Mastering Biology Chapter 32 HW #2

Select the correct statement describing feedback control in animals.

An animal may be a regulator for one environmental variable but a conformer for another.

Having a low-grade fever of 100° to 102°F is a common side effect of a bacterial infection. Which of the following statements provides the most reasonable explanation for why this could be beneficial?

An increase in body temperature could denature enzymes in heat-sensitive bacteria without denaturing the enzymes of the person with the infection.

Which of the following is generally true within the human body?

When a person is warm, blood flow near the skin and in the extremities increases.

Which of the following primarily involves heat transfer by convection?

You roll down the car window to allow the cool breeze to blow through.

You can estimate the contribution of each wedge in a pie chart by remembering that the entire circle represents 100%, half is 50%, and so on. What percent of the mouse's energy budget goes to basal metabolism?

about 25%

Which animal expends the most kilocalories per year on thermoregulation?

the penguin

Which of the following would increase the rate of heat exchange between an animal and its environment?

wind blowing across the body surface

Why does the reporter have a tube up his nose?

to accurately measure core temperature

The figure shows how urine concentration occurs in the nephron, the functional unit of the vertebrate kidney. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.

1. The kidney's ability to concentrate urine depends on the maintenance of an osmolarity gradient between the interstitial fluid of two structures: the cortex and the medulla. 2. This osmolarity gradient is maintained by both the passive transport and the active transport of NaCl. 3. The osmolarity gradient is also maintained by the passive transport of urea. 4. Water responds to the osmolarity gradient by moving from an area of lower solute concentration to an area of higher solute concentration--a process called osmosis. 5. Osmosis does not require energy. For this reason, osmosis is a form of passive transport. 6. The loss of water from the filtrate results in urine that is highly concentrated.

Which of the following statements about endocrine glands and the hormones they produce is true?

Aldosterone produced by the adrenal glands controls the reabsorption of sodium ions by the kidneys.

Select the correct statement about osmoregulation.

All osmoconformers are marine animals.

If you monitored energy allocation in an adult penguin for just a few months instead of an entire year, you might find the growth category to be a significant part of the pie chart. Given that adult penguins don't grow from year to year, how would you explain this finding?

At certain times, penguins store considerable energy as fat, putting on weight in the process.

Which of the following occurs when body temperature decreases below normal body temperature?

Blood vessels in the skin constrict to help prevent heat loss

Why does an enzyme cease to function when it has become denatured?

Denaturation changes the three-dimensional shape of the active site of the enzyme, preventing it from binding to the substrate.

Select the correct statement about feedback regulation in endocrine systems.

Some homeostatic control systems rely on pairs of negatively regulated hormone pathways, each counterbalancing the other.

The regions of the nephron through which filtrate flows are labeled in the figure below. Drag each statement to the appropriate bin depending on whether it applies to the descending limb of the loop of Henle, the ascending limb of the loop of Henle, or the collecting duct.

Descending Limb of the Loop of Henle - no energy required for transport - numerous aquaporins (water channels) but almost no ion channels - epithelium always permeable to water Ascending Limb of the Loop of Henle - no aquapoins (water channels) - passive transport of NaCl in the thin segment and active transport of NaCl in the thick segment Collecting Duct - hormones control permeability to water and transport of NaCl - active transport of NaCl associated with loss of water from filtrate

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 of the following is an accurate statement about thermoregulation?

Endotherms and ectotherms differ in their primary source of heat for thermoregulation

Which statement is true about enzymes in the human body?

Enzymes in the human body usually work best at normal body temperature.

The reporter is participating in a study within a room that is heated. Why is he also on a treadmill?

Exercising causes a faster increase in his core temperature.

The images below show two countercurrent heat exchangers in marine animals: in the flipper of a sea turtle (left) and in the abdomen of a dolphin (right). Which three of the following statements are consistent with the images?

In a dolphin, blood cools as it flows from the aorta to the testes. At a dolphin's testes, heat is transferred from (1) to (2). In a sea turtle's flippers, heat is transferred from (1) to (3).

Which of the following statements about the pituitary gland is false?

Neurosecretory cells produce hormones that are stored in the anterior pituitary.

Select the correct statement about osmolarity.

Osmolarity measures the moles of solute per liter of solution.

Both passive and active transport are used to move molecules into and out of cells, as shown in the figure. Identify the key differences between passive and active transport, and provide an example of each. Drag the labels to their appropriate locations in the table below.

Passive transport: How molecules move relative to a concentration gradient: down a concentration gradient Energy requirements: none Example: osmosis Active transport: How molecules move relative to a concentration gradient: against a concentration gradient energy requirements: requires energy from cells Example: sodium-potassium pump

Gigantism, a condition characterized by exceptionally rapid growth, is sometimes caused by a tumor that induces the gland in which it develops to overproduce a certain hormone. Where would such a tumor be expected to grow?

Pituitary gland.

Just as heat can denature enzymes, so can a change in the pH. Enzymes that normally work in an acidic environment in the body can become denatured if the pH becomes too alkaline. And enzymes that normally work in alkaline environments in the body can become denatured if the pH becomes too acidic. Taking an antacid to reduce the acidity (and increase the pH) of the stomach and to relieve heartburn can make a person more comfortable. What would be the major drawback to taking too many antacids?

Taking too many antacids could denature the enzymes that break down food in the stomach.

How is the production of hormones such as thyroxine and estrogen regulated?

The hypothalamus directs the anterior pituitary to produce hormones that then stimulate or inhibit the production of these hormones.

Does the penguin or the mouse expend a greater proportion of its energy budget on thermoregulation? Why?

The mouse expends a greater proportion of its energy budget on thermoregulation because of its small size.

Now look at the total annual energy expenditures for each animal. How much more energy does the penguin expend each year compared to the similarly sized python?

The penguin expends 42.5 times as much energy as the python.

Why does the pie chart for the python include growth but not thermoregulation?

The python grows throughout its life, and it is an ectotherm.

Lizards also thermoregulate and, as in humans, thermoregulation in lizards involves negative feedback. Lizards, however, are ectotherms and gain most of their heat from external sources. Therefore, they often use behavioral mechanisms to adjust their body temperature. For example, if a lizard's body temperature drops below its normal range, the lizard may seek a sunny resting spot to warm up. What are the stimulus and the response in this example? Drag the phrases on the left to complete the sentence on the right. Not all phrases will be used.

The stimulus is decreased body temperature, and the response is the behavior to seek a sunny spot.

What is the first thing that happens when body temperature increases above normal body temperature?

The thermostat in the hypothalamus activates cooling mechanisms.

What is the function of endocrine glands?

They release hormones into the bloodstream for distribution around the body.

True or false? The homeostatic system for blood calcium concentration is maintained by the hormones calcitonin and parathyroid hormone.

True

True or false? The pancreas is responsible for producing hormones that maintain the homeostatic levels of glucose in the blood.

True

Without considering the sizes of the wedges, how do the three pie charts differ in which functions they include?

Unlike the penguin and mouse charts, the python chart includes growth but does not include thermoregulation

What percent of the penguin's budget is for activity?

almost 50%

Homeostasis typically relies on negative feedback because positive feedback __________.

drives processes to completion rather than to a balance point

How do the following stimuli affect water and sodium (Na+) reabsorption in the kidneys? Drag each item to the appropriate bin.

increases water reabsorption ADH secretion sweating dehydration due to inadequate water intake eating salty food increases both water and Na+Na+ reabsorption blood loss aldosterone release severe diarrhea does not increase water or Na+Na+ reabsorption diabetes insipidus caffeine consumption alcohol consumption

Label the diagram of the kidney and nephron below. Drag the labels to their appropriate locations on the diagram below. Labels can be used once, more than once, or not at all.

look at pic

The kidneys of terrestrial mammals conserve water in the body by concentrating urine. The osmolarity of human blood is 300 mOsm/L, but human urine is generally about 1200 mOsm/L. The loop of Henle and the collecting duct are instrumental in maintaining osmotic gradients that make the concentration of urine possible.

look at pic

Thermoregulation in the body is accomplished by several feedback systems. The feedback system shown here uses vasoconstriction and vasodilation in the skin and extremities to regulate body temperature. Drag the labels to their appropriate locations on the diagram of the feedback system below. Labels can be used once, more than once, or not at all.

look at pic

Draw a model of the control circuit(s) required for driving an automobile at a fairly constant speed over a hilly road. Indicate each feature that represents a sensor, stimulus, or response.

look at pic (btw the middle two should be swapped, so sensor is above speedometer)

Homeostasis is the __________.

maintenance of a relatively constant and optimal internal environment

A countercurrent heat exchanger enables an animal to __________.

reduce the loss of body heat to the environment

Animals can be classified according to their mode of thermoregulation. Sort the animals below, indicating their likely thermoregulatory strategy. Note that poikilotherms are sometimes referred to as heterotherms. Drag each animal to the appropriate bin.

•homeothermic endotherm: walrus, eagle, coyote •homeothermic ectotherm: arctic shrimp •poikilothermic ectotherm: salamander, freshwater catfish, butterfly