Leeches and earthworms belong to the phylum containing the
A. annelids.
B. nematodes.
C. sponges.
D. flatworms.
E. mollusks.
A. annelids.
You might also like to view...
Chemosynthetic organisms use the energy from ____ to produce organic molecules
a. the sun b. chemical reactions c. the water d. other organisms. e. glucose
A pile of castings outside the burrow of a polychaete indicates it
a. has just dug a burrow. b. has completed a meal of other worms. c. is a filter feeder. d. is a selective deposit feeder. e. is a nonselective deposit feeder.
Correct and appropriate signal transduction processes are generally under strong selective pressure and are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities
between signal and receptor. Therefore, a hormone action is very specific in a species at any one point in time. However, there are examples of very diverse functions of a specific hormone between groups of organisms. For example, thyroxin, which is produced in all vertebrates and many invertebrates, can trigger growth, differentiation, metamorphosis, maturation, reproduction, behavior, temperature tolerance, osmoregulation, or seasonal adaptation depending on the organism in which it is produced. What is the most logical explanation for such different responses triggered by thyroxin in organisms? A) The concentration of thyroxin varies in different organisms. Invertebrate organisms do not have as much thyroxin as vertebrate organisms. B) Thyroxin and its receptor molecules have a different binding affinity in different organisms. C) Receptor molecules for thyroxin are located on different tissues in different organisms. D) The structure of thyroxin is substantially different in different organisms.
Consider an organism whose karyotype shows it to have a total of 60 chromosomes. How many chromosomes would be contained in the sperm of this organism?
A. 90 B. 46 C. 23 D. 30 E. 60