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At the completion of this exercise you should: Be able to define and contrast the anatomical terms Homologous and Analogous.

At the completion of this exercise you should: Be able to define and contrast the anatomical terms Homologous and Analogous.

Daniel Kevins

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question 1. Place the letter A for analogous or the letter H for homologous next to the pairs of structures below.

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		Homologous/ Analogous?
human arm	cat forelimb
bat wing	frog forelimb
bird wing	butterfly wing
horse forelimb	bird wing
paired whale flippers	paired fish fins

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Question 2. List some general similarities in the skulls of the cat, horse, and man.

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Question 3. Examine the sutures joining the several bones of the skulls. How are the skulls generally comparable in terms of the number and types of bones?

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Question 7. Generally, bones provide structure to the organism, acting as points of attachment for soft tissues. What do you suppose to be the specific function of the zygomatic arch?

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Question 8. Locate and count the above tooth types in your own mouth. Which ones are you missing, compared to the formula?

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Question 9. How are the canines of a cat different from those of the human?

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Question 10. Compare the shapes and numbers of premolars and molars between the cat and the human:

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	Cat	Human
Premolars: Number
Premolars: Shape
Molars: Number
Molars: Shape

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Question 11. Do any of the teeth (cat or human) appear to be specialized? If so, which ones and for what?

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	Incisors	Canines	Premolars	Molars
Cat: Description:
Specialized?
Purpose?

Human: Description:
Specialized?
Purpose?

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Question 12. On the basis of your observations and on your knowledge of the diet of a cat, write a general statement summing up the adaptive features observed in the teeth of the cat.

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Question 13. How do the teeth of the rodent (e.g., beaver) differ from those of the cat? Consider both number and type of teeth.

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Question 14. Do the differences between the rodent (beaver) teeth and cat teeth represent a specialized or generalized feature? Explain your answer.

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Question 15. How do the teeth of the horse differ in number and form from the cat?

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Question 16. How are the teeth of the horse adapted to its particular environment and way of life?

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Question 17. Which basic tooth type is exaggerated in the dentition of the pig?

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Question 18. Of what adaptive significance are tusks as illustrated in the pig?

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Question 19. In a sentence, indicate the type of teeth you might expect to find in an animal which swallows its prey whole?

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Question 20. What common animal employs the type of teeth described in Question 19?

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Question 21. List some similarities between the bones in the human arm and leg.

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Question 22. List some differences between the bones in the human arm and leg.

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Question 23. The human skeleton consists of 206 bones. There are 106 bones in the wrists, hands, ankles and feet. What is the advantage of having this many bones? Explain.

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Question 24. Observe the diagrams of the forelimbs. On the list of the six kinds of bones below, place the respective numbers indicating a specific bone type in the blanks below after the named skeletal bone. As an example, this has been done for the humerus. (See also Figure 2.)

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Humerus	11, 17, 5, 1
Radius
Ulna
Carpals
Metacarpals
Phalanges

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Question 25. Compare the size and shape of the three brain divisions as you observe the models: for each part, estimate the percent of the total brain mass it occupies.

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(Note: The human model is not color-coded the same as the rest.

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Use the chart provided to locate the parts of the human brain.)

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Estimated Percent of Total Brain Mass

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Species	Optic Lobes	Cerebellum	Cerebrum
Trout (Salmo)
Frog (Rana)
Pigeon (Columba)
Dog (Canis)
Human (Homo)	*

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The ratio between the weight of the brain and spinal cord can serve as a general criterion for an animal’s relative intelligence. Fish and amphibian brains have a ratio of 1:1, while the human brain has a ratio of 55:1 (or 55 times heavier than the spinal cord).

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*Not found in human brain—optic lobe function taken over by occipital lobes of cerebrum.

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Question 26. Do all of the following organisms have teeth to grind up their food? If not, attempt to explain why they don’t need teeth.

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frog:

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turtle:

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seed-eating birds:

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pig:

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Question 27. With what structure does the frog capture its food?

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Question 28. Some food types are more difficult to digest and therefore require more time in the digestive tract. Suggest an anatomical adaptation that would increase the length of time the food remains in the digestive tract, as well the surface area available for absorption of food molecules.

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Question 29. Do the liver and pancreas appear in all of our study animals?

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What are some important functions of these organs (related to digestion)?

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Question 30. In an animal such as the fish, oxygen enters the blood through the tissues of the gills with their rich capillary supply by diffusion from the oxygen in the water. How many chambers are present in the heart of the perch?

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One of the chambers of the fish heart (atrium) receives blood and the other (ventricle) pumps it to the gills and then on to the rest of the body.

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Question 31. How many chambers are seen in the heart of the frog?

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How many chambers are seen in the heart of the turtle?

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How many chambers are seen in the hearts of the mammals?

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Question 32. Observe the lungs of the frog and turtle and compare with those of the fetal pig, bird, and cat. Do you suppose that frogs and turtles require as much oxygen (per gram body weight) as pigs, birds and cats?

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Can you also relate this to the presence or absence of thermoregulation in these animals?

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Daniel Kevins

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