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When the temperature of the outside air exceeds their internal body temperature, jackrabbits living in hot, arid lands will
constrict the blood vessels in their large ears to reduce transfer of external heat to the blood in their ears.
If thermoregulation is considered to be a secondary function of the large ears of jackrabbits, then the primary function of the ears is
to detect predators by using the large size and flexible positioning of the external ears to channel sound waves into the ear canal.
Which choice best describes a reasonable mechanism for animal structures becoming better suited over evolutionary time to specific functions?
Animals with mutations that give rise to effective structures will become more abundant.
Penguins, seals, and tuna have body forms that permit rapid swimming, because
the shape is a convergent evolutionary solution to the need to reduce drag while swimming.
Evolutionary adaptations that help diverse animals directly exchange matter between cells and the environment include
an external respiratory surface, a small body size, and a two-cell-layered body.
The similar fusiform body shape of diverse animals, such as sharks, penguins, and aquatic mammals, has evolved because
this is the body shape that makes it possible for aquatic animals to swim rapidly.
The specialized structures of complex animals have evolved because
they permit adjustments to a wide range of environmental changes.
To increase the effectiveness of exchange surfaces lining the lungs and the intestines, evolutionary pressures have
increased the exchange surface area with folds and branches.
The specialized function shared by the cells that line the lungs and those that line the lumen of the gut is that both types of cells
provide abundant exchange surface.
Multicellular organisms must keep their cells awash in an "internal pond" because
an aqueous medium is needed for the cellular exchange of nutrients, gases, and wastes.
Of the following choices, the epithelium with the shortest diffusion distance is
simple squamous epithelium.
The absorptive epithelia in the gut are considered "polarized" because
The absorptive epithelia in the gut are considered "polarized" because
Connective tissues typically have
) relatively few cells and a large amount of extracellular matrix.
Blood is best classified as connective tissue because
its cells are separated from each other by an extracellular matrix.
Most types of communication between cells utilize
the release of chemical signals by the cell sending the message.
The body's automatic tendency to maintain a constant and optimal internal environment is termed
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 effectors' roles in homeostatic responses is observable when
an increase in body temperature results from involuntary shivering.
Positive feedback has occurred when
uterine contractions needed for the birthing process are expedited by the pressure of a moving baby in its mother's uterus.
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 to it.
To prepare flight muscles for use on a cool morning, hawkmouth moths
rapidly contract and relax these muscles to generate metabolic warmth.
In a survivably cold 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.
An example of an ectothermic organism that has few or no behavioral options when it comes to its ability to adjust its body temperature is a
sea star, a marine invertebrate.
An overheated and sick dog in a hot environment will have an impaired thermoregulatory response when its
body temperature increases to match the environmental temperature.
panting responses that are observed in overheated birds and mammals dissipates excess heat by
An example of an organism that has only behavioral controls over its body temperature is the
Most land-dwelling invertebrates and all of the amphibians
are ectothermic organisms with variable body temperatures.
) 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 the body's thermostat "set point"
Seasonal changes in snake activity are due to the fact that the snake
) is more active in summer because it can gain body heat by conduction.
Standard metabolic rate (SMR) and basal metabolic rate (BMR) are
both measured in animals in a resting and fasting state.
For adult human females, the metabolic "costs" of pregnancy and lactation are
5-8% more than when she was nonpregnant.
Among these choices, the least reliable indicator of an animal's metabolic rate is the amount of
water consumed in one day.
During its months-long hibernation in its burrow, the body temperature of a ground squirrel
varies between 5°C and 37°C, depending on the frequency of arousals from hibernation.
Catabolism of specialized brown fat depots in certain animals is substantially increased during
(Picture 6)The thin horizontal arrows in the figure above show that
the warmer arterial blood transfers heat to the cooler venous blood.
(Picture 6)Examine the figure above. Near a goose's abdomen, the countercurrent arrangement of the arterial and venous blood vessels causes
the temperature difference between the contents of the two sets of vessels to be minimized.
Imagine that you are a biologist who is attempting to get an accurate measure of an animal's basal metabolic rate. The best time to measure the metabolic rate is when the animal
is resting and has not eaten its first meal of the day.
Which of the following would increase the rate of heat exchange between an animal and its environment?
wind blowing across the body surface
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.
Compared with a smaller cell, a larger cell of the same shape has
less surface area per unit of volume.
An animal's inputs of energy and materials would exceed its outputs
if it is growing and increasing its mass.
You are studying a large tropical reptile that has a high and relatively stable body temperature. How would you determine whether this animal is an endotherm or an ectotherm?
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.
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