Question

1 name at least two structures in the avian respiratory system that are not present in mammals.
2 what unusual excretory organ do birds possess on their heads?
3 what organ in birds secretes an oily compound to waterproof the feathers?
4 how many chambers does a birds heart possess? is this more similar to the heart of reptiles or to that of mammals?
5 describe respiration in birds, noting the advantages of air sacs.
6 what anatomical features of birds permit them to maintain constant and relatively high internal body temperatures?
7 identify several anatomical similarities between birds and reptiles that reflect the common evolutionary lineage of these two groups.

Explanation:

1. Avian respiratory systems have air - sacs and syrinx not in mammals. Air - sacs aid in efficient gas exchange and the syrinx is for vocalization.
2. Birds do not have an unusual excretory organ on their heads.
3. The preen gland (uropygial gland) secretes an oily compound for feather waterproofing.
4. A bird's heart has 4 chambers, more similar to mammals. Reptiles usually have 3 - chambered or incomplete 4 - chambered hearts.
5. In bird respiration, air sacs allow for unidirectional air flow, increasing gas exchange efficiency and cooling the body.
6. Birds have high metabolic rates, feathers for insulation, and efficient circulatory systems to maintain high body temperatures.
7. Birds and reptiles have similar features like scales (modified in birds as scutes on legs), amniotic eggs, and similar skeletal structures in some parts.

Answer:

1. Air - sacs, syrinx
2. None
3. Preen gland (uropygial gland)
4. 4 chambers, more similar to mammals
5. Air sacs enable unidirectional air flow, enhancing gas exchange and cooling.
6. High metabolic rate, feathers, efficient circulatory system
7. Scales (modified as scutes on bird legs), amniotic eggs, some similar skeletal structures