Biology Chapters 42-49

Doctors sometimes prescribe proton pump inhibitors to treat patients with acid reflux. How do these drugs work?

A proton pump inhibitor reduces activity of the proton pumps in parietal cells, reducing the amount of HCl produced. The contents of the stomach would therefore become less acidic, helping to prevent acid reflux.

Which of the following animals is least likely to have a well-developed vomeronasal organ? A. fish B. salamander C. rodent D. snake

A. fish Vomeronasal organs evolved in tetrapods, presumably as an adaption for communication in terrestrial habitats

Which of the following organisms would lose the most water by osmosis across its gills? A. marine bony fish B. shark C. freshwater bony fish D. freshwater invertebrate

A. marine bony fish

Which of the following developmental processes is not controlled by hormones? A. the initial development of male and female gonads, soon after fertilization B. overall growth C. molting in insects and other invertebrate animals D. metamorphosis in insects and other invertebrate animals

A. the initial development of male and female gonads, soon after fertilization

In muscle cells, myosin molecules continue moving along actin molecules as long as...

ATP is present and intracellular Ca2+ is high

Consider the following: absorptive sections of digestive tract, capillaries, beaks of Galapagos finches, and fish gills. In each case, how does the structure relate to the function?

Absorptive sections have many folds and projections that increase their surface area for absorption. Capillaries have high surface area because they are thin and highly branched, making exchange of fluids and gases efficient. Beaks of Galapagos finches have sizes and shapes that correlate with the type of food each species eats. Large beaks are used to crack large seeds; long, thin beaks are used to pick insects off surfaces; etc. Fish gills are thin, flattened structures with a large surface area, which facilitates the efficient exchange of of gases and wastes.

Compare and contrast the types of nitrogenous wastes observed in animals. Identify which compound can be excreted with a minimum of water, which is most toxic, and which waste product is found in fishes, in mammals, and in insects. Which type of nitrogenous waste would you expect to find produced by embryos inside eggs laid on land?

Ammonia is toxic and must be diluted with large amounts of water to be excreted safely. Urea and uric acid are safer and do not have to be excreted with large amounts of water but are more expensive to produce in terms of energy expenditure. Fish excrete ammonia; mammals excrete urea; insects excrete uric acid. You would expect the embryos inside terrestrial eggs to excrete uric acid, since it is the least toxic and is insoluble in water.

Describe the ways in which an open circulatory system is less efficient than a closed circulatory system.

An open circulatory system is less efficient than a closed circulatory system because it is not capable of directing the hemolymph toward specific organs, and because the pressure is lower, resulting in slower flow of hemolymph.

Under certain conditions, cells produce a metabolic byproduct called 2, 3-diphosphoglycerate (DPG). Which of the following would support the hypothesis that DPG helps increase oxygen unloading from tissues? A. DPG shifts the oxygen-hemoglobin equilibrium curve to the left B. DPG decreases percentage saturation of hemoglobin with oxygen at a PO2 of 30 mm Hg. C. DPG increases the pH of the tissues D. DPG is produced in greater quantity at low altitude than at high altitude

B. DPG decreases percentage saturation of hemoglobin

O2 will diffuse from blood to tissue faster in response to which of the following conditions? A. an increase in the PO2 of the tissue B. a decrease in the PO2 of the tissue C. an increase in the thickness of the capillary wall D. a decrease in the surface area of the capillary

B. a decrease in the PO2 of the tissue

Which of the following brain regions is responsible for formation of new memories? A. brain stem B. hippocampus C. frontal lobe D. cerebellum

B. hippocampus

Suppose a friend of yours is trying to decide whether to buy a pet turtle or a pet mouse. In making the decision, all he cares about is how much it will cost to feed the animal. Your friend says he can't decide because the two animals weigh the same and their food costs the same per pound. As a biologist, what's your advice?

Buy the turtle, because it is an ectotherm and will therfore consume less food than the mouse. Turtles are ectothermic, so they do not expend much energy to produce body heat. Mice are endothermic, and expend energy to regulate body temperature. Mice will therefore have a higher basal metabolic rate and consume more food.

Which is the following is an example of negative feedback? Explain why each is or is not negative feedback. A. Uterine contractions during childbirth stimulate release of a hormone that stimulates more uterine contractions B. A viral infection stimulates the hypothalamus to increase the set point for body temperature C. High blood sugar concentrations stimulate the release of the hormone insulin, which stimulates the sugars to move from the blood into the cells D. The body temperature of the Arabian oryx rises during the hottest parts of the day

C. High blood sugar concentrations stimulate the release of the hormone insulin, which stimulates the sugars to move form the blood into the cells. This is an example of negative feedback because insulin is released in response to an increase in parameter (blood sugar concentration)

Which of the following is a neurotransmitter that stimulates contraction of skeletal muscle? A. norepinephrine B. adrenaline C. acetylcholine D. calcium

C. acetylcholine

Which of the following does blood not do? A. transport O2 and CO2 B. distribute body heat C. produce new red blood cells and other formed elements D. buffer against pH changes

C. produce new red blood cells and other formed elements

Which of the following is not an advantage of breathing air over breathing water? A. Air is less dense than water, so it takes less energy to move during ventilation B. Oxygen diffuses faster through air than it does through water C. The oxygen content of air is greater than that of an equal volume of water D. Air breathing leads to high evaporation rates from the respiratory surface

D. Air breathing leads to high evaporation rates from the respiratory surface

Which of the following best describes the set point in a homeostatic system? A. the cells that collect and transmit information about the state of the system B. the cells that receive information about the state of the system and that direct changes to the system C. the various components that produce appropriate changes in the system D. the target or "normal" value of the parameter in question

D. the target or "normal" value of the parameter in question

Why are many digestive enzymes produced in an inactive form and then activated in the lumen of the digestive tract?

Digestive enzymes break down macromolecules (proteins, carbohydrates, nucleic acids, lipids). If they weren't produced in an inactive form, they would destroy the cells that produce and secrete them.

Describe the changes in oxygen delivery that occur as a person proceeds from a resting state to intense exercise.

During exercise, PO2 decreases in the tissues and PCO2 increases. The increase in PCO2 lowers tissue pH. The drop in PO2 and pH causes more oxygen to be released form the hemoglobin.

Both epinephrine and cortisol are involved in he body's response to stress. How do the two molecules differ?

Epinephrine mediates the short-term response; cortisol mediates the short and long term responses

---- tissues form the interface between the inside of an animal's body and the environment.

Epithelial

True or False: A large animal will experience twice the gravitational forces of a small animal half its size if their geometries are the same.

False

True or False: Type 1 diabetes mellitus is more prevalent in the United States than type 2 diabetes mellitus.

False

Biologists recently have been able to produce mice that lack functioning genes for aquaporins. How does their urine compare to that of individuals with normal aquaporins?

Higher volume and lower osmolarity Without aquaporins in the collecting duct, water cannot be reabsorbed, which would result in increased urine volume and decreased urine osmolarity.

What do the shapes of human teeth suggest about their function in terms of the types of food humans are adapted to eat?

Humans have sharp canines and incisors, which may help to bite and tear meat. Humans also have flat molars, which help in grinding grains and other plant material.

Explain how most carbon dioxide is transported in the blood. In humans, why don't intense exercise and rapid production of CO2 lead to a rapid reduction in blood pH?

In blood, CO2 is ocverted to carbonic acid, which dissociates into a proton and a bicarbonate ion. Because the protons bind to deoxygenated hemoglobin, they do not cause a dramatic drop in blood pH (hemoglobin acts as a buffer). Also, small decreases in blood pH trigger a homeostatic response that increases breating rate and expulsion of CO2.

Predict the effect of ingestion of the toxin atropine on heart rate. Atropine is a naturally occurring compound in many poisonous nightshade plants. It blocks acetylcholine receptors in the heart. Explain your logic.

In cardiac muscle, the binding of acetylcholine to its receptors causes the heart rate to slow. Ingestion of nightshade would increase heart rate because it blocks acetylcholine receptors.

What effect does antidiuretic hormone (ADH) have on the nephron?

It increases water permeability of the collecting duct.

How does myelination affect the propagation of an action potential?

It speeds propagation because cations do not leak out of the membrane as they spread down the axon

Why did the squid axon become a model system for studying electrical signaling in animals?

It was large enough to support intracellular recording by the first microelectrodes

What does it mean to say that an animal is a heterothermic endotherm?

Its body temperature varies, but most of its heat is produced by its own tissues

As an animal gets larger, what occurs? (volume and surface area)

Its volume and surface area increase in perfect proportion to each other

Which ion leaks across a neuron's membrane to help crate the resting potential?

K+

Explain how each parameter in Fick's law of diffusion is reflected in the structure of the mammalian lung.

Lungs increases the temperature of the air and are moist to allow greater solubility of gases (increasing k); alveoli present a large surface area (large A); the epithelium of alveoli is thin (small D); the constant delivery of deoxygeated blood to alveoli maintains a steep partial pressure gradient, favoring diffusion of oxygen into hte body (P2-P1 is high).

Where are the photoreceptors that sense day length located in mammals? In lizards? In birds?

Mammals - eye and pineal gland Lizards - pineal gland Birds - diffuse in brain

In a neuron, what creates the electrochemical gradient favoring the outflow of K+ when the cell is at rest?

Na+/K+-ATPase

How does the high type 2 diabetes mellitus rate among Pima Indians in the United States provide evidence for an environmental effect on development of the disease?

Pima living in the United States are genetically similar to Pima living in Mexico, but they have higher rates of type 2 diabetes. This suggests that the difference in diabetes rates is due to environmental factors such as diet and exercise.

What is the correct sequence of the regionsof the nephron with respect to fluid flow? (ascending limb of loop of Henle, distal tubule, proximal tubule, descending limb of loop of Henle, collecting duct)

Proximal tubule - descending limb of loop of henle - ascending limb of loop of Henle - distal tubule - collecting duct

How do steroid hormones differ from polypeptide hormones and most amino-acid-derived hormones?

Steroids are lipid soluble and cross plasma membranes readily

Design a study to test the hypothesis that the symptoms of jet lag are caused by disruption of normal daily cortisol rhythms

Subject volunteers to travel and jet lag, measure ACTH and cortisol levels, and correlate these results with their perceived level of jet lag symptoms

Explain why the Na+/K+-ATPase is "electrogenic" - meaning that it creates a voltage across a membrane.

The Na+/K+-ATPase pumps 3 Na+ out of the cell for every 2 K+ it brings in. Since more positive charges leave the cell than enter it, there is a difference in charge on the two sides of the membrane and thus a voltage.

Explain how the structure of each of the following digestive tract compartments correlates with its function: the bird crop, cow rumen, and elephant large intestine.

The bird crop is an enlarged sac that can hold quickly ingested food; in leaf-eating species it is filled with symbiotic organisms and functions as a fermentation vessel. The cow rumen is an enlarged portion of the stomach; the elephant cecum is enlarged relative to other species. Both structures are filled with symbiotic organisms and function as fermentation vessels.

If you have seen the film Jurassic Park, you can imagine the nightmarish sight of Tyrannosaurus rex in high-speed pursuit of you as you flee in a jeep. Evaluate whether the data collected on the biomechanics of locomotion in living species are sufficient to determine how fast a large dinosaur like T. rex could run.

The bones of T. rex are available and can be analyzed to determine their structural properties, such as the mechanical advantage of the leg joints and the ability of the bones to withstand the different forces that the skeleton would experience at different speeds based on date from living animals. A very close estimate could be made, but the exact speed would b hard to determine without observing the dinosaur in action, since behavior affects speed.

An engineer has to design a system for dissipating heat from a new type of car engine that runs particularly hot. Recall that heat is gained and lost as a function of surface area. Suggest ideas to consider that are inspired by biological structures with exceptionally high surface area/volume ratios.

The heat-dissipating system should have a very high surface area/volume ratio. Based on biological structures, it should be flattened (thin) and highly folded and branched, and/or contain tubelike projections.

To test the hypothesis that mussels are osmoconformers, researchers exposed mussels to water of varying osmorlarities and then drew hemolymph samples from the mussels. In the researchers' hypothesis supported by the data, shown below? Explain.

The hypothesis that the mussels are osmoconformers is supported because their hemolymph is very close in osmolarity to that of the wide range of water osmolarities into which they are placed.

Explain the difference between a ligand-gated K+ channel and a voltage gated K+ channel.

The ligand-gated channel opens or closes in response to binding by a small molecule (for example, a neurotransmitter); the voltage-gated channel opens or closes in response to changes in membrane potential.

Explain why drugs that prevent neurotransmitters from being taken back up by the presynaptic cell have dramatic effects on the activity of postsynaptic neurons.

The neurotransmitters will stay in the synaptic cleft linger, so the amount of binding to ligand-gated channels will increase. Ion flows into the postsynaptic cell will increase dramatically, affecting its membrane potential and likelihood of firing action potentials.

Compare and contrast the structure and function of the anterior and posterior pituitary glands

The posterior pituitary is an extension of the hypothalamus; the anterior pituitary is independent - it communicates with the hypothalamus via chemical signals in blood vessels. The posterior pituitary is a storage area for hypothalamic hormones;the anterior pituitary synthesizes and releases an array of hormones in response to releasing hormones form he hypothalamus

Compare and contrast the somatic and atonomic components of the PNS.

The somatic system responds to external stimuli and controls voluntary skeletal muscle activity, such as movement of arms and legs. The autonomic system controls internal involuntary activities, such as digestion, heart rate, and gland activities.

In insects, what is the adaptive significance of spiracles?

They close off tracheae to minimize water loss

For fishes that live in freshwater - True or False: Water enters epithelial cells in their gills via osmosis. Electrolytes leave the same cells via diffusion.

True

True or False: In hormone systems, feedback inhibition occurs when the presence of a hormone inhibits release of the hormone.

True

True or False: Sodium-potassium ATPase pumps move three sodium molecules out of a cell in exchange for two potassium ions, establishing an electrochemical gradient.

True

True or False: The increase in red blood cell count in tourists visiting Tibet is an example of acclimatization.

True

True or false: Sodium ions from foods can directly depolarize certain taste cells

True

What promotes oxygen release from hemoglobin?

a decrease in pH

What is an incomplete digestive tract?

a digestive system with a single opening for ingestion and excretion

What is a hormone-response element?

a segment of DNA where a hormone-receptor complex binds

In he human ear, how do different hair cells respond to different frequencies of sound?

because the basilar membrane varies in stiffness, it vibrates in certain places in response to certain frequencies

In Gila monsters, the organ in which water from urine is reabsorbed into the bloodstream is the ----.

bladder

In mammals, how and where are carbohydrates digested?

by amylases in the mouth and small intestine

Hormones are present in tiny concentrations, yet have large effects on target cells and on the individual as a whole. This is possible because a single hormone molecule...

can activate many intracellular enzymes

Cellulose is fermented in which structure in rabbits?

cecum

A hormone that reduces blood glucose is ----, while a hormone that increases blood glucose is ----.

insulin; glucagon

What does secretin stimulate?

secretion of HCO3- from the pancreas

If a sprinter began an endurance running program, what would occur?

some fibers wold develop a higher mitochondrial density

What is echolocation?

use of echoes from high-frequency vocalizations to detect objects