Touching a jellyfish can be a very painful experience whereas touching a comb jelly is not painful. Why is there a difference?
A. Nematocysts in ctenophores lack venom.
B. Ctenophores have very reduced nematocysts that cannot penetrate human skin.
C. Ctenphores do not possess nematocysts.
D. Ctenophores only use nematocycts for feeding, not for defense.
C. Ctenphores do not possess nematocysts.
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Natural or man-made substances released into soil, air, or water in greater than natural amounts are called:
a. acids b. pollutants c. nutrients d. metals e. chemicals
Repeated stimulation of a motor unit over a short period of time leads to
a. fatigue. b. tetanus. c. increased muscle strength. d. muscle twitch. e. increased ATP production.
Y-linked traits are ____
a. known as homozygous traits b. known to skip generations in males c. carried only by males and transmitted only to males d. carried only by females, but are never expressed e. passed on to only 50% of female progeny
In addition to a vertebral column, all vertebrates have
A. gills. B. scales. C. a distinctive head or skull. D. a tunic. E. an open circulatory system.