9. The evolution of the vertebrate lung provides a classic example of how evolut
ID: 255267 • Letter: 9
Question
9. The evolution of the vertebrate lung provides a classic example of how evolution often builds upon pre-existing structures. The images below depict a swim-bladder organ present in the bony fishes (A), frog lungs (C), and a one reptilian lung (E). The small black lines in figures C) and E) represent infolding of the tissues. Swin bladder Esophagus or Pharynx A. The swim bladder of a fish Trachea intolding E. Reptile's lung C. Frog's lunge 9a. Describe the key function of the swim bladder organ in a bony fish such as the sturgeon. [4 pts] The swim bladder primarily functions as a hydrostatic organ. This enables the fish to maintain its depth without floating or sinking. 9b. Vertebrate lungs are thought to be derived from the swim bladder of a lobe-finned fish, which has a pulmonary artery that allows this swim bladder to function as a lung. Amphibian lungs are not as efficient as reptilian lungs. Explain a feature of amphibian gas-exchange anatomy that is advantageous for this vertebrate group based on its lifestyle. [2 pts] 9c. Based on the diagrams above, describe what features of the reptilian lung are responsible for its high efficiency as a gas exchange organ compared to the swim bladder and the amphibian lung structures. [2 pts]Explanation / Answer
9b. The amphibian have three respiratory surfaces on their body, which are used to exchange the gases. They are the skin, lungs and the lining of the mouth. Amphibians live on both the land as well as in the water. While they are completely submerged their body complete in the water all of their respiration takes place by their skin. The skin is composed of thin membrane and it is quite permeable to water. It contains a large network of blood capillaries. The thin membranous skin allow the respiratory gases to readily diffuse down the concentration gradient between the blood capillaries and the surrounding. When the amphibian are out of the water, the mucus gland of the skin keep them moist which helps to absorb oxygen from the air.
9c. We all know that the surface of the lungs are full of blood capillaries. As the membrane of the capillaries are very thin, so the exchange of gases can take place easily and efficiently through it. As the reptilian lung consists of maximum number of folds, then it naturally contains more blood capillaries than the amphibian lung as well as the swim bladder. So, the reptilian lungs are responsible for it's high efficiency as a gas exchange organ.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.