Chapter 40
Organisms maintain dynamic homeostasis (internal balance) 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 ground squirrels hypothalamus detects changes in environmental temperatures and responds by activating or suppressing metabolic heat production.
Which statement about endotherms and ectotherms is correct?
Ectotherms are more abundant and diverse than endotherms.
How do endotherms and ectotherms differ?
Endotherms and ectotherms differ in the means by which they regulate their body temperature.
Which principle of heat exchange is the most important explanation for why birds look larger in colder weather because they fluff their feathers?
Fluffing creates a pocket of air near the bird that acts as insulation.
An elephant and a mouse are running in full sunlight, and both overheat by the same amount above their normal body temperatures. When they move into the shade and rest, which animal will cool down faster?
The mouse will because it has the higher surface-area-to-volume ratio.
Which of the following primarily involves heat transfer by convection?
You roll down the car window to allow the cool breeze to blow through.
Which of the following animals most likely uses the largest percentage of its energy budget for homeostatic regulation?
a bird living year round in a desert
In a physiological system operating with positive feedback, ____
a change in a variable will amplify rather than reverse the change
Most land-dwelling invertebrates and all of the amphibians _____.
are ectothermic organisms with variable body temperatures
Standard metabolic rate (SMR) and basal metabolic rate (BMR) are _____.
both measured in animals in a resting and fasting state
Most types of communication between cells utilize _____.
chemical or electrical signals
The body tissue that consists largely of material located outside of cells is ____
connective tissue
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.
elephant; mouse
Much of the coordination of vertebrate body functions via chemical signals is accomplished by the _____.
endocrine system
Bats and hummingbirds are examples of _____.
endotherms that are also poikilotherms
Negative feedback is a method of homeostatic control that _____.
ensures that conditions in an organism do not vary too much above or below their set points
There are advantages and disadvantages to adaptations. Animals that are endothermic are likely to be at the greatest disadvantage in _____.
environments with variable and limited food sources
Most of the exchange surfaces of multicellular animals are lined with _____.
epithelial tissue
Sweating allows a person to lose heat through the process of _____.
evaporation
Choose the list that correctly ranks metabolic rates per gram of body mass, from lowest to highest.
fish, dog, mouse
The temperature-regulating center of vertebrate animals is located in the _____.
hypothalamus
All types of muscle tissue have _____.
interactions between actin and myosin
In a cool environment, an ectotherm is more likely to survive an extended period of food deprivation than would an equally sized endotherm because the ectotherm _____.
invests little energy in temperature regulation
Homeostasis is the _____.
maintenance of a relatively constant and optimal internal environment
Snake behavior in Wisconsin changes throughout the year. For example, a snake is _____.
more active in summer because it can gain body heat by conduction
When the body's blood glucose level rises, the pancreas secretes insulin and, as a result, the blood glucose level declines. When the blood glucose level is low, the pancreas secretes glucagon and, as a result, the blood glucose level rises. Such regulation of the blood glucose level is the result of _____.
negative feedback
The four major categories of tissues are _____.
nervous, epithelial, connective, and muscle
The metabolic breakdown of specialized brown fat depots in certain animals is substantially increased during _____.
nonshivering thermogenesis
Once labor begins in childbirth, contractions increase in intensity and frequency, causing more contractions to occur until delivery. The increasing labor contractions of childbirth are an example of which type of regulation?
positive feedback
A countercurrent heat exchanger enables an animal to _____
reduce the loss of body heat to the environment
Connective tissues typically have _____.
relatively few cells and a large amount of extracellular matrix
A moth preparing for flight on a cold morning may warm its flight muscles via _____.
shivering thermogenesis
Food moves along the digestive tract as the result of contractions by _____.
smooth muscle
The type of muscle tissue surrounding the intestines and blood vessels is _____.
smooth muscle
Positive feedback differs from negative feedback in that _____.
the positive feedback's effector responses are in the same direction as the initiating stimulus rather than opposite of it
Metabolic rate is _____.
the total amount of energy an animal uses in a unit of time
Hummingbirds are small birds that require a regular food supply. When hummingbirds are faced with a situation that decreases their food supply, such as a storm, which of the following adaptations would be most useful for the bird to survive such an unpredictable and short-term absence of food resources?
torpor
Which of the following would increase the rate of heat exchange between an animal and its environment?
wind blowing across the body surface
