1. Triglycerides are used to store energy for later use.
2. An animal produces metabolic waste energy in the form of heat.
3. An animal has insulation, which helps it maintain a constant body temperature.
4. An animal eats a large amount of high-fat foods to produce adipose tissue.

Ectotherms and endotherms have different strategies for generating and maintaining body heat. Explain why ectotherms are more dependent on the environment for body heat than endotherms and how endotherms are able to generate and maintain body temperature.

1. Ectotherms use external thermal heat whereas endotherms use metabolically generated heat to help regulate and maintain body temperatures.
2. Ectotherms use external heat to help regulate and maintain body temperatures whereas endotherms have constantly varying internal temperatures.
3. Ectotherms use metabolically generated heat to maintain a constant body temperature whereas endotherms use metabolically generated heat to regulate body temperature within a wider range.
4. Ectotherms use external thermal energy to help regulate and maintain body temperatures whereas endotherms maintain a constant body temperature.

1. During cold periods, pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes, while some plants make antifreeze proteins to prevent ice crystal formation in tissues.
2. Bacteria lack introns, while many eukaryotic genes contain many of these intervening sequences.
3. Carnivores have more teeth that are specialized for grinding food.
4. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

The body sizes of organisms vary and tends to be correlated with the region in which the organisms are found. Why do organisms at different latitudes tend to have different body sizes, and what is the relationship between heat loss and body size in an organism?

1. Temperature varies by latitude, and body size affects heat retention and loss. Smaller organisms lose heat at a slower rate than larger organisms, because they have a smaller surface area for their mass.
2. Temperature varies by latitude, and body size affects heat retention and loss. Smaller organisms lose heat at a faster rate than larger organisms, because they have a greater surface area for their mass.
3. Temperature varies by latitude, and body size affects heat retention and loss. Larger organisms lose heat at a faster rate than smaller organisms, because they have a greater surface area for their mass.
4. Temperature varies by latitude, and body size affects heat retention and loss. Smaller organisms lose heat at a faster rate than larger organisms, because they have a smaller surface area for their mass.

1. increase vasodilation
2. sweat
3. move into shade
4. increase metabolic rate

1. Colder temperatures causes ATP to degrade.
2. ATP is synthesized through cellular respiration, which provides body heat.
3. ATP synthesis is needed to provide more oxygen to the cells.
4. ATP is consumed by the cells to generate body heat.

1. Hummingbirds have a fast metabolic rate and a large surface area to volume ratio.
2. Hummingbirds are unable to lower their metabolic rate and body temperature to enter hibernation.
3. Hummingbirds migrate south for the winter.
4. Hummingbirds live a short life.

How does hibernation differ in small animals such as ground squirrels and larger animalssuch as bears?

1. Smaller animals can engage in torpor, while larger animals cannot.
2. Larger animals can engage in torpor, while smaller animals cannot.
3. Smaller animals cannot remain inactive throughout the entire winter, while larger animals can.
4. Larger animals cannot remain inactive throughout the entire winter, while smaller animals can.

Figure 24.25

What can you conclude from the data collected on five different animals as shown in the table above?

1. The time it takes for animals to change body temperature is directly related to body size.
2. The time it takes for animals to change their body temperature is indirectly related to their size.
3. Larger animals hibernate for longer periods of time.
4. Smaller animals hibernate for shorter periods of time.

Figure 24.26

What can you conclude from about the time it takes to cool down versus the time it takes to warm up?

1. Larger animals consume more energy to maintain their body temperatures.
2. Smaller animals can survive hibernation with less food reserves than larger animals.
3. Smaller animals require more time to alter their body temperature.
4. Larger animals require more time to alter their body temperature.

1. During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin.
2. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.
3. At high elevation, atmospheric oxygen is scarcer. In response to signals that oxygen is low, the brain decreases an individual’s rate of respiration to compensate for the difference.
4. A transcription factor binds to the regulating region of a gene, blocking the binding of another transcription factor required for expression.

Figure 24.27

Describe how blood calcium control is an example of a negative-feedback loop.

1. Cells in the parathyroid gland sense calcium decrease causing parathyroid hormone release and stimulating calcium absorption. Bone may also break down to release calcium.
2. Cells in the parathyroid gland sense calcium decrease causing calcitonin release and stimulating calcium absorption. Bone may also break down to release calcium.
3. Cells in the thyroid gland sense calcium decrease causing calcitonin release and stimulating calcium absorption. Bone may also break down to release calcium.
4. Cells in the parathyroid gland sense calcium increase causing parathyroid hormone release and stimulating calcium absorption. Bone may also break down to release calcium.

1. When a fetus pushes against the uterine wall, insulin is released by the brain to stimulate uterine contractions.
2. In the presence of decreased blood glucose levels, insulin is produced by the parathyroid to increase calcium absorption.
3. Insulin activation activates other clotting factors until a fibrin clot is produced.
4. Insulin is secreted by the pancreas in response to elevated blood glucose levels to remove glucose from the blood.

1. When blood sugar is low, glucose and ATP produce glycogen. Excess blood sugar stimulates the release of glucagon, which in turn stimulates glycogen release to increase blood glucose levels.
2. When there is excess blood sugar, excess glucose and ATP produce glucagon. A drop in blood glucose level stimulates the release of glycogen, which in turn stimulates glycogen release to increase blood glucose levels.
3. When there is excess blood sugar, the excess glucose and ATP produce glycogen. A drop in blood glucose level stimulates the release of glucagon, which in turn stimulates the release of glycogen to increase blood glucose levels.
4. When there is excess blood sugar, the excess glucose and ATP produce glycogen. A drop in blood glucose level stimulates the release of glucagon, which in turn releases more glucagon to increase blood glucose levels.

One process that is under the control of a negative-feedback loop is red blood cell production. These cells carry oxygen to all of the body cells, and remove some carbon dioxide. What would most likely happen if an individual had a sufficient number of red blood cells?

1. The individual would have increased red blood cell production.
2. The individual’s body would start destroying the red blood cells.
3. The individual’s body would cease production of new red blood cells.
4. The individual would produce the same amount of red blood cells.

1. Insulin injections allow transport and storage of glucose to increase blood glucose levels after consuming a large or high-glucose meal.
2. Insulin injections allow only storage of glucose to decrease blood glucose levels after consuming a large or high-glucose meal.
3. Insulin injections allow transport and storage of glucose to increase blood glucose levels before consuming a meal.
4. Insulin injections allow transport and storage of glucose to decrease blood glucose levels after consuming a large or high-glucose meal.

1. Oxytocin halts uterine contractions when the fetus pushes on the uterine wall.
2. Oxytocin maintains pain levels as the child is pushed through the birth canal.
3. Oxytocin stimulates uterine contractions when the fetus pushes on the uterine wall.
4. Oxytocin decreases pain levels as the child is pushed through the birth canal.

Birth is one of the few positive-feedback loops observed in humans and is essential for the proper delivery of babies. Describe how a baby pushing against a pregnant woman’s cervix stimulates a positive-feedback loop.

1. Stretching stimulates nerve impulses to be sent to the brain, which releases oxytocin from the pituitary, which in turn causes uterine contractions.
2. Stretching stimulates nerve impulses to be sent to the brain, which releases estrogen from the pituitary, which in turn causes uterine contractions.
3. Stretching stimulates nerve impulses to be sent to the brain, which releases oxytocin from the parathyroid gland, which in turn causes uterine contractions.
4. Stretching stimulates nerve impulses to be sent to the brain which releases progesterone from the pituitary, which in turn causes uterine contractions.

Negative-feedback mechanisms are far more prevalent in the human body than positive-feedback loops because they help regulate homeostasis. However, there are some instances of positive-feedback loops that can be observed in animals. Regulation of which of the following is an example of a positive-feedback loop?

1. When body temperature gets too high, signals are sent to reduce body temperature.
2. Increased blood glucose levels stimulate insulin production, which in turn sequesters glucose from the blood.
3. Decreased calcium levels stimulate increased calcium absorption.
4. Activation of one clotting factor stimulates production of other clotting factors until a fibrin clot is produced.

Both negative and positive-feedback loops are essential for maintaining proper body functions. Blood calcium and blood clotting are under the control of different feedback loops. Which of these processes is maintained by a positive-feedback loop and why?

1. Blood clotting is maintained by a positive-feedback loop, as clotting is amplified in response by increasing the amount of clotting factors when clotting factors are present.
2. Blood clotting is maintained by a positive-feedback loop, as clotting factors are maintained in a specific range and a positive loop helps return the conditions to the set point.
3. Blood calcium is maintained by a positive-feedback loop, as calcium levels are amplified in response by increasing the amount of calcium levels when calcium is present.
4. Blood calcium is maintained by a positive-feedback loop, as calcium levels are maintained in a specific range and a positive-feedback loop helps return the conditions to the set point.