Freshwater flatworms have this type of system for osmoregulation.
A. protonephridial
B. metanephridial
C. osmonephridial
D. eunephridial
E. isonephridial
A. protonephridial
You might also like to view...
Melvin Calvin used ________, a specific ________, to deduce the Calvin-Benson cycle of photosynthesis.
Fill in the blank(s) with the appropriate word(s).
Why is nitrogen fixation by prokaryotes essential to life on Earth?
a. It removes nitrogen from the soil. b. It converts atmospheric nitrogen to a non-toxic form. c. It provides nitrogen sources for plants and animals. d. It provides an energy source for photosynthesis. e. It allows for the breakdown of complex macromolecules.
The reason that an action potential is so brief is that
a. a wave of repolarization immediately follows the rising portion of the spike. b. the closing of potassium gates allows the voltage difference across the neural membrane to be restored. c. the channels for sodium movement remain open. d. the sodium-potassium pump restores the electrical gradients. e. the membrane limits electrical activity.
Which statement about the genetic code is false?
A. Some amino acids are specified by more than one codon. B. Every codon codes for one amino acid. C. The genetic code is almost universal, but not quite. D. Nucleotides are always read in groups of three. E. There is no punctuation or spacing between codons.