The paranasal sinuses, together with other structures of the upper respiratory tract, A) are where a small percentage of gas exchange occurs.
B) form part of the respiratory membrane.
C) are involved in filtering, warming, and humidifying incoming air.
D) provide a large area for gas exchange between air and circulating blood.
E) are lined by a delicate simple squamous epithelium.

1. true.2. true.3. true.4. false.5. true.the concept of darwin's theory of evolution involves the idea that there are limited resources in a given living environment and that the organisms which live within have variations in their genetic make up due to random mating. the ones with beneficial genetic variations can express certain traits which give them an upper hand in surviving and reproducing in the said environment compared to ones who may have a more disadvantageous variation in traits. over time, the organisms with an upper hand will survive and reproduce more frequently and pass on their beneficial genes while the others die. the result is evolution, where we observe (usually, but not always) eventually, phenotypic distinct changes.

Ithink the dna sequences may vary but the amino acid sequences are identical.