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Chapter 2 Physiological Evolution of Animals
1) Which of the following is a parasitic protist that causes malaria?
Answer: D
Page ref: 22
2) Which of the following characteristics apply to all protists?
Answer: C
Page ref: 22
3) Which protist is best described by its lifestyle?
Answer: B
Page ref: 22
4) Which of the following pairs is correctly matched?
Answer: D
Page ref: 23
5) If multicellular organisms have distinct cell types, this means that
Answer: A
Page ref: 23
6) In fungi and plants
Answer: A
Page ref: 23-24
7) All animals
Answer: B
Page ref: 24
8) The three cell types found in sponges are
Answer: B
Page ref: 24
9) The first animals to show true tissues were
Answer: C
Page ref: 24
10) One key advantage associated with bilateral symmetry in animals is
Answer: D
Page ref: 25
11) In early gastrulation, a depression called a blastopore forms. If this blastopore forms the anus, the animals are referred to as
Answer: A
Page ref: 25
12) Which of the following statements is correct?
Answer: C
Page ref: 25-28
13) Triploblastic animals are
Answer: C
Page ref: 26
14) Platyhelminthes exhibit which of the following lifestyles?
Answer: D
Page ref: 26
15) Platyhelminthes can live without a circulatory or respiratory system because
Answer: B
Page ref: 27
16) Which of the following statements best describes mollusks?
Answer: A
Page ref: 27
17) Which characteristics do annelids and arthropods have in common?
Answer: C
Page ref: 27-28
18) Which of the following characteristics would be most beneficial for animals to successfully survive on land?
Answer: D
Page ref: 27-28
19) The most ancient deuterostomes are
Answer: B
Page ref: 28
20) Ganss and Northcutts new head hypothesis proposes that
Answer: C
Page ref: 28
21) Cartilaginous fish evolved from
Answer: B
Page ref: 29
22) Amphibians differ from other tetrapods in that amphibians
Answer: C
Page ref: 31
23) Which of the following animals are amniotes?
Answer: C
Page ref: 31
24) Which of the following pairs is correctly matched?
Answer: B
Page ref: 31
25) In terms of reproduction, which group of mammals is most similar to their reptilian ancestors?
Answer: A
Page ref: 32
26) Which of the following statements correctly describes birds?
Answer: D
Page ref: 32
27) Birds and mammals are similar in that
Answer: D
Page ref: 32
28) Would you expect gene duplication, such as seen in the Hox gene, to lead to significant changes in evolution of traits?
Answer: C
Page ref: 33
29) Which of the following statements is true with respect to myosin?
Answer: C
Page ref: 33
30) Only certain organisms possess gene variants that are able to exchange Na+ for K+, thus making the Na+/K+ ATPase unique to
Answer: A
Page ref: 34
31) Collagen is best described as a(n)
Answer: B
Page ref: 35
32) In tetrapods, the steroid hormone, aldosterone, plays a role in
Answer: D
Page ref: 35
33) One of the biggest challenges facing terrestrial organisms is to
Answer: C
Page Ref: 36
34) Which of the following organisms are able to thrive under the most diverse environmental conditions due to their remarkable biochemical adaptations?
Answer: A
Page ref: 36
35) Which of the following statements with respect to animals is correct?
Answer: B
Page Ref: 36
36) The __________ is considered to be the earliest life form.
Answer: progenote
Page Ref: 21
37) ____________ are often called extremophiles, because they can survive in some of the harshest environments on earth.
Answer: Archaea
Page Ref: 21
38) The cell wall of fungi is composed of ____________.
Answer: chitin
Page Ref: 23
39) The tissues of Cnidarians are termed _____________ because they are derived from two embryonic body layers.
Answer: diploblastic
Page Ref: 24
40) The body plan of sponges is _____________, while cnidarians are ______________________.
Answer: asymmetrical; radially symmetrical
Page Ref: 25
41) The body of annelids is divided into repeating segments called_________________.
Answer: metamers
Page Ref: 27
42) In echinoderms and chordates, the mouth forms second; therefore, both are__________________.
Answer: deuterostomes
Page Ref: 25, 28
43) The first group of vertebrates to successfully colonize land was the __________________.
Answer: amphibians
Page Ref: 31
44) In reptiles and birds, the evolution of the _____________ removed the dependence on water and allowed complete transition to life on land.
Answer: amniote egg
Page Ref: 32
45) Birds are most closely related to the group of reptiles known as ________________.
Answer: archosaurs
Page Ref: 32
46) Which family of genes is involved in development?
Answer: Hox
Page Ref: 33
47) Many eukaryotes have myosin 2, but only __________ use it to build muscle.
Answer: animals
Page ref: 33
48) The Na+/K+ ATPase enables animal cells to create an electrical potential across the_________.
Answer: cell membrane
Page Ref: 35
49) Aldosterone is a steroid hormone that is produced only in ____________.
Answer: tetrapods
Page Ref: 35
50) Metabolic rate is measured as ___________________.
Answer: heat production per unit time
Page Ref: 36
51) We often hear the terms protists, protozoans, and metazoans; briefly explain the relationship among them.
Answer: When we think about the origin of animals, we often think of protists. Protists are single-celled, eukaryotic organisms that possess a membrane-bound nucleus and organelles. Protists are a very diverse group of distantly-related organisms, and hence assigned to more than 50 phyla. Some protists are animal-like and mobile, and because locomotion was considered a unique trait of animals, animal-like protists were once considered to be the ancestors of animals and were referred to as protozoans. Currently, the term protozoan has no meaningful evolutionary basis. The term metazoan was originally created to differentiate single-celled protozoans from multicellular animals. Metazoan and animal are often used synonymously.
Page Ref: 22
52) List the four key morphological traits that characterize all chordates. Discuss the important physiological transitions from early chordates to Craniata and their evolutionary implication.
Answer: All chordates have a notochord, dorsal nerve cord, postanal tail, and pharyngeal slits.
When we compare early chordates to Craniata, we see several physiological transitions such as an increase in the complexity of the nervous system, the formation of a larger brain, a backbone derived from the notochord, an endoskeleton with the cranium, segmented muscles, and large blood vessels. The filter-feeding pharyngeal structures in lancelets and tunicates evolved into a diversity of structures, including gills of fish, jawbones, ear bones, muscles, nerves, and blood vessels. The evolution of these structures resulted in an extensive diversity of vertebrates.
Page Ref: 28
53) From an evolutionary perspective, briefly explain why amphibian physiology provides an important link between aquatic and terrestrial organisms.
Answer: Amphibians are intermediate between fish and reptiles in several ways. For example, amphibian larvae are aquatic and breathe via gills, just like fish. When in water, adult amphibians face similar osmotic challenges as do freshwater fish. Unlike fish, adult amphibians use lungs to breathe on land, may also use their skin as a gas-exchange surface, and excrete urea as a waste product. We see similarities between amphibians and reptiles when it comes to skeletons and muscles: Land tetrapods require more robust skeletons and musculature to support their bodies on land. Some amphibians, such as toads, have evolved a thickened body covering to avoid desiccation. Reptiles are even better adapted to dry conditions, having evolved tough scales to prevent water loss.
Page Ref: 31
54) Why is the sodium-potassium pump so important in the animal kingdom?
Answer: The sodium-potassium pump is also known as Na+/K+ ATPase. It is unique to animals because only animals possess the gene variants that can exchange Na+ for K+. In animal cells, the sodium-potassium pump creates an electrical potential across cell membranes and maintains the membrane ion gradients that are critical for the function of neurons and muscles. Sodium-potassium genes also allow for adaptations in relation to osmoregulation. For example, some species of fish can change the expression of their Na+/K+ ATPase genes when they change environments, thus allowing them to successfully move between freshwater and salt water at specific times in their life cycle.
Page Ref: 33-35
55) Discuss the evolutionary connection between bilateral symmetry and cephalization in animals.
Answer: As organisms became more complex, this complexity was associated with an increase in cephalization. Very early animals had simple nervous systems with little centralization for processing information. Bilaterally symmetrical animals show a concentration of sensory and nervous tissue in the anterior parts of their bodies. With the evolution of bilateral symmetry, animals were able to move in a forward direction, using the sensory anterior end to locate food or sense threats. For example, arthropods, which are bilaterally symmetrical, have a distinct head region that processes extensive sensory information. Vertebrates show even more extensive cephalization. In mammals, for example, the brain and central nervous system control breathing, feeding, reflexes, thermoregulation, and movement.
Page Ref: 36
56) Describe some key physiological adaptations that allowed animals to successfully colonize terrestrial environments.
Answer: Animals had to evolve physiological adaptations to successfully invade terrestrial environments. Desiccation is a risk for all land organisms, therefore, adaptations to conserve water were critical. Animals also had to overcome the challenge of controlling their internal osmolarity, independent of the external environment. Animals evolved a body surface that would prevent water loss (e.g., reptilian scales). An excretory system used to expel nitrogenous wastes out of water was also an important adaptation for land animals. When water was no longer available for support, skeletons and muscles evolved to allow locomotion on land. In addition, respiratory systems to exchange gases on land became a requirement for successful survival on land.
Page Ref: 36
Chapter 4 Cell Signaling and Endocrine Regulation
1)
Which of the following statements is true of any communication system?
Neurons are always involved.
The endocrine system is always involved.
A signal must always be sent and received.
Signals can be sent only in electrical form.
Answer:
C
Page Ref: 98
2)
Which of the following choices is not a basic feature of cellular communication?
The signal must be produced.
The signal can be produced only by a eukaryote.
The signal must be transported to a target cell.
The target cell must respond to the signal.
Answer:
B
Page Ref: 99
3)
It is possible for cells to communicate directly (via a connection of the cytoplasm) with each other by using
gap junctions.
paracrine signaling.
endocrine signaling.
autocrine signaling.
Answer:
A
Page Ref: 99
4) Which of the following statements provides inaccurate information?
Answer: D
Page Ref: 100
5)
When chemical signals are sent between two animals, __________ communication is being used.
neural
endocrine
autocrine
exocrine
Answer:
D
Page Ref: 102
6)
Gap junctions are formed by
groups of 8-12 connexons making a pore in one cell.
groups of 4-6 innexins or connexins forming a pore in one cell.
connexons from adjacent cells connecting with each other to form a cytoplasmic bridge.
both A and C
both B and C
Answer:
E
Page Ref: 101
7)
When indirect signaling is used, the target cell responds to the signal when that chemical
binds to an enzyme.
binds to a receptor.
binds to a gene.
binds to the nuclear membrane.
Answer:
B
Page Ref: 102
8)
Neural signaling is different from other types of long-distance signaling because
it involves the release of chemical signals.
it involves the use of receptors.
the signal is contained within a single cell as it travels the long distance.
it relies on the blood to carry the signal from one cell to the next.
Answer:
C
Page Ref: 102
9)
A chemical is termed a neurohormone when it is
released by a neuron, but travels in the blood like a hormone.
released by an endocrine gland, but binds to receptors on a neuron.
released by neurons and endocrine glands.
known to be involved with communication, but scientists have not concluded which system uses it.
Answer:
A
Page Ref: 102
10)
Exocrine secretions are used to communicate between different animals and
to digest foodstuffs.
to aid in locomotion.
in trapping prey.
all of the above
Answer:
D
Page Ref: 103
11)
Peptide hormones (chains of 50 or fewer amino acids) are first synthesized as
the hormone itself.
prehormones.
prohormones.
preprohormones.
Answer:
D
Page Ref: 104
12)
The portion of the transmembrane receptor that binds to hydrophilic messengers is termed the
receptor-binding domain.
transmembrane domain.
ligand-binding domain.
intracellular domain.
Answer:
C
Page Ref: 105
13)
The vertebrate hormones involved in water and electrolyte balance in the body are called
mineralocorticoids.
glucocorticoids.
ecdysteroids.
reproductive hormones.
Answer:
A
Page Ref: 106
14)
__________ is a generalized carrier protein that plays a major role in vertebrate blood.
Globulin
Albumin
Hemoglobin
Cholesterol
Answer:
B
Page Ref: 107
15) Which of the following compounds are endocrine disruptors?
Answer: C
Page Ref: 108
16)
Why do steroids take so long to generate change when they bind to intracellular receptors?
The intracellular receptors have very slow kinetics.
The bound receptors affect gene transcription rates.
The steroid receptor complex activates signal transduction pathways.
The steroid receptor complex must then exit the cell to exert its effects.
Answer:
B
Page Ref: 109
17)
The biogenic amine, __________, is important for invertebrates as a neurotransmitter.
epinephrine
norepinephrine
thyroid hormone
octopamine
Answer:
D
Page Ref: 109
18)
In the thyroid hormones, T3 and T4, the 3 and 4 refer to the
relative half-life (3 or 4 hours).
number of tyrosine molecules linked together.
number of iodines which are found on the hormone.
number of enzymes required to synthesize the hormone.
Answer:
C
Page Ref: 110
19)
Eicosanoids are NOT effective as hormones because
they are hydrophobic and cannot dissolve easily in the blood.
they have a very short half-life and would degrade before reaching the target cell.
the signaling cell cannot regulate when they diffuse through the membrane.
all of the above
Answer:
B
Page Ref: 111
20)
Antagonists are compounds that
prevent synthesis of new receptors.
prevent synthesis of hormones.
bind to a receptor, activating it.
bind to a receptor, but do not activate it.
Answer:
D
Page Ref: 113
21)
The response of a cell to a particular chemical messenger is determined by the
ligand-binding domain.
transmembrane domain.
functional domains.
chemical messenger itself.
Answer:
C
Page Ref: 113
22)
Up-regulation of receptors
results in increased sensitivity to its ligand.
results in decreased sensitivity to its ligand.
occurs when a ligand has been present at high levels.
both B and C
Answer:
A
Page Ref: 114-115
23)
A receptor that binds to a ligand at very low concentrations has a
high dissociation constant.
low Ka.
high affinity for the ligand.
low affinity for the ligand.
Answer:
C
Page Ref: 115
24)
The signal transduction cascade acts as the __________ of a transducer.
receiver
transducer
amplifier
responder
Answer:
C
Page Ref: 118-119
25) Which of the following statements is correct?
Answer: A
Page Ref: 119
26)
Which domain of intracellular receptors binds to responsive elements in the nucleus?
DNA-binding domain
transactivation domain
ligand-binding domain
membrane-binding domain
Answer:
A
Page Ref: 119-120
27)
Once a ligand binds to a receptor-enzyme,
the catalytic domain interacts with extracellular components.
the catalytic domain interacts with intracellular components.
the ligand-binding domain is phosphorylated.
the ligand-binding domain is dephosphorylated.
Answer:
B
Page Ref: 121-122
28)
What is the correct relationship between receptor tyrosine kinases and Ras proteins?
Phosphorylated Ras proteins activate the tyrosine kinase.
Phosphorylated Ras proteins pair with a tyrosine kinase to activate other proteins.
Tyrosine kinase dimers phosphorylate the Ras proteins directly.
Tyrosine kinase dimers use GAPs and GNRPs to regulate Ras proteins.
Answer:
D
Page Ref: 123
29)
The G-protein-coupled receptors are a diverse family with this common feature.
They are activated when a kinase molecule phosphorylates them.
They are activated when GTP is released from the G protein.
They are activated when GTP binds to the G protein.
They are activated when the subunit binds to the and subunits.
Answer:
C
Page Ref: 124
30)
Which of the following is NOT a second messenger utilized by G proteins?
Ca2+
Na+
cyclic GMP
phosphatidyl inositol
Answer:
B
Page Ref: 126-127
31)
Phospholipase C cuts membrane phospholipids into
PIP2 and DAG.
PIP2 and IP3.
Ca2+ and DAG.
DAG and IP3.
Answer:
D
Page Ref: 127
32)
Which of the following is different between stimulatory and inhibitory G proteins in the cyclic AMP pathway?
subunit
subunit
subunit
all of the above
Answer:
A
Page Ref: 129
33)
In a feedback loop, the portion that brings the variable back to its normal value is the
effector.
set point.
integrating center.
sensor.
Answer:
A
Page Ref: 133
34)
In a __________ feedback loop, both the endocrine and nervous systems can be involved.
first order
second order
third order
both B and C
Answer:
D
Page Ref: 134-135
35)
The organ that is connected to the hypothalamus by neurons is the
anterior pituitary.
posterior pituitary.
adenohypophysis.
thyroid.
Answer:
B
Page Ref: 135-136
36)
The posterior pituitary is
one of the most important endocrine organs.
an organ producing (not just secreting) neurohormones.
just a physical extension of the hypothalamus.
a very small thin sheet in adult mammals.
Answer:
C
Page Ref: 135-136
37)
The hypothalamic-pituitary portal system transports blood and neurohormones between the
hypothalamus and the heart.
hypothalamus and the pituitary gland (after returning to the heart).
hypothalamus and the posterior pituitary.
hypothalamus and the anterior pituitary.
Answer:
D
Page Ref135-136
38)
Tropic or trophic hormones
are found in tropical organisms.
have the ability to cause other hormones to be released.
are secreted only from the hypothalamus.
both B and C
Answer:
B
Page Ref: 136
39)
Insulin is produced by
Islets of Langerhans in the pancreas.
walls of the intestines.
acinar cells of the pancreas.
red blood cells to help maintain glucose levels.
Answer:
A
Page Ref: 138
40)
Insulin release is NOT stimulated by
CCK.
stretch of the gut.
low blood glucose levels.
high blood glucose levels.
Answer:
C
Page Ref: 138
41)
When two or more hormones are __________, then the response of all the hormones when applied at the same time is greater than the sum of the responses to each hormone applied individually.
antagonistic
additive
synergistic
agonistic
Answer:
C
Page Ref: 139
42)
Epinephrine and norepinephrine are secreted by the
adrenal cortex.
chromaffin cells.
heart.
kidneys.
Answer:
B
Page Ref: 143
43)
What endocrine gland secretes ACTH?
anterior pituitary
posterior pituitary
hypothalamus
adrenal medulla
Answer:
A
Page Ref: 143
44)
__________ are a group of steroid hormones found in all vertebrates.
Estrogens
Androgens
Glucocorticoids
All of the above
Answer:
D
Page Ref: 145
45) The communication and interspecies relationship between the Hawaiian bobtail squid, Euprymna scolopes, and the bacteria, Vibrio fischeri, is one of _____________.
Answer: mutualism
Page Ref: 98-99
46)
A signaling cells message may affect itself as well, in a process known as __________ signaling.
Answer:
autocrine
Page Ref: 99
47)
Chemical messengers used by the endocrine system are referred to as __________.
Answer:
hormones
Page Ref100
48)
In the nervous system, chemical messages cross a __________, a short distance between the signal and target cells.
Answer:
synapse
Page Ref: 102
49)
The three main classes of chemicals that act as hormones are __________, amines, and steroids.
Answer:
peptides
Page Ref104
50)
The term __________ is used for chains more than fifty amino acids long, while the term peptide is reserved for shorter chains.
Answer:
protein
Page Ref: 104
51) The term__________ refers to any molecule that binds specifically to a protein.
Answer: ligand
Page Ref: 105
52)
__________ is a biogenic amine used in immune responses and allergic reactions.
Answer:
Histamine
Page Ref: 110
53)
Nitric oxide is one of three gaseous chemical messengers and is produced by the enzyme __________.
Answer:
nitric oxide synthase (NOS)
Page Ref: 111
54)
When all available receptors have ligand bound to them, we say the receptors are __________.
Answer:
saturated
Page Ref: 114
55)
A signal of one type may be changed to another type of signal using a __________.
Answer:
transducer
Page Ref: 118
56)
When ligand-gated __________ open, ions move in or out of the cell, affecting the membrane potential.
Answer:
ion channels
Page Ref: 121
57)
A G protein with no known ligand or function is termed an __________.
Answer:
orphan receptor
Page Ref: 126
58)
The protein __________ binds four calcium molecules and then interacts with other proteins in the cell, including CaM kinases.
Answer:
calmodulin
Page Ref: 126
59)
__________ is the major hormone secreted by the pineal gland and is involved with circadian and seasonal cycles.
Answer:
Melatonin
Page Ref: 131 (Table 4.4)
60)
__________ is a hormone that is frequently involved with reproductive processes that is also part of a positive feedback loop.
Answer:
Oxytocin (or Estradiol)
Page Ref: 133
61)
In a __________ feedback loop, the endocrine cell acts as the sensor and integrating center.
Answer:
direct
Page Ref: 134
62)
Insulin and __________ are two hormones, produced by the pancreas, with antagonistic control of plasma glucose levels.
Answer:
glucagon
Page Ref: 138
63)
There are multiple ways in which two cells in an organism can communicate with each other: gap junctions, paracrine and autocrine signals, endocrine signals, and neural signals. Discuss the advantages and drawbacks for each of these types of signals.
Answer:
Gap junctions allow direct communication, which is very fast, and allows hydrophilic signals to pass through the aqueous channel. They can be used only with cells that are adjacent to each other. Paracrine and autocrine signals are rapid, but can be used only over short distances because they rely on diffusion. Neural communication is very rapid over long distances, but the signals will not remain effective for a long period of time. Endocrine signals travel more slowly because they rely on a circulatory system for transport, but they remain active for a longer period of time.
Page Ref: 99-103
64)
The chemical properties of messengers affect how they are able to communicate with the target cell. Hydrophobic and hydrophilic messengers have many differences in the way they function. Discuss these differences and how they relate to the hydrophobicity/philicity.
Answer:
Hydrophobic messengers dissolve easily in lipids. Therefore, the membranes are not barriers to them. As a result, they are able to diffuse into a cell and use intracellular receptors, and must be made on demand because they cannot be stored in vesicles. They may also use transmembrane receptors, resulting in more rapid effects. In addition, they must be transported by protein carriers over longer distances because they cannot be dissolved in the blood at high concentrations. Hydrophilic messengers, on the other hand, dissolve easily in the blood and cytosol, but cannot pass through cell membranes. Therefore, they must use transmembrane receptors and can be made ahead and stored in vesicles. They are then exocytosed when it is time for release. Because they bind to transmembrane receptors, their effects are rapid, but many are short-lived.
Page Ref: 103-104
65)
If steroid hormones must be bound to protein carriers to travel through the blood, how are they able to bind to intracellular receptors? (The protein carriers cannot diffuse through the membrane.)
Answer:
Steroid hormones are bound reversibly to their protein carriers, and they are soluble in low concentrations in the blood. When the steroid hormones are produced, there is such a high concentration released that they bind to the protein carriers. For the typical steroid hormone, the majority binds to the protein carrier, but a small amount remains unbound. When the blood passes by the target cell, the free steroid hormone diffuses into the cell to bind to the receptor. This creates an area of decreased concentration of the hormone, so a small amount releases from the carrier protein and is dissolved.
Page Ref: 107, 109
66) What are endocrine disruptors and how do they affect wildlife populations? Provide two examples to support your answer.
Answer: Endocrine disruptors are chemicals that interfere with the endocrine or hormone systems in animals and disrupt normal cell metabolism. Human sewage, which contains chemical pollutants, enters streams, rivers, or lakes, and can negatively affect wildlife populations. Researchers in England discovered that fish living close to the source of the sewage (outfall) had a higher percentage of intersex fish (fish that had both female and male characteristics). High levels of estrogens in the sewage feminized male fish and made them sterile.
Industrial chemicals, such as tributyltin in paint (which is used to keep barnacles from attaching to painted surfaces), are also endocrine disruptors. Tributyltin has been shown to cause a condition called imposex in species of mollusks. Imposex female snails develop a penis that blocks the opening of the oviduct. If most of the eggs cannot pass out via the oviduct, reproduction is hampered, and if there is total blockage, the snail dies. In both examples, the endocrine disruptors interfere with fertility and disrupt reproduction of the species.
Page Ref: 108
67)
Hormones are chemicals that are released into the blood and travel all over the body where they can have effects on their target cells. Discuss the mechanisms that allow only the target cells to respond and how target cells may have very different responses to the same hormone.
Answer:
In order for a target cell to respond to a hormone, it must have a receptor. The receptor will have a ligand-binding domain that is specific for certain ligands. (Not all ligands can bind to all receptors.) Thus, only certain hormones will be able to affect a cell. Each receptor also has a functional domain that interacts with the intracellular compartments. Two receptors could have the same ligand-binding domain, which allows them to bind to the same hormone, but have different functional domains. Thus, when the ligand binds the receptor, it will generate the effect associated with its functional domain.
Page Ref: 112-114
68)
Once a ligand has bound to a receptor, it will continue to generate its response. In order to stop that response, the ligand must be removed or inactivated in some way. Describe the different ways this may be accomplished, along with features of each method.
Answer:
One way in which ligands will leave their receptor is if the surrounding concentration decreases. This can be achieved by having the ligand leave via the blood where it can be degraded by the liver or kidneys, or by having adjacent cells take up excess ligand. If using the blood, this process will take a little longer. Using adjacent cells is certainly more rapid, but these cells may not always be located in close enough proximity. A third method for reducing local concentrations uses enzymes to digest any free ligand. Again, this is more rapid, but does require the enzymes to be present. Alternatively, the whole receptor-ligand complex can be endocytosed and digested within the cell. It is also possible to inactivate the functional domains of the receptor so that the effects of the ligand are no longer occurring intracellularly.
Page Ref: 115-118
69)
There is a tremendous variety of signal transduction pathways with a wide range of functions. However, all these pathways have some things in common. Discuss some of these common features.
Answer:
All signal transduction pathways start with a ligand, the chemical message, binding to a receptor. The receptor will change its conformation because the weak bonds that hold the protein in one conformation change when the ligand binds. This leads to the activation of an intracellular substance, which may activate another substance. This cascade of events allows a very small original signal to amplify the signal in its target cell.
Page Ref: 118-119
70) Define hormones and briefly summarize their function. Provide an example to support your answer.
Answer: Hormones are chemical substances or signaling molecules of the endocrine system that regulate the activity of cells. Hormones regulate many physiological processes, such as reproduction, development, growth, metabolism, and behavior. Endocrine tissues produce hormones. Before a substance can be classified as a hormone, it must accomplish four functions: 1) have a signaling function, 2) be transported via the circulatory system, 3) bind to a specific receptor, and 4) exert its effect at low concentrations. One hormone may influence several physiological responses. For example, somatostatin hormones regulate blood glucose and other nutrients, and also affect growth and metabolism. Interaction between hormones plays an important role in physiological regulation. In glucose metabolism, we see that insulin and glucagon both regulate blood glucose levels. Hormone levels in the blood are tightly regulated and the regulation is accomplished via feedback loops.
Page Ref: 130-133
71)
Compare and contrast positive and negative feedback loops.
Answer:
All feedback loops have some similar parts. A sensor or receptor senses the environment. This information is relayed to an integrating center, which compares the sensed information to the set point. The response of the integrating center will be sent to an effector, which will carry out the response of the system. This is where the similarities end. In a negative feedback loop, the effector works to bring variables back into the set point range. In a positive feedback loop, any changes will be amplified because the effector will work to ensure that the variables will continue to move away from the set point.
Page Ref: 133-135
72))
Under stressful or dangerous situations, organisms enter into the flight-or-fight response. This response has both neural and endocrine components. Discuss the functions of each component and how they interact with each other.
Answer:
The sympathetic division of the nervous system becomes very active in response to stressful or startling stimuli. While the animals motor neurons are stimulating skeletal muscles to contract in running away or fighting, the sympathetic drive is increasing heart rate and breathing rate. Additionally, blood vessels going toward skeletal muscles will dilate to ensure an adequate supply of oxygen and nutrients. At the same time, the sympathetic drive stimulates the adrenal medulla to release epinephrine into the bloodstream. This will also increase heart and respiratory rates. The nervous system also stimulates glucagon release and inhibits insulin release to maintain high plasma levels of glucose. The high plasma glucose levels will be enhanced by the release of glucocorticoids from the adrenal cortex.
Page Ref: 140-143
Chapter 13 Ion and Water Balance
1) How do iguanas maintain water and ion balance?
Answer: B
Page Ref: 543
2)
Most animals rely on tissues such as the gills, skin, and kidney to regulate three homeostatic processes. Which of the following is NOT one of those processes?
osmotic regulation
ionic regulation
nitrogen excretion
endocrine balance
Answer:
D
Page Ref: 543
3)
Ammonia is the end product of __________ catabolism.
protein
carbohydrate
lipid
nitrogen
Answer:
A
Page Ref: 543
4)
Osmosis is
the energetically favorable movement of water across a semipermeable membrane, from an area with a high activity of water to an area with low activity of water.
the energetically costly movement of water across a semipermeable membrane, from an area with a high activity of water to an area with low activity of water.
the energetically favorable movement of solute across a semipermeable membrane from an area with a low activity of water to an area with high activity of water.
the energetically favorable movement of water across a semipermeable membrane from an area with a low activity of water to an area with high activity of water.
Answer:
A
Page Ref: 543
5)
All animals require water, and it may be provided in many forms. Which of the following is NEVER a source of water for an animal?
seawater
dietary water
products of hydrolysis
products of oxidative phosphorylation
Answer:
C
Page Ref: 546
6)
Where do humans obtain most of their water?
drinking water
water trapped in solid food
metabolic water
condensation reactions
Answer:
A
Page Ref: 547
7)
Perturbing solutes include all of the following EXCEPT
Na+.
K+.
charged amino acids.
trehalose.
Answer:
D
Page Ref: 547
8)
Compatible solutes
disrupt macromolecular function.
do not disrupt macromolecular function, as long as the concentration is low.
do not disrupt macromolecular function, even at high concentration.
do not disrupt macromolecular function, as long as there are counteracting solutes present.
Answer:
C
Page Ref: 547
9)
The cytoplasm of most animals is dominated by the same ions. Which of the following is NOT one of those ions?
K+
Cl-
Na+
SO4-
Answer:
C
Page Ref: 548
10)
Which of the following features of the stratum corneum is incorrect?
It is composed of differentiated epithelial cells.
Its purpose is to reduce water loss.
The tissue is dead and unresponsive to physical changes.
It is heavily keratinized.
Answer:
C
Page Ref: 551-552
11)
The main component of insect chitin is
polysaccharide.
protein.
lipid.
&n
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