Animal Form and Function Amplifire
Ligaments connect ________ to ________.
Ligaments connect bone to bone. Tendons connect bone to muscle.
Which of the following is a benefit of multicellularity compared to organisms consisting of just one cell?
A benefit of multicellularity compared to organisms consisting of just one cell is that cells can specialize. Multicellularity allows the cells of an organism to develop different, or specialized, functions such as processing certain nutrients, eliminating waste, sensing the environment, etc. This is distinct from the capabilities of a single-celled organism, where one cell performs all metabolic functions. Single-celled organisms cannot grow to larger sizes than multicellular organisms because of the need to maximize the surface area-to-volume ratio. Only multicellular organisms form tissues. Although unicellular organisms may be less likely to experience breakdown or disease than multicellular organisms, this is a minor advantage compared to their other disadvantages.
A neuron receives nerve impulses from other neurons via its _________ and __________.
A neuron receives nerve impulses from other neurons via its cell body and dendrites. Nervous tissue functions in the receipt, processing, and transmission of information. Nervous tissue contains neurons, or nerve cells, which transmit nerve impulses as well as support cells called glial cells, or simply glia. In many animals, a concentration of nervous tissue forms a brain, an information-processing center. Neurons are the basic units of the nervous system. Neurons transmit impulses to other neurons, to muscles, or to other cells via extensions called axons, which are often bundled together into nerves.
A physiological state of decreased activity and metabolism that is an adaptation enabling animals to save energy while avoiding difficult and dangerous conditions is known as _________.
A physiological state of decreased activity and metabolism that is an adaptation enabling animals to save energy while avoiding difficult and dangerous conditions is known as torpor. Despite their many adaptations for maintaining homeostasis, animals may encounter conditions that severely challenge their abilities to balance their heat, energy, and materials budgets. For example, at certain times of the day or year, their surroundings may be extremely hot or cold, or food may be unavailable. Many small mammals and birds exhibit a daily torpor that seems to be adapted to feeding patterns. For instance, some bats feed at night and go into torpor in daylight. Chickadees and hummingbirds feed during the day and often go into torpor on cold nights: The body temperature of chickadees drops as much as 10°C (18°F) at night, and the temperature of hummingbirds can fall 25°C (45°F) or more. All endotherms that exhibit daily torpor are relatively small; when active, they have high metabolic rates and thus very high rates of energy consumption. Hibernation is long-term torpor. Ectothermy is a characteristic of organisms in which their body temperature is directly related to the temperature in the environment. In homeothermy, an organism maintains its body temperature using internal mechanisms. Homeostasis is the balance of internal conditions in organisms.
Which of the following mammals would you expect to have the highest basal metabolic rate (BMR)?
A shrew has the highest basal metabolic rate (BMR). Animals must maintain a minimum metabolic rate for basic functions such as cell maintenance, breathing, and heartbeat. Researchers measure this minimum metabolic rate differently for endotherms and ectotherms. The minimum metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing stress is called the basal metabolic rate (BMR). BMR is measured under a "comfortable" temperature range—a range that requires no generation or shedding of heat above the minimum. The relationship between metabolic rate and size profoundly affects energy consumption by body cells and tissues. The energy it takes to maintain each gram of body mass is inversely related to body size. Each gram of a mouse, for instance, requires about 20 times as many calories as does a gram of an elephant even though the whole elephant uses far more calories than the whole mouse does. The smaller animal's higher metabolic rate per gram demands a higher rate of oxygen delivery. To meet this demand, the smaller animal must have a higher breathing rate, blood volume (relative to its size), and heart rate.
Which of the following lists of animal structures is ordered from smallest to largest?
Animal structures are organized in a hierarchical fashion from cell, tissue, organ, to organ system. Cells form a working animal body because of their emergent properties, which arise from successive levels of structural and functional organization. Cells are organized into tissues, groups of cells with a similar appearance and a common function. Different types of tissues are further organized into functional units called organs. (The simplest animals, such as sponges, lack organs or even true tissues.) Groups of organs that work together, providing an additional level of organization and coordination, make up an organ system.
During a fever, the __________ readjusts the set point of the body to a __________ temperature.
During a fever, the hypothalamus readjusts the set point of the body to a higher temperature. The main "thermostat" in the body is the hypothalamus, a group of neurons in the brain that activate physiological mechanisms that control heat loss or heat retention. During a fever, the hypothalamus adjusts the set point of the body to a higher level so that the body "thinks" that a higher temperature is normal.
Which of the following statements correctly describes a difference between hormone signaling and neuron signaling?
Hormone signals travel throughout the body, but neuron signals travel to specific locations. In the endocrine system, signaling molecules released into the bloodstream by endocrine cells are carried to all locations in the body. In the nervous system, neurons transmit signals along dedicated routes that connect specific locations of the body. In each system, the type of pathway used is the same regardless of whether the signal's ultimate target is at the other end of the body or just a few cell diameters away. The signaling molecules broadcast throughout the body by the endocrine system are called hormones. Different hormones cause different and distinct effects, and only those cells that can receive a particular hormone respond. In the nervous system, signals called nerve impulses travel to specific target cells along communication lines consisting mainly of axons. Nerve impulses can cause a response in other neurons, in muscle cells, and in cells and glands that produce secretions. Unlike the endocrine system, the nervous system conveys information by the particular pathway the signal takes. For example, a person can distinguish among different musical notes because within the ear, each note's frequency activates neurons that connect to slightly different regions of the brain. Because the two major communication systems of the body differ in signal type, transmission, speed, and duration, it is not surprising that they are adapted to perform different functions. The endocrine system is especially well adapted for coordinating gradual changes that affect the entire body, such as growth, development, reproduction, metabolic processes, and digestion. The nervous system is well suited for directing immediate and rapid responses to the environment, such as reflexes and other rapid movements. Hormone signals travel throughout the body, but neuron signals travel to specific locations. The neural response is limited to those cells that are connected by specialized junctions, whereas the hormone response is limited to those cells that have specific receptors. Endocrine cells secrete hormones as signals, and neuron cells transmit signals via axons. Neural signaling is rapid, and hormone signaling is much slower.
Humid weather makes you feel warmer because humid air, which is saturated with water molecules, __________.
Humid weather makes you feel warmer because humid air, which is saturated with water molecules, interferes with heat loss by evaporation. In humid weather, the concentration of water vapor in the air is high, and so the rate of evaporation from skin is slowed. Because evaporation cools the skin, a slower rate means less heat loss, causing you to feel warmer in higher humidity. Countercurrent heat exchange occurs in the blood vessels and involves conduction. Humidity does not affect the rate of metabolic heat production, nor does it interfere with heat loss due to conduction, which involves the direct transfer of heat from one object to another. High humidity is not always associated with higher temperatures.
When a person's body temperature increases, sweating helps bring the temperature down. This is an example of __________.
In this situation, negative feedback is the cause for body temperature to decrease. The steady body temperature of a river otter and the stable concentration of solutes in a freshwater bass are examples of homeostasis, which means "steady state" and refers to the maintenance of internal balance. In achieving homeostasis, animals maintain a relatively constant internal environment even when the external environment changes significantly. Homeostasis in animals relies largely on negative feedback, a control mechanism that reduces, or "damps," the stimulus. For example, when you exercise vigorously, you produce heat, which increases your body temperature. Your nervous system detects this increase and triggers sweating. As you sweat, the evaporation of moisture from your skin cools your body, helping return your body temperature to its set point and eliminating the stimulus. Positive feedback is a control mechanism that amplifies rather than reduces the stimulus. Hormone signaling may be involved in negative feedback, but it is not involved in the regulation of body temperature. A stimulus is a signal to which the body responds. In ectothermy, an organism's body temperature depends on the environment.
Interstitial fluid is __________.
Interstitial fluid is the fluid that fills the spaces between cells of vertebrates. The word interstitial means "stand between" in Latin, and this gives you a good hint as to what this fluid is. Interstitial fluid is the fluid that fills the spaces between cells in large animals such as vertebrates. This is where the exchange of nutrients, gases, waste, and other materials takes place. Blood is the liquid organ that is found only in the circulatory system. Many fluids inside the body, such as saliva, are restricted only to the organs that produce them. Similarly, fluids in compartments in the body, such as blood, food in the process of being digested, and urine, are confined to one compartment only. Beware of answers as general as "any place beneath the skin"—they will almost always be wrong!
__________ feedback most directly maintains homeostasis because it __________.
Negative feedback most directly maintains homeostasis because it tends to keep a system at a desirable "set point". Negative feedback maintains homeostasis by keeping a system at a desirable "set point." This type of feedback ensures that a change in the variable being monitored will trigger the control mechanism, which then counteracts further changes in the same direction. It does not accentuate fluctuations and keep the system from reaching equilibrium: This is the opposite of homeostasis. Positive, not negative, feedback, magnifies deviations from the "set point" and is not generally important in homeostasis.
Which of the following characteristics is likely to be found in larger versus smaller animals?
Larger animals are more likely than smaller animals to have a highly branched respiratory system. Animals must exchange nutrients, waste products, and gases with their environment, which imposes an additional limitation on body plans. Exchange occurs as substances dissolved in an aqueous solution move across the plasma membrane of each cell. A single-celled organism has a large enough membrane surface area in contact with its environment to be able to carry out all necessary exchange. In contrast, an animal is composed of many cells, each with its own plasma membrane across which exchange must occur. The rate of exchange is proportional to the membrane surface area involved in the exchange, whereas the amount of material that must be exchanged is proportional to body volume. A multicellular organism therefore survives only if every cell has access to a suitable aqueous environment, either inside or outside the animal's body. For example, in whales and most other animals, the evolutionary adaptations that enable sufficient exchange with the environment are specialized surfaces that are extensively branched or folded. In almost all cases, these exchange surfaces lie within the body, an arrangement that protects their delicate tissues from abrasion or dehydration and allows for streamlined body contours. The branching or folding greatly increases surface area: In humans, the internal exchange surfaces for digestion, respiration, and circulation each have an area more than 25 times that of the skin.
Microscopic analysis of an unknown tissue sample reveals the presence of chondrocytes, indicating that the sample was probably taken from __________ tissue.
Microscopic analysis of an unknown tissue sample reveals the presence of chondrocytes, indicating that the sample was probably taken from cartilage tissue. Chondrocytes are the basic cells of cartilage, a type of connective tissue, and the correct answer. Loose connective tissue is the most widespread type of connective tissue: its principal cell is the fibroblast. Stratified columnar epithelium is characteristic of epithelia, a different tissue type from connective tissue. Bone does not contain chondrocytes. Adipose tissue is a type of connective tissue that stores fat in adipose cells; it does not contain cartilage.
Most cells are microscopic because at this small size, __________.
Most cells are microscopic because at this small size, the ratio of surface area to cell volume is maximized. Cells are microscopic because their small size maximizes the ratio of surface area to cell volume. The cell surface area is very important because this is the location where materials—nutrients, waste, other factors—are exchanged with the environment across the cell membrane. Minimizing the amount of plasma membrane relative to the volume of a larger, more stable cytoplasm is the opposite of what the cell needs. Smaller cells may require fewer nutrients, but this is not the reason cells are small—it is to maximize the surface area/volume ratio. A smaller number of larger cells would be a more efficient organization for an organ than a larger number of small cells. The ease with which some small organisms evade detection by predators is the result of their smaller size, not the cause of the smaller size.
Myosin and actin are __________.
Myosin and actin are proteins that play a major role in muscle contraction. Myosin and actin are the most important proteins responsible for contraction in all muscle types. They are proteins, not types of muscle. Intercalated disks do not contain actin and myosin: They are structures specialized for electrical conduction among muscle cells in the heart. Myosin and actin are not part of a negative feedback loop.
Which of the six major types of connective tissue has a rigid matrix that contains collagen and calcium salts?
Of the six major types of connective tissue, bone has a rigid matrix that contains collagen and calcium salts. A helpful term in this question is rigid. As you know, bone is rigid: it forms the skeleton. Bone is a mineralized connective tissue whose matrix contains collagen along with calcium, magnesium, and phosphate ions. Adipose tissue has relatively little matrix, and loose connective tissue has loosely woven—not rigid—fibers that may be collagenous, reticular, or elastic. Cartilage contains collagen fibers and a rubbery, not rigid, matrix made of proteins and carbohydrates. Fibrous connective tissue contains densely arranged collagen fibers, but no calcium.
An organism that generates body heat by means of its own metabolism is _________, and an organism that gains body heat from external sources is ________.
Organisms that generate their own body heat are endothermic, and organisms that gain body heat from external sources are ectothermic. Thermoregulation is the process by which animals maintain their body temperature within a normal range. Heat for thermoregulation can come from either internal metabolism or the external environment. Humans and other mammals, as well as birds, are endothermic, meaning that they are warmed mostly by heat that is generated by metabolism. A few nonavian reptiles, some fishes, and many insect species are also mainly endothermic. In contrast, many nonavian reptiles and fishes, amphibians, and most invertebrates are ectothermic, meaning that they gain most of their heat from external sources. Endothermy and ectothermy are not mutually exclusive, however. For example, a bird is mainly endothermic, but it may warm itself in the sun on a cold morning, much as an ectothermic lizard does. Animals can have either a variable or a constant body temperature. An animal whose body temperature varies depending on its environment is called a poikilotherm (from the Greek poikilos, "varied"). In contrast, a homeotherm has a relatively constant body temperature. For example, the largemouth bass is a poikilotherm, and the river otter is a homeotherm. Organisms that generate their own body heat are endothermic, and organisms that gain body heat from external sources are ectothermic. A conformer allows its internal condition to change with external changes, whereas a regulator uses internal mechanisms to initiate internal changes. Body temperature in a poikilotherm varies with the environment, whereas body temperature in a homeotherm is controlled internally.
Which of the following pairs of connective tissue and its function is correctly matched?
Tendons attach muscles to bones. Connective tissue, consisting of a sparse population of cells scattered throughout an extracellular matrix, holds many tissues and organs together and in place. The matrix generally consists of a web of fibers embedded in a liquid, jellylike, or solid foundation. Within the matrix are numerous cells called fibroblasts, which secrete fiber proteins, and macrophages, which engulf foreign particles and any cell debris from phagocytosis. Connective tissue fibers are of three kinds: Collagenous fibers provide strength and flexibility, reticular fibers join connective tissue to adjacent tissues, and elastic fibers make tissues elastic. Fibrous connective tissue is dense with collagenous fibers and is found in tendons, which attach muscles to bones, and in ligaments, which connect bones at joints. Tendons attach muscles to bones. Ligaments connect bones at joints. Bone supports and protects the body. Adipose tissue pads and protects the body.
Which of the following organ systems in mammals is mismatched with its function?
The circulatory system is not involved in the coordination of body activities. The circulatory system of mammals includes the heart, blood vessels, and blood. Its main function is to distribute nutrients internally throughout the body. The endocrine system coordinates body activities. The digestive system processes food. The nervous system coordinates body activities. The muscular system is involved in locomotion and other movements. The excretory system is responsible for the disposal of metabolic wastes
Which of the following systems is correctly paired with one of its parts?
The correct pairing is endocrine system; thyroid gland. This gland influences metabolism in almost every cell type in the animal's body. The excretory system disposes of metabolic waste and regulates the osmotic balance of the blood via the kidneys, ureters, urinary bladder, and urethra. The circulatory system moves blood throughout the body using the heart and blood vessels. The lung belongs to the respiratory system, which performs gas exchange with the environment. The integumentary system (skin, hair, nails, certain glands) protects the organism against the environment.
The main function(s) of connective tissues in the body is/are _________.
The main functions of connective tissues are to hold tissues and organs in place and to join adjacent tissues together. Connective tissue, consisting of a sparse population of cells scattered throughout an extracellular matrix, holds many tissues and organs together and in place. The matrix generally consists of a web of fibers embedded in a liquid, jellylike, or solid foundation. Within the matrix are numerous cells called fibroblasts, which secrete fiber proteins, and macrophages, which engulf foreign particles and any cell debris from phagocytosis. Connective tissue fibers are of three kinds: Collagenous fibers provide strength and flexibility, reticular fibers join connective tissue to adjacent tissues, and elastic fibers make tissues elastic. If you pinch a fold of tissue on the back of your hand, the collagenous and reticular fibers will prevent the skin from being pulled too far from the bone, whereas the elastic fibers will restore the skin to its original shape when you release your grip. Different combinations of fibers and foundation form the major types of connective tissue. Epithelial tissues typically secrete molecules into the bloodstream. Epithelial tissues typically provide a surface for absorption of nutrients. Muscle tissues typically provide for locomotion and movements.
In blood, the matrix component is ________, and the cellular component contains _________.
The matrix of blood is plasma, and the cellular component contains red and white blood cells. Blood's extracellular matrix, called plasma, consists of water, salts, and dissolved proteins. Suspended in plasma are erythrocytes (red blood cells), leukocytes (white blood cells), and cell fragments called platelets. Red cells carry oxygen, white cells function in defense, and platelets aid in blood clotting. The matrix of blood is the plasma, and the cellular component contains red and white blood cells. Collagen and fibroblasts are found in loose and fibrous connective tissues. Collagen and chondrocytes are found in cartilage. Bone consists of a mineralized matrix and osteoblasts.
The __________ system and the __________ system work together to coordinate and control the bodies of most animals.
The nervous system and the endocrine system work together to coordinate and control the bodies of most animals. The most important term in this question is control; all of the systems listed are essential for animals' survival, but you must name the systems that control the other systems—the "bosses", in effect. The nervous and endocrine systems work together to control most of the physiological processes in animals. The circulatory system pumps blood throughout the body, while the digestive system extracts and absorbs nutrients from food, and processes waste. The nervous system coordinates physiological activities, processes information, detects and formulates responses to stimuli, and controls movement. The respiratory system manages gas exchange (oxygen uptake, carbon dioxide output). The immune system controls the body's response to infection and cancer.