Nitrogenous Wastes Quiz and Flashcards

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Questions and Answers

What is the primary method of nitrogenous waste excretion in bony fishes, and how is it eliminated?

Ammonotelism; through the skin and gills as well as in urine.

What proportion of nitrogenous waste is composed of other nitrogen-containing compounds in humans?

14 percent

What is the energy requirement difference between ammonia production and urea synthesis?

Urea synthesis requires more energy than ammonia production.

What is the primary method of nitrogenous waste excretion in mammals, and what are the proportions of different compounds excreted?

Ureotelism; 82 percent urea, 2 percent each ammonia and uric acid. Signup and view all the answers

What is the advantage of ureotelism over ammonotelism?

Urea is less toxic than ammonia and can be concentrated in urine, thus conserving water. Signup and view all the answers

What is the term for excreting nitrogenous wastes primarily as uric acid?

Uricotelism Signup and view all the answers

What is the significance of a Q10 value of 1.0 in relation to the rate of a chemical reaction?

A Q10 of 1.0 means that the rate of the reaction stays the same. Signup and view all the answers

What is included in the standard metabolic rate (SMR) of an organism?

The SMR includes the costs of ventilating the lungs or gills, of pumping blood through the circulatory system, of transporting ions across membranes, and of all the other activities necessary to maintain the integrity of an organism. Signup and view all the answers

What is the effect of an increase in body temperature on the energy cost of living for an organism?

The energy cost of living increases with an increase in body temperature. Signup and view all the answers

If the Q10 of a reaction is 2, what would be the rate of the reaction at 20°C if it is 2 joules per minute at 10°C?

The rate would be 4 joules per minute at 20°C. Signup and view all the answers

What is the implication of an increase in energy use for an organism?

An increase in energy use translates to a corresponding increase in the amount of food the organism must eat. Signup and view all the answers

At what level of biological organization can Q10 be used to describe the effect of temperature on biological processes?

Q10 can be used to describe the effect of temperature on biological processes at all levels of biological organization, from whole animals down to molecules. Signup and view all the answers

What is the main limitation of using the terms poikilothermy and homeothermy to describe animal thermoregulation?

These terms cannot be applied to groups of animals and do not accurately describe the variability of body temperature. Signup and view all the answers

Why do most biologists prefer the terms ectothermy and endothermy over homeothermy and poikilothermy?

They prefer these terms because they refer to the sources of energy used in thermoregulation, not the variability of body temperature. Signup and view all the answers

What is the key difference between ectotherms and endotherms?

The key difference lies in the source of heat used to maintain body temperature, with ectotherms relying on external sources and endotherms relying on metabolic heat production. Signup and view all the answers

Provide an example of an ectothermic behavior.

Basking in the sun or resting on a warm rock to gain heat. Signup and view all the answers

What is the significance of the Greek roots 'ecto' and 'endo' in the terms ectotherm and endotherm?

The roots 'ecto' meaning 'outside' and 'endo' meaning 'inside' refer to the source of heat used in thermoregulation, with ectotherms using external heat and endotherms using internal metabolic heat. Signup and view all the answers

What is the main complication in using the terms homeotherm and poikilotherm, as highlighted by the example of mammals and fishes?

The complication arises because homeotherms can experience larger variations in body temperature than poikilotherms, making the terms difficult to use rigorously. Signup and view all the answers

How does the activity of the enzyme lactic dehydrogenase from a lungfish change with temperature?

The activity of the enzyme increases slowly from 25°C to 35°C, more steeply between 35°C and its maximum at 40°C, and declines rapidly between 40°C and 50°C. Signup and view all the answers

How do roadrunners regulate their body temperature, and what is the energetic benefit of this behavior?

Roadrunners bask in the sun and raise the feathers on their backs to expose black skin, allowing them to save 132 joules per hour by using solar energy instead of metabolism. Signup and view all the answers

How do female pythons regulate the temperature of their eggs, and what is the energetic cost of this behavior?

Female pythons coil around their eggs and produce heat by rhythmic contraction of their trunk muscles, increasing their metabolic rate by a factor of 20. Signup and view all the answers

What is an example of regional heterothermy in vertebrates, and what is its significance?

An example is the ability of female pythons to regulate the temperature of their eggs, highlighting the importance of considering regional variations in body temperature regulation. Signup and view all the answers

What does the Q10 value of 1.2 indicate about the temperature sensitivity of the enzyme lactic dehydrogenase?

The Q10 value of 1.2 indicates that the enzyme activity increases by a factor of 1.2 for every 10°C increase in temperature. Signup and view all the answers

What is the significance of studying the mechanisms of thermoregulation in vertebrates, and why must generalizations be made cautiously?

Studying thermoregulation mechanisms is important because it reveals the complexity and variability of temperature regulation strategies in vertebrates. Signup and view all the answers

What is the primary function of blubber in marine mammals, and how does it affect their behavior on land?

Blubber is an extremely effective insulator that helps marine mammals retain heat in cold water. However, it can lead to overheating if they engage in prolonged strenuous activity on land. Signup and view all the answers

How do countercurrent exchange systems in marine mammals' flippers contribute to heat retention or loss?

The cold venous blood returning from the flippers is heated by warm arterial blood flowing out from the core of the body, allowing marine mammals to retain heat or release it to the ocean as needed. Signup and view all the answers

What is the difference between the insulation mechanisms used by semiaquatic mammals and those used by fully marine mammals?

Semiaquatic mammals, such as otters and beavers, have water-repellent coats that require frequent grooming, whereas fully marine mammals, such as cetaceans and pinnipeds, use blubber as their primary insulator. Signup and view all the answers

Why do some seals risk death by overheating if they undertake prolonged strenuous activity on land?

Their blubber is so effective as an insulator that it can cause them to overheat if they do not have a way to release excess heat. Signup and view all the answers

What is the role of the flippers in the countercurrent exchange system of marine mammals?

The flippers act as a site for heat exchange, with cold venous blood returning from the flippers being heated by warm arterial blood flowing out from the core of the body. Signup and view all the answers

How do marine mammals regulate their body temperature in response to changes in their environment?

They use their countercurrent exchange systems to retain heat in the body or release it to the ocean as needed, allowing them to maintain a stable body temperature despite changes in their environment. Signup and view all the answers

Many terrestrial vertebrates and some aquatic vertebrates do have body temperatures substantially above the temperature of the surrounding ______.

air or water Signup and view all the answers

The rates of many biological processes are affected by ______.

temperature Signup and view all the answers

Fishes, amphibians, and reptiles were called ______.

poikilotherms Signup and view all the answers

Birds and mammals were ______.

homeotherms Signup and view all the answers

Air has both a lower heat capacity and a lower heat conductivity than ______.

water Signup and view all the answers

Poikilotherms were animals with variable ______ temperatures.

body Signup and view all the answers

Terrestrial ______ (like lizards and turtles) and endotherms (like birds and mammals) have activity temperatures between 30°C and 40°C.

ectotherms Signup and view all the answers

Roadrunners are predatory ______ living in the deserts of the southwestern United States and adjacent Mexico.

birds Signup and view all the answers

Endothermy and ______ are not mutually exclusive mechanisms of temperature regulation, and many animals use them in combination.

ectothermy Signup and view all the answers

On cold nights, roadrunners allow their body temperatures to fall from the normal level of 38°C or 39°C down to ______ or lower.

35°C Signup and view all the answers

Between 10°C and 20°C the rate ______ from 50 to 100, which is a Q10 of 2.0.

doubles Signup and view all the answers

The maximum swimming speed of a goldfish increases up to about ______ and then falls.

30°C Signup and view all the answers

A cube 10 centimeters on a side has a surface/volume ratio of 600 cm2/1000 cm3, which is ______ cm2/1 cm3.

0.6 Signup and view all the answers

Large animals have proportionally less ______ area for exchange in relation to the volume of their bodies than small animals do.

surface Signup and view all the answers

Bigger species exchange energy with the environment less rapidly than smaller species, merely because of the difference in ______ ratios.

surface/volume Signup and view all the answers

Gigantothermy is a form of thermoregulation where an animal's body temperature will be stable simply because it's so ______.

big Signup and view all the answers

Exchange between an animal and its environment occurs through its ______ surface.

body Signup and view all the answers

As an object gets larger, it has progressively less ______ area in relation to its volume.

surface Signup and view all the answers

The enormous ______ that lived in the Jurassic and Cretaceous periods would have had very stable body temperatures just because they were so large.

dinosaurs Signup and view all the answers

Even ______ (which are only one-twentieth the size of the largest dinosaurs) are big enough to feel the consequences of surface/volume ratio in body-temperature regulation.

elephants Signup and view all the answers

Leatherbacks (Dermochelys coriacea) are the largest living ______, reaching adult body masses of 850 kilograms or more.

turtles Signup and view all the answers

[Blank] can easily overheat when they are active.

Elephants Signup and view all the answers

Being big makes temperature regulation in ______ easier, as leatherback sea turtles dramatically illustrate.

water Signup and view all the answers

When ______ dump heat, they send large volumes of blood flowing through their ears and waving them to promote cooling.

elephants Signup and view all the answers

The Surface to Volume __________ of a cube decreases as the size of the cube increases.

Ratio Signup and view all the answers

As the length of the side of the cube is increased from 1 cm to 10 cm, the total surface area of the cube increases as the __________ of that length.

square Signup and view all the answers

Because volume increases more rapidly than surface area, the surface to volume __________ of the cube decreases as the size of the cube increases.

Ratio Signup and view all the answers

Functionally this means that as an object becomes larger, it has less surface area relative to its __________.

volume Signup and view all the answers

The rate of exchange with the environment __________ as the size of the cube increases.

decreases Signup and view all the answers

For example, if you take two cubes—one that is 1 cm on a side and the other 10 cm on a side—and then heat them to the same temperature and put them side by side on a table, the small cube will cool to room temperature __________ than the large cube.

faster Signup and view all the answers

Study Notes

Temperature Regulation in Animals

Terrestrial ectotherms (like lizards and turtles) and endotherms (like birds and mammals) have activity temperatures between 30°C and 40°C.
Endothermy and ectothermy are not mutually exclusive mechanisms of temperature regulation, and many animals use them in combination.
Birds and mammals are primarily endothermal, but some species make extensive use of external sources of heat.
Roadrunners, for example, allow their body temperatures to fall from 38°C or 39°C to 35°C or lower on cold nights, and then raise it back up in the morning using solar energy.

The Effect of Temperature on Organisms

The rate of most chemical reactions increases or decreases when the temperature changes.
The ratio of the rate at one temperature and the rate at a temperature 10°C higher is called Q10.
A Q10 of 1.0 means that the rate stays the same, a Q10 greater than 1 means the rate increases, and a Q10 less than 1.0 indicates the rate decreases.
Examples of the effect of temperature on organisms include:
- A hypothetical reaction for which the rate initially increases and then falls as temperature rises.
- The maximum swimming speed of a goldfish, which increases up to about 30°C and then falls.
- Spontaneous activity by a goldfish, which peaks at around 20°C and falls as the temperature increases.

Gigantothermy

Simply being big gives an animal some independence of external temperature because heat cannot flow rapidly into or out of a large body through its relatively small surface.
This is a form of thermoregulation called gigantothermy.
Examples of gigantothermy include:
- Large dinosaurs, which had very stable body temperatures due to their size.
- Elephants, which are big enough to feel the consequences of surface/volume ratio in body-temperature regulation.

Body Size and Surface/Volume Ratio

The surface/volume ratio of an animal changes with its size.
As an object becomes larger, it has less surface area relative to its volume.
This means that as an animal becomes larger, it has less surface area for exchange with the environment.
Examples of the effect of body size on surface/volume ratio include:
- A cube, which illustrates how the surface/volume ratio changes with size.
- A comparison of the surface/volume ratio of small and large animals.