When air temperature exceeds their body temperature, jackrabbits living in hot, arid lands will
constrict the blood vessels in their large ears.
Which choice best describes a reasonable evolutionary mechanism for animal structures becoming better suited to specific functions?
Animals with mutations that give rise to effective structures will become more abundant.
Evolutionary adaptations that help diverse animals exchange matter with the environment include
external respiratory surface, small size, and two-layered body.
Similar fusiform body shapes are seen in sharks, penguins, and aquatic mammals because
the laws of physics constrain the shapes that are possible for aquatic animals that swim very fast.
Regarding the evolution of specialized animal structures,
short-term adjustments to environmental changes are often mediated by physiological organ systems.
All animals, whether large or small, have
all of their living cells surrounded by an aqueous medium.
To increase the effectiveness of exchange surfaces in the lungs and in the intestines, evolutionary pressures have
increased the surface area available for exchange.
A specialized function shared by the many cells lining the lungs and the lumen of the gut is
increased exchange surface provided by their membranes.
Multicellular organisms must keep their cells awash in an ʺinternal pondʺ because
cells need an aqueous medium for the exchange of nutrients, gases, and wastes.
Blood is best classified as connective tissue because
its cells can be separated from each other by an extracellular matrix.
An example of a properly functioning homeostatic control system is seen when
the kidneys excrete salt into the urine when dietary salt levels rise.
An example of effectorsʹ roles in homeostatic responses is observable when
an increase in body temperature results from shivering.
Positive feedback has occurred when
a nursing infantʹs sucking increases the secretion of a milk-releasing hormone in the mother.
Positive feedback differs from negative feedback in that
the effectorʹs response in positive feedback is in the same direction as the initiating stimulus rather than opposite to it.
To prepare flight muscles for use on a cool morning, hawkmouth moths
rapidly contract and relax these muscles to generate metabolic warmth.
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.
An ectothermic organism that has few or no options when it comes to its behavioral ability to adjust its body temperature is a
sea star, a marine invertebrate.
An overheated and sick dog has an impaired thermoregulatory response if it
increases its body temperature to match the environmental temperature.
In mammals this response is known as fever, but it is known to raise body temperature in other bacterially infected animals, including lizards, fishes, and cockroaches:
a change in thermostat ʺset-pointʺ
What does the difference in temperature between arteries and veins in the gooseʹs legs indicate?
Minimizing the temperature difference between the feet and the abdomen means the goose will lose less
Near the gooseʹs abdomen, the consequence of this arrangement of the arterial and venous blood vessels is that
the temperature difference between the vessels is minimized by countercurrent exchange.
Seasonal changes in snake activity are explained by which statement?
The snake is more active in summer because it can gain body heat by conduction.
The best time to measure an animalʹs basal metabolic rate is when the animal
is resting and has not eaten its first meal of the day.
Standard metabolic rate (SMR) and basal metabolic rate (BMR)
are both measured in animals in a resting and fasting state.
For an adult human female, the metabolic ʺcostsʺ of pregnancy and lactation are
5—8% more than when she was non-pregnant.
Among these choices, the least reliable indicator of an animalʹs metabolic rate is the amount of
water consumed in one day.
Deer mice in warm climates and penguins in cold climates differ in their energy budgets in that
deer mice use a greater proportion of their metabolic energy to maintain body temperature.
During its months-long hibernation, the body temperature of a ground squirrel
varies between 5 and 37°C, depending on the frequency of arousals from hibernation.
For a non-hibernating squirrel, the daily expenditure of metabolic energy is
always greater than the basal metabolic rate (BMR).
Metabolism of specialized brown fat depots in certain animals is substantially increased during