What do the alveoli of mammalian lungs, the gill filaments of fish, and the tracheoles of insects all have in common?
a. They use a circulatory system to transport absorbed O2.
b. Their respiratory surfaces are invaginated.
c. They function using countercurrent exchange.
d. They have a large, thin surface area for gas exchange.
e. All of the listed responses are correct.
Answer: d. They have a large, thin surface area for gas exchange.
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Answer the following statements true (T) or false (F)
1. RNA polymerase can bind to the promoter region of the DNA even when the lac repressor is bound to the operator site. 2. Both eukaryotes and prokaryotes require a promoter region for gene transcription. 3. A cis-effect is a form of gene regulation that can occur between two DNA segments that are not physically adjacent. 4. Eukaryotic genes are almost always organized in groups, similar to operons in prokaryotes.
How does a positive regulator affect transcription by RNA polymerase in prokaryotes?
A) by allowing passage of the polymerase through an operator B) by interacting with RNA polymerase to increase the frequency of transcription initiation C) by causing the helix to unwind in the operator allowing easier initiation D) by making the transcription start site more exposed to the polymerase
Which of the following is true about polio?
a. it is an X-linked genetic disease b. it has been virtually eliminated worldwide c. it is a disease that kills motor neurons d. it most frequently affects adults e. all of these are true about polio
________ is caused by excessive pressure in the aqueous humor
Fill in the blank(s) with correct word