Question

1.    During lab you observed several animals that use gills for respiration. How were they all similar? Were there any differences between them? How do you account for these differences?

2.    Are the nostrils of sharks and perch used for breathing? What structural features of the nostril helped you arrive at your answer?

3.    Compare and contrast the gill structure of crayfish and perch. Provide two similarities and two differences in your response.

4.    How does the slide of a mammalian lung provide a good example of the relationship between structure and function?

5.    Compare and contrast the lung of a frog and rat. Provide two similarities and two differences in your response. Explain a reason for these differences.

Answer 1

#1. A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. In some aquatic species like crabs, allow respiration on land when they are kept on moisture. In addition to this, some aquatic insects contains blood, from which the gases are exchanged through their thin walls. In these species, the blood carries oxygen to other parts of the body whereas the carbon dioxide are passed from the blood through the gills in to the water. #2. NO. All fishes are aquatic and they have gills for respiration. The nostrils are used to detect the presence of food in the water. Shark gills are just behind the shark head, and they do not have covers like most other fishes. Perches have gills. Gill filaments contains capillaries. Water enters pharynx from mouth, passes over gills and oxygen goes in to capillaries. #3. COMPARISON : They both respires through gills and contains a capillary network called filament that provides a surface area for exchanging oxygen and carbon dioxide. CONTRAST: In perch, the gills are covered by operculum or opercular bone and have nostrils. In crayfish, the gills are present in both the sides of the cephalothorax and gill arch helps in feeding tiny prey. #4.The lungs of mammals are unique in having alveoli and have tiny-sac like structures surrounded by small blood vessels. The circulation of the dermis is out of proportion to the nutritional status of the tissue to reduce body temperature and blood pressure. #5. COMPARISON: The rat lungs are too small compared to frog and the size of the rat's lung is much closer to the frog's lungs. CONTRAST:1. The expansion of the lungs are too small in frog than rats. 2. The lungs of the frog are round and flat in rats.