Exam 1 - Zoology 250

Version A KEY

Terminology/Short Answer (1 pt. each except where noted) - these questions require only terms or brief answers. We will not mark down for spelling, but we must be able to recognize the word to give credit.

  1. What is a motor unit?



    - a motor neuron and the muscle fibers it innervates

  3. A vascular arrangement where the arterial supply to and venous return from a structure are positioned right next to each other is referred to as a:



    - rete

  5. Which type of muscle is responsible for peristalsis along the digestive tract?



    - smooth muscle

  7. Bones are connected to each other by:



    - ligament

  9. Briefly, in what ways is the circulatory system well adapted to function as an exchange surface for diffusion? (3 pts.)



    Distance: endothelium is very thin, minimizing diffusion distance
    Area: capillaries collectively have a huge surface area (~700 m2 in humans)

    Gradients: Circulation keeps blood moving, preventing equilibrium and maintaining concentration gradients

  11. Briefly, list two mechanisms by which the stomach is protected from digesting itself. List only two. (2 pts.)
Three are possible here:
  1. Pepsin is in inactive form (pepsinogen) until activated in the stomach
  2. stomach epithelium is many cell layers thick and continuously replaced
  3. mucus production in the stomach provides a protective coating
7. Briefly explain the reason why tension development is greatest at the 2.00 and 2.25 mm sarcomere length on the figure shown below. You should explain in terms of the molecular details of muscle contraction (2 pts).

Tension is greatest when the greatest number of myosin-actin crossbridges are formed. The overlap of thick and thin filaments at 2-2.25 mm is greatest and allows the largest number of crossbridges to be formed.

Multiple Choice: Use the Scantron sheet for these questions

1. Hydrostatic skeletons are normally used for movement by all of the following animals EXCEPT:
a) annelids
b) cnidarians
c) crustaceans
d) nematodes
e) flatworms

2. Which of the following is a problem that had to be solved as animals increased in size?
 X. decreasing surface-to-volume ratio
 Y. reproducing in aqueous environments
Z. increasing tendency for larger bodies to be more variable
a) X only
b) Y only
c) Z only
d) X and Y only
e) X and Y and Z

3. What is the role of calcium in muscle contractions?
a) to break the cross-bridges as a cofactor in the hydrolysis of ATP.
b) to bind with troponin, changing its shape so that the actin filament is exposed.
c) to transmit the action potential across the neuromuscular junction.
d) to spread the action potential through the T-tubules.
e) To re-establish the polarization of the plasma's membrane following an action potential.

4. A sustained contraction of muscle due to a succession of stimuli with no time between the stimuli for relaxation is called...
a) tonus
b) tetanus
c) all-or-none response
d) fatigue
e) spasm

5. Muscle cells are stimulated by neurotransmitters released from the tips of ...
a) T-tubules
b) motor cell axons
c) sensory cell axons
d) motor cell dendrites
e) sensory cell dendrites

6. In the disease Myasthenia gravis, there is a deficiency of acetylcholine receptors at the neuromuscular junction.  This blocks contraction by preventing muscle activation at which point:
a) generation of action potentials in the motor neuron
b) opening of the t-tubule system
c) release of Ca2+ from the sarcoplasmic reticulum
d) altering the interaction of troponin with tropomyosin
e) generation of action potentials in the muscle cell

7. When an organism dies, its muscles remain in a contracted state termed rigor mortis for a brief period of time.  Which of the following most directly contributes to this phenomenon?
a) no ATP to move cross-bridges
b) no ATP to break bonds between thick and thin filaments
c) no calcium to bind to troponin
d) no oxygen supplied to muscle
e) no energy for the synthesis of actin and myosin

8. The breast muscle of turkeys and chickens is usually referred to as light meat, whereas that of wild ducks and geese is described as dark meat.  Which of the following is consistent with this observation?
a) Turkeys and chickens are not closely related to ducks and geese.
b) Turkeys and chickens do not use their breast muscle, whereas ducks and geese do.
c) Turkeys and chickens do not fly for sustained periods; ducks and geese do.
d) The muscles of these two groups of birds contain different filamentous proteins.
e) The darker body color of ducks and geese provides protective camoflage against predators.

9. Which of the following could you find in the lumen of a transverse tubule?
a) extracellular fluid
b) cytoplasm
c) actin
d) myosin
e) sarcomeres

10. Living bone cells are found in spaces termed _____ and connected to each other by cytoplasmic connections passing through _____.
a) lacunae, canaliculi
b) canaliculi, Haversian systems
c) lacunae, Haversian systems
d) canaliculi, osteoclasts
e) none of the above

11.  Cardiac muscle is which of the following?
a) striated & branched
b) striated & unbranched
c) smooth & voluntary
d) striated & voluntary
e) smooth & involuntary

12.   Which of the following traits is characteristic of ALL types of muscle tissue?
a) intercalated discs that allow cells to communicate
b) striated banding pattern seen under the microscope
c) cells that lengthen when appropriately stimulated
d) response that can be consciously controlled
e) cells that contain actin and myosin

13.  Which of the following statements concerning the relationship of energy expenditure to body size in animals is TRUE?
a) Large endotherms have higher specific metabolic rates (O2/g tissue/hour) than small endotherms.
b) Large ectotherms have lower specific metabolic rates than small ectotherms.
c) There is an inverse (i.e., negative) relationship between the total energy used by an animal and its body size.
d) Only endotherms show an inverse relationship between specific metabolic rate and body size.

14.  An increase in which of the following parameters is most important in the evolution of specialized exchange surfaces such as the linings of the lungs or intestines?
a) surface area
b) thickness
c) number of cell layers
d) metabolic rate of its component cells
e) volume of its component cells

15.  Cows are able to survive on a diet consisting almost entirely of cellulose because...
a) cows are autotrophic.
b) the cow, like the rabbit, reingests its feces.
c) cows can manufacture all 20 amino acids out of sugars in the liver
d) unlike humans, the saliva the cow produces has enzymes capable of digesting cellulose
e) cows have cellulose-digesting, symbiotic microorganisms in their rumens

16.   All of the following statements about digestion are correct EXCEPT:
a) Digestion is catalyzed by enzymes.
b) Digestion cleaves nucleic acids into nucleotides.
c) Digestion cleaves fats into glycerol and fatty acids.
d) During digestion, the essential macromolecules are directly absorbed.
e) During digestion, polysaccharides and disaccharides are split into simple sugars.

17. What is peristalsis?
a) a process of fat emulsification in the small intestine
b) voluntary control of the rectal sphincters regulating defecation
c) the transport of nutrients to the liver through the hepatic portal vein
d) loss of appetite, fatigue, dehydration, and nervous disorders
e) smooth muscle contractions that move food through the alimentary canal

18.   Most nutrients are absorbed across the epithelium of the...
a) colon
b) stomach
c) esophagus
d) small intestine
e) large intestine

19.   Which of the following is a correct statement about pepsin?
a) It is manufactured by the pancreas.
b) It helps stabilize fat-water emulsions.
c) It splits maltose into monosaccharides.
d) It is activated by the action of HCl on pepsinogen.
e) It is denatured & rendered inactive in solutions with low pH.

20.   Blood sugar concentration is likely to vary most in which of these blood vessels?
a) the abdominal artery
b) the coronary arteries
c) the pulmonary veins
d) the hepatic portal vein to the liver

21.  During the process of digestion, fats are broken down when fatty acids are detached from glycerol; and proteins are degraded when amino acids are separated from each other.  What do these 2 processes have in common?
a) Both processes can be catalyzed by the same enzyme.
b) Both processes occur intracellularly in most organisms.
c) Both involve the addition of a water molecule to break bonds.
d) Both require the presence of hydrochloric acid to lower pH.
e) Both require ATP as an energy source.

22.   How does the digestion & absorption of fat differ from that of carbohydrates?
a) Processing of fat does not require any digestive enzymes, whereas the processing of carbohydrates does.
b) Fat absorption occurs in the stomach, whereas carbohydrates are absorbed from the small intestine.
c) Carbohydrates need to be emulsified before they can be digested, whereas fats do not.
d) Most absorbed fat enters the lymphatic system, whereas carbohydrates directly enter the blood.
e) Fat must be worked on by bacteria in the large intestine before it can be absorbed, which is not the case for carbohydrates.

23.   Which of the following glandular secretions involved in digestion would be most likely to be released initially as zymogens?
a) protein-digesting enzymes
b) fat-solublizing bile salts
c) acid-neutralizing bicarbonate
d) carbohydrate-digesting enzymes

24.   What is the reason why fluid is forced out of systemic capillaries at the arteriolar end?
a) The osmotic pressure of the interstitial fluid is greater than that of the blood.
b) The hydrostatic pressure of the blood is less than that of the interstitial fluid.
c) The hydrostatic pressure of the blood is greater than the osmotic pressure of the interstitial fluid.
d) The osmotic pressure of the interstitial fluid is greater than the hydrostatic pressure of the blood.
e) The osmotic pressure of the blood is greater than the hydrostatic pressure of the interstitial fluid.

25. If, during protein starvation, the osmotic pressure on the venous side of capillary beds drops below the hydrostatic pressure, then...
a) hemoglobin will not release oxygen.
b) fluids will tend to accumulate in tissues.
c) the pH of the interstitial fluids will increase.
d) most CO2 will be bound to hemoglobin & carried away from tissues.
e) plasma proteins will escape through the endothelium of the capillaries.

26. Through how many capillary beds must a red blood cell of a human travel, if it takes the shortest possible route from the right ventricle to the right atrium?
a) 1
b) 2
c) 3
d) 4
e) 5

27.   Which of the following are the only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart?
a) Amphibians
b) Birds
c) Fishes
d) Mammals
e) reptiles

28.  The meshwork that forms the fabric of a blood clot mostly consists of which protein?
a) fibrogenin
b) fibrin
c) thrombin
d) prothrombin
e) collagen

29.  If the atrioventricular node could be surgically removed from the heart without disrupting signal transmission to the Bundle of His, then....
a) no apparent effect on heart activity would be observed.
b) the heart rate would be decreased.
c) only the ventricles would contract.
d) only the atria would contract.
e) atria & ventricles would contract at about the same time.

30. If a person were suffering from edema such as is seen in elephantiasis, which of the following conditions would reduce it?
a) decreased plasma protein production by the liver.
b) a prolonged starvation diet.
c) an obstruction in the lymphatic system.
d) lower blood pressure.
e) enlarged clefts between capillary endothelial cells due to damage or inflammation.