range from ________ for trees with wide vessel elements.
A) 10-20 m/hr
B) 15-45 m/hr
C) 5-10 m/hr
D) >50 m/hr
In plant roots, the Casparian strip ________.
A) aids in the uptake of nutrients
B) provides energy for the active transport of minerals into the stele from the cortex
C) ensures that all minerals are absorbed from the soil in equal amounts
D) ensures that all water and dissolved substances must pass through a cell membrane before entering the stele
Which of the following observations provides the strongest evidence against root pressure being the principal mechanism of water transport in the xylem?
A) Not all soils have high concentrations of ions.
B) Root pressure requires movement of water into the xylem from surrounding cells in the roots.
C) Over long distances, the force of root pressure is not enough to overcome the force of gravity.
D) There is no water potential gradient between roots and shoots.
One is most likely to see guttation in small plants when the ________.
A) transpiration rates are high
B) root pressure exceeds transpiration pull
C) preceding evening was hot, windy, and dry
D) roots are not absorbing minerals from the soil
Most of the water taken up by a plant is ________.
A) used as a solvent
B) used as a hydrogen source in photosynthesis
C) lost during transpiration
D) used to keep cells turgid
Transpiration in plants requires ________.
I) adhesion of water molecules to cellulose II) cohesion between water molecules III) evaporation of water molecules IV) active transport through xylem cells V) transport through tracheids
A) I, III, IV, and V
B) I, II, IV, and V
C) I, II, III, and V
During the nighttime, due to lack of transpiration, the water potential within the vascular cylinder ________.
A) lowers due to accumulation of minerals
B) increases due to accumulation of minerals
C) lowers due to loss of minerals
D) increases due to loss of minerals
What is the main force by which most of the water within xylem vessels moves toward the top of a tree?
A) active transport of ions into the stele
B) evaporation of water through stoma
C) the force of root pressure
D) osmosis in the root
Water potential is generally most negative in which of the following parts of a plant?
A) mesophyll cells of the leaf
B) xylem vessels in leaves
C) xylem vessels in roots
D) cells of the root cortex
Formation of the curved upper surface, such as occurs in a tube filled with water, is an important factor in plant water movement. A curved upper surface is created by ________.
A) the upward pull of gravity on the water column in the tube
B) downward pressure from the atmosphere on the topmost layer of water molecules
C) the water molecules being pulled upward by adhesion to the air
D) the topmost layer of water molecules being pulled downward by the hydrogen bonds to the water molecules below
Which one of the following ions plays a critical role in the opening and closing of stomata?
Which of the following primarily enters a plant somewhere other than through the roots?
A) carbon dioxide
B) nitrogen
C) potassium
D) water
The opening of stomata is thought to involve ________.
A) an increase in the solute concentration of the guard cells
B) active transport of water out of the guard cells
C) decreased turgor pressure in guard cells
D) movement of K+ from the guard cells
The high surface-to-volume ratio in leaves aids in ________.
A) more light absorption
B) less light absorption
C) CO2 absorption
Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of an oak tree?
A) a cool, dry day
B) a very hot, dry, windy day
C) a warm, humid day
D) a cool, humid day
Photosynthesis ceases when leaves wilt, mainly because ________.
A) the chlorophyll in wilting leaves is degraded
B) flaccid mesophyll cells are incapable of photosynthesis
C) stomata close, preventing carbon dioxide from entering the leaf
D) accumulation of carbon dioxide in the leaf inhibits enzymes
The water lost during transpiration is a side effect of the plant's exchange of gases. However, the plant derives some benefit from this water loss in the form of ________.
A) increased turgor and increased growth
B) mineral transport and increased growth
C) evaporative cooling and increased turgor
D) evaporative cooling and mineral transport
Which of the following experimental procedures would most likely reduce transpiration while allowing the normal growth of a plant?
A) subjecting the leaves of the plant to a partial vacuum
B) increasing the level of carbon dioxide around the plant
C) putting the plant in drier soil
D) decreasing the relative humidity around the plant
Several tomato plants are growing in a small garden plot. If soil water potential were to drop significantly on a hot, summer afternoon, which of the following would most likely occur?
A) Size of stomatal openings would decrease.
B) Transpiration would increase.
C) The leaves would become more turgid.
D) The uptake of carbon dioxide would be enhanced.
What is the advantage of having small, needlelike leaves?
A) increased transpiration rate
B) decreased transpiration rate
C) increased efficiency of light capture
D) decreased efficiency of light capture
The plant hormone ________ causes stomatal closures in drought stress conditions.
A) indole-3-acetic acid
B) gibberellin
C) abscisic acid (ABA)
D) ethylene
Plants adapted to arid environments are referred to as ________.
A) mesophytes
B) xerophytes
C) psilophytes
D) halophytes
In xerophytes, ________ are referred to as crypts.
A) stomata recessed in cavities
B) guard cells
C) hairs (trichomes)
D) lower epidermal cells
Which of the following is a net sugar source for a deciduous angiosperm tree?
A) new leaves in early spring
B) fruits in summer
C) roots in early spring
D) roots in early autumn
Arrange the following five events in an order that explains the mass flow of materials in the phloem.
1. Water diffuses into the sieve tubes. 2. Leaf cells produce sugar by photosynthesis. 3. Solutes are actively transported into sieve tubes. 4. Sugar is transported from cell to cell in the leaf. 5. Sugar moves down the stem.
A) 1, 2, 3, 4, 5
B) 2, 4, 3, 1, 5
C) 4, 2, 1, 3, 5
D) 2, 4, 1, 3, 5
Water flows into the source end of a sieve tube because ________.
A) sucrose has been actively transported into the sieve tube, making it hypertonic
B) water pressure outside the sieve tube forces in water
C) the companion cell of a sieve tube actively pumps in water
D) sucrose has been transported out of the sieve tube by active transport
Which of the following supports the finding that sugar translocation in phloem is an active (energy-requiring) process?
A) Sucrose occurs in higher concentrations in companion cells than in the mesophyll cells where it is produced.
B) Movement of water occurs from xylem to phloem and back again.
C) Strong pH differences exist between the cytoplasm of the companion cell and the mesophyll cell.
D) ATPases are abundant in the plasma membranes of the mesophyll cells.
Which one of the following statements about transport of nutrients in phloem is correct?
A) Solute particles are actively transported from phloem at the source.
B) Companion cells control the rate and direction of movement of phloem sap.
C) Differences in osmotic concentration at the source and sink cause a hydrostatic pressure gradient to be formed.
D) A sink is the part of a plant where a particular solute is produced.
In the pressure-flow mechanism, loading of sucrose from companion cells to sieve-tube elements takes place through ________.
A) plasmodesmata
B) facilitated diffusion
C) sucrose-H+ symporters
D) sucrose-H+ antiporters
Which of the following is a correct statement about sugar movement in phloem?
A) Diffusion can account for the observed rates of transport.
B) Movement can occur both upward and downward in the plant.
C) Sugar is translocated from sinks to sources.
D) Only phloem cells with nuclei can perform sugar movement.
Plants do not have a circulatory system like that of some animals. If a water molecule in a plant did "circulate" (that is, go from one point in a plant to another and back in the same day), it would require the activity of ________.
A) only the xylem
B) only the phloem
C) only the endodermis
D) both the xylem and the phloem
Some botanists argue that the entire plant should be considered as a single unit rather than a composite of many individual cells. Which of the following cellular structures best supports this view?
A) cell wall
B) cell membrane
C) vacuole
D) plasmodesmata
Plasmodesmata can change in number, and when dilated can provide a passageway for ________.
A) macromolecules
B) ribosomes
C) chloroplasts
D) mitochondria
The symplastic route can transport ________.
A) sugars, mRNA, and mitochondria
B) mRNA, mitochondria, and proteins
C) mitochondria, mRNA, and viruses
D) viruses, sugars, and mRNA
Which of the following is an adaptation that enhances the uptake of water and minerals by roots?
A) mycorrhizae
B) pumping through plasmodesmata
C) active uptake by vessel elements
D) rhythmic contractions by cells in the root cortex
Which structure or compartment is part of the symplast?
A) the interior of a vessel element
B) the interior of a sieve tube
D) an extracellular air space
Movement of phloem sap from a source to a sink
A) occurs through the apoplast of sieve-tube elements.
B) depends ultimately on the activity of proton pumps.
C) depends on tension, or negative pressure potential.
D) results mainly from diffusion.
Photosynthesis ceases when leaves wilt, mainly because
A) the chlorophyll in wilting leaves is degraded.
B) accumulation of CO2 in the leaf inhibits enzymes.
C) stomata close, preventing CO2 from entering the leaf.
D) photolysis, the water-splitting step of photosynthesis, cannot occur when there is a water deficiency.
What would enhance water uptake by a plant cell?
A) decreasing the Ψ of the surrounding solution
B) positive pressure on the surrounding solution
C) the loss of solutes from the cell
D) increasing the Ψ of the cytoplasm
A plant cell with a ΨS of -0.65 MPa maintains a constant volume when bathed in a solution that has a ΨS of -0.30 MPa and is in an open container. The cell has a
A) ΨP of +0.65 MPa.
B) Ψ of -0.65 MPa.
C) ΨP of +0.35 MPa.
D) ΨP of 0 MPa.
Compared with a cell with few aquaporin proteins in its membrane, a cell containing many aquaporin proteins will
A) have a faster rate of osmosis.
B) have a lower water potential.
C) have a higher water potential.
D) accumulate water by active transport.
Which of the following would tend to increase transpiration?
A) spiny leaves
B) sunken stomata
C) a thicker cuticle
D) higher stomatal density
The circulatory systems of bony fishes, rays, and sharks are most similar to ________.
A) those of birds, with a four-chambered heart
B) the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber
C) those of sponges, where gas exchange in all cells occurs directly with the external environment
D) those of humans, where there are four pumping chambers to drive blood flow
Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have ________.
A) an open circulatory system
B) a closed circulatory system
C) a gastrovascular cavity
D) branched tracheae
In which of the following organisms does blood flow from the pulmocutaneous circulation to the heart before circulating through the rest of the body?
A) annelids
B) fishes
C) frogs
D) insects
The only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the ________.
A) amphibians
C) mammals
D) reptiles
To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n) ________.
A) open circulatory system
B) hemocoel
C) two-chambered heart
D) four-chambered heart
An anthropologist discovers the fossilized heart of an extinct animal. The evidence indicates that the organism's heart was large, was well-formed, and had four chambers, with no connection between the right and left sides. A reasonable conclusion supported by these observations is that the ________.
A) animal had evolved from birds
B) animal was endothermic and had a high metabolic rate
C) animal was most closely related to alligators and crocodiles
D) species had little to no need to regulate blood pressure
In an open circulatory system, blood is ________.
A) always inside of vessels and is under higher pressure than in closed circulatory systems
B) not always confined to blood vessels and is under higher pressure than in closed circulatory systems
C) always inside of vessels and is under lower pressure than in closed circulatory systems
D) not always confined to blood vessels and is under lower pressure than in closed circulatory systems
Circulatory systems compensate for ________.
A) temperature differences between the lungs and the active tissue
B) the slow rate at which diffusion occurs over large distances
C) the problem of communication systems involving only the nervous system
D) the need to cushion animals from trauma
Which of the following develops the greatest pressure on the blood in the mammalian aorta?
A) systole of the left atrium
B) diastole of the right ventricle
C) systole of the left ventricle
D) diastole of the right atrium
Which of the following is the correct sequence of blood flow in birds and mammals?
A) left ventricle → aorta → lungs → systemic circulation
B) vena cava → right atrium → right ventricle → pulmonary vein
C) pulmonary vein → left atrium → left ventricle → pulmonary circuit
D) vena cava → right atrium → right ventricle → pulmonary artery
A patient with a heart rate of 70 beats per minute and a stroke volume of 70 mL/beat will have a cardiac output of ________.
A) 1,000 mL/minute
B) 1,400 mL/minute
C) 2,800 mL/minute
D) 4,900 mL/minute
Damage to the sinoatrial node in humans would ________.
A) block conductance between the bundle branches and the Purkinje fibers
B) have a negative effect on peripheral resistance
C) disrupt the rate and timing of cardiac muscle contractions
D) have a direct effect on blood pressure monitors in the aorta
While jogging, a person has a stroke volume of 130 ml/beat and a heart rate of 120 beats per minute. If their resting stroke volume was 70 ml/beat and resting heart rate was 60 beats per minute, how did this person's cardiac output change?
A) Their cardiac output did not change. Only their respiratory rate changed.
B) During exercise, their cardiac output decreased by 11,400 ml/minute.
C) During exercise, their cardiac output increased by 60 ml/beat.
D) Their cardiac output increased from 4,200 ml/minute to 15,600 ml/minute after jogging.
Atrial systole ________.
A) occurs at the same time as ventricular diastole
B) pumps blood to the aorta
C) refers to the relaxation of the cardiac muscle
D) only occurs in the left heart chambers
The greatest difference in the concentration of respiratory gases is found in which of the following pairs of mammalian blood vessels?
A) the pulmonary vein and the superior vena cava
B) the veins from the right and left legs
C) the pulmonary artery and the inferior vena cava
D) the pulmonary vein and the aorta
A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. To travel from the artery to the thumb and then back to the left ventricle, this red blood cell must pass through ________.
A) one capillary bed
B) two capillary beds
C) three capillary beds
D) four capillary beds
An electrocardiogram (ECG) provides information about ________.
A) the pressure of blood in the heart chambers
B) the rhythm of heart contractions
C) the amount of oxygen in the blood as it leaves the heart
D) the speed of blood flow through the blood vessels
Among the following choices, which organism likely has the highest systolic pressure?
A) mouse
B) human
C) hippopotamus
D) giraffe
The velocity of blood flow is the lowest in capillaries because ________.
A) the capillaries have internal valves that slow the flow of blood
B) the diastolic blood pressure is too low to deliver blood to the capillaries at a high flow rate
C) the systemic capillaries are supplied by the left ventricle, which has a lower cardiac output than the right ventricle
D) the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system
Which of the following would you expect of a species that has a high resting cardiac output?
A) The animal is likely small and compact, without the need to pump blood very far from the heart.
B) The species likely has very wide-diameter veins.
C) The animal likely has a very long distance between its heart and its brain.
D) The animal likely has a relatively inactive lifestyle.
Small swollen areas in the neck, groin, and axillary region are associated with ________.
A) increased activity of the immune system
B) blood sugar that is abnormally high
C) dehydration
D) sodium depletion
Humans infected with some types of parasitic worms develop a condition called elephantiasis, which is characterized by swelling of the limbs. Which of the following would be the most likely cause of elephantiasis?
A) The infected human's immune system is fighting the worms.
B) The worm infection is causing a decrease in cardiac output.
C) The worms are blocking the lymph vessels.
D) More blood is flowing through precapillary sphincters.
Which of the following conditions would most likely be due to high blood pressure in a mammal?
A) bursting of blood vessels in capillary beds
B) inability of the right ventricle to contract
C) reversal of normal blood flow direction in arteries
D) destruction of red blood cells
Which of the following mechanisms are used to regulate blood pressure in the closed circulatory system of vertebrates?
I) changing the force of heart contraction II) constricting and relaxing smooth muscle in the walls of arterioles III) opening or closing precapillary sphincters
A) only I and II
B) only I and III
C) only II and III
D) I, II, and III
Blood is pumped at high pressures in arteries from the heart to ensure that all parts of the body receive adequate blood flow. Capillary beds, however, would hemorrhage under direct arterial pressures. How does the design of the circulatory network contribute to reducing blood pressure to avoid this scenario?
A) Blood flow through the capillaries is essentially frictionless, and this reduces the amount of pressure on their walls.
B) The total cross-sectional diameter of the arterial circulation increases with progression from artery to arteriole to capillary, leading to a reduced blood pressure.
C) Fluid loss from the arteries is high enough that pressure drops off significantly by the time blood reaches the capillaries.
D) Capillary beds have the thickest walls of any blood vessel to resist these high pressures.
In order for blood to always flow unidirectionally through a closed circulatory system, the ________.
A) blood vessels farthest from the heart must have valves
B) capillaries must have a thick endothelium
C) arteries must be elastic
D) pressure in all vessels must be equal
If the osmotic pressure on the venous side of capillary beds is lower than the hydrostatic pressure, then ________.
A) hemoglobin will not release oxygen
B) fluid will tend to accumulate in tissues
C) the pH of the interstitial fluids will increase
D) plasma proteins will escape through the endothelium of the capillaries
Large proteins such as albumin remain in capillaries rather than diffusing out, resulting in the ________.
A) loss of osmotic pressure in the capillaries
B) development of an osmotic pressure difference across capillary walls
C) loss of fluid from capillaries
D) increased diffusion of hemoglobin
Blood cells that function to fight infection are called ________.
A) platelets
B) leukocytes
C) erythrocytes
D) thrombi
To become bound to hemoglobin for transport in mammals, atmospheric molecules of oxygen must cross ________.
A) one membrane—that of the lining in the lungs—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
B) two membranes—in and out of the cell lining the lung—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
C) four membranes—in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood
D) five membranes—in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary, and into the red blood cell—to bind with hemoglobin
The diagnosis of hypertension in adults is based on the ________.
A) measurement of fatty deposits on the endothelium of arteries
B) measurement of the LDL/HDL ratio in peripheral blood
C) percentage of blood volume made up of platelets
D) blood pressure being greater than 140 mm Hg systolic and/or greater than 90 mm Hg diastolic
Cyanide poisons mitochondria by blocking the final step in the electron transport chain. Human red blood cells placed in an isotonic solution containing cyanide are likely to ________.
A) retain the normal cell shape, but the mitochondria will be poisoned
B) lyse as the cyanide concentration increases inside the cell
C) switch to anaerobic metabolism
D) be unaffected
A normal event in the process of blood clotting is the ________.
A) production of erythropoietin
B) conversion of fibrin to fibrinogen
C) activation of prothrombin to thrombin
D) synthesis of hemoglobin
You cut your finger, and after putting pressure on the wound for several minutes, you notice that it is still bleeding profusely. What may be the problem?
A) Platelets are not functioning properly, or there are too few to be effective.
B) Mast cells are not releasing their chemical messengers.
C) There are too many antigens to allow clotting.
D) Hemoglobin levels are too high to allow clotting.
________ is a hormone that is released from the ________ to stimulate the production of red blood cells.
A) Growth hormone; pancreas
B) Erythropoietin; kidney
C) Cortisol; adrenal gland
D) Acetylcholine; bone marrow
Countercurrent exchange is evident in the flow of ________.
A) water across the gills of a fish and the blood within those gills
B) blood in the dorsal vessel of an insect and that of air within its tracheae
C) air within the primary bronchi of a human and the blood within the pulmonary veins
D) water across the skin of a frog and the blood flow within the ventricle of its heart
37) Countercurrent exchange in the fish gill helps to maximize ________.
A) blood pressure
B) diffusion
C) active transport
D) osmosis
Which of the following statements comparing respiration in fish and in mammals is correct?
A) The respiratory medium for fish carries more oxygen than the respiratory medium of mammals.
B) A countercurrent exchange mechanism between the respiratory medium and blood flow is seen in mammals but not in fish.
C) The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional.
D) In blood, oxygen is primarily transported by plasma in fish, but by red blood cells in mammals.
Although having evolved independently, the tracheal tubes of mammals and insects are both supported by rigid tissues. The trachea of a mammal is supported by cartilage, and the tracheae of an insect are supported by chitin. What selective pressure most likely led to the convergent evolution of these respiratory structures?
A) Both mammals and insects have similar oxygen needs.
B) When air is the respiratory medium, there is a greater risk that the tracheal tubes will collapse.
C) Insects and mammals both keep their internal temperature constant.
D) A decrease in environmental carbon dioxide made structural support necessary.
When the air in a testing chamber is specially mixed so that its oxygen content is 10% and its overall air pressure is 400 mm Hg, then PO2 is ________.
A) 400 mm Hg
B) 82 mm Hg
C) 40 mm Hg
D) 4 mm Hg
The sun shining on a tidal pool during a hot day heats the water, causing some water to evaporate. Because the water has become warmer and saltier, ________.
A) the carbon dioxide content will increase
B) the oxygen content will decrease
C) it will be better able to sustain aerobic organisms
D) it will become more dense
An oil-water mixture works as an insecticidal spray against mosquitoes and other insects because it ________.
A) blocks the openings into the tracheal system
B) interferes with gas exchange across the capillaries
C) clogs their bronchi
D) prevents gases from leaving the atmosphere
Atmospheric pressure at the summit of Mount Everest is about one third the pressure at sea level, which is 760 mm Hg. If oxygen makes up 21% of the atmosphere by volume, the partial pressure of oxygen (PO2) on Mount Everest is approximately ________.
A) 53 mm Hg
B) 157 mm Hg
C) 255 mm Hg
D) 760 mm Hg
Some human infants, especially those born prematurely, suffer serious respiratory failure because of ________.
A) the sudden change from the uterine environment to the air
B) the overproduction of surfactants
C) lung collapse due to inadequate production of surfactant
D) mutations in the genes involved in lung formation
Which of the following represents the correct flow of air into the lung of a mammal?
A) trachea → bronchioles → bronchi → alveoli
B) larnyx → trachea → bronchi → bronchioles → alveoli
C) trachea → tracheoles → bronchi → alveoli
D) alveoli → tracheoles → bronchi → trachea
During aerobic exercise, the partial pressure of oxygen in muscle cells will ________, thus the rate of diffusion of oxygen into the muscle tissue from the blood will ________.
A) decrease; increase
B) increase; decrease
C) not change; also not change
D) decrease; decrease
A rabbit taken from a meadow near sea level and moved to a meadow high on a mountainside would have some trouble breathing. Why?
A) The percentage of oxygen in the air at high elevations is lower than at sea level.
B) The percentage of oxygen in the air at high elevations is higher than at sea level.
C) The partial pressure of oxygen in the air at high elevations is lower than at sea level.
D) The partial pressure of oxygen in the air at high elevations is higher than at sea level.
What would be the consequence if we were to reverse the direction of water flow over the gills of a fish, moving water inward past the operculum, past the gills, then out the mouth? This reversal of water flow would ________.
A) reduce efficiency of gas exchange
B) change the exchange of gases in the body from carbon dioxide out and oxygen in to carbon dioxide in and oxygen out
C) increase the efficiency of gas exchange
Under identical atmospheric conditions, freshwater ________.
A) has more dissolved oxygen than seawater
B) has less dissolved oxygen than seawater
C) can hold 10-40 times more carbon dioxide than air
D) can hold 10-40 times more oxygen than air
Consider the following reaction. If the pH of the blood was decreased, then the ________.
CO2 + H2O --> H2CO3 --> HCO3- + H+
A) amount of carbon dioxide would increase
B) bicarbonate in the blood would increase
C) amount of oxygen in the blood will decrease
D) amount of protons in the blood will increase
How has the avian lung adapted to the metabolic demands of flight?
A) Airflow through the avian lung is bidirectional like in mammals.
B) There is more dead space within the avian lung so that oxygen can be stored for future use.
C) Countercurrent circulation is present in the avian lung.
D) Gas exchange occurs during both inhalation and exhalation.
Carbon dioxide levels in the blood and cerebrospinal fluid affect pH. This enables the organism to sense a disturbance in gas levels as ________.
A) the brain directly measures and monitors oxygen levels and causes breathing changes accordingly
B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing
C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide
D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing
A person with a tidal volume of 450 mL (milliliters), a vital capacity of 4000 mL, and a residual volume of 1000 mL would have a potential total lung capacity of ________.
A) 1450 mL
B) 4000 mL
C) 4450 mL
D) 5000 mL
During most daily activities, the human respiration rate is most closely linked to the blood levels of ________.
A) nitrogen
B) oxygen
C) carbon dioxide
D) carbon monoxide
A decrease of blood pH from 7.4 to 7.2 causes hemoglobin to ________.
A) release all bound carbon dioxide molecules
B) bind more oxygen molecules
C) decrease its binding of H+
D) give up more of its oxygen molecules
Most of the carbon dioxide produced by humans is ________.
A) converted to bicarbonate ions
B) bound to hemoglobin
C) transported in the erythrocytes as carbonic acid
D) simply dissolved in the plasma
Which of the following events would you predict as carbon dioxide is released from your muscles into the surrounding capillary bed?
A) Oxygen delivery to muscle is increased when more carbon dioxide is produced by the muscle.
B) Because of the change in blood pH, the blood can carry more oxygen.
C) The amount of oxygen in venous blood will increase.
D) Arterial blood entering the capillaries will carry more oxygen.
Compared to mammals that are not adapted for diving, diving mammals ________.
A) have larger lungs
B) can store more oxygen in their muscles
C) use gills for gas exchange
D) always keep blood flowing to their lungs during a dive
Hyperventilation (rapid inhalation and exhalation) can result in respiratory alkalosis (increased blood pH). Why?
A) Hyperventilation results in inefficient gas exchange, and not enough oxygen is absorbed by the blood.
B) More metabolic waste is released into the blood, thus reducing the pH.
C) Rapid breathing depletes the blood of carbon dioxide, thus the blood pH increases.
D) Excess production of carbon dioxide decreases the affinity of hemoglobin for oxygen.
Which of the following respiratory systems is not closely associated with a blood supply?
A) the lungs of a vertebrate
B) the gills of a fish
C) the tracheal system of an insect
D) the skin of an earthworm
Blood returning to the mammalian heart in a pulmonary vein drains first into the
A) left atrium.
B) right atrium.
C) left ventricle.
D) right ventricle.
Pulse is a direct measure of
A) blood pressure.
B) stroke volume.
C) cardiac output.
D) heart rate.
When you hold your breath, which of the following blood gas changes first leads to the urge to breathe?
A) rising O2
B) falling O2
C) rising CO2
D) falling CO2
One feature that amphibians and humans have in common is
A) the number of heart chambers.
B) a complete separation of circuits for circulation.
C) the number of circuits for circulation.
D) a low blood pressure in the systemic circuit.
If a molecule of CO2 released into the blood in your left toe is exhaled from your nose, it must pass through all of the following except
A) the pulmonary vein.
B) the trachea.
C) the right atrium.
D) the right ventricle.
Compared with the interstitial fluid that bathes active muscle cells, blood reaching these cells in arterioles has a
A) higher PO2.
B) higher PCO2.
C) greater bicarbonate concentration.
D) lower pH.
