Which of these groups is characterized by a lack of symmetry (neither radial nor bilateral)?
A) Cnidarians B) Chordates C) Arthropods D) Flatworms E) Sponges
E
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Which of the following is a transition mutation?
A) ACC to CCC B) A to G C) GG to AA D) A to T
The aortic semilunar valve opens when the
A) arterial pressure is lower than the ventricular pressure. B) right ventricle is in diastole. C) atrioventricular valves open. D) atrium is in systole. E) pulmonary semilunar valve closes.
Which phylum includes members that have a body divided into three regions called the visceral mass, head-foot, and mantle?
a. Rotifera b. Mollusca c. Nemertea d. Platyhelminthes
How can urine contain a higher concentration of wastes (be hypertonic) than the blood?
Select one: a. Urine cannot since the process is passive diffusion. b. Reabsorption of water in the loop of the nephron and collecting ducts leaves behind a more concentrated urine. c. All stages in the kidney involve active transport. d. Urine can be hypertonic for small molecules if it is hypotonic for an equal number of big molecules. e. The whole nephron is impermeable to water.