Humans belong to the phylum ________.
A. chordates
B. echinoderms
C. arthropods
D. mollusks
Answer: A
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In male White-Crowned Sparrows, the sensitive period for song learning is:
A. the time during which they produce their subsong—between 50 days after hatching and about 250 days after hatching. B. the time between about 250 and 300 days after hatching, when they are producing an imperfect version of their father's song. C. about 10–50 days after hatching, when they must hear adult male song if they are later to be able to sing a proper adult male song of their own. D. the time during which, if they are presented with a live tutor of a closely related species, they can learn the other species' song instead of their own. E. the time during which, if they are presented with tapes of their own species' song and the song of a closely related species, they can learn the songs of both species.
Which of the following sequence of events of fertilization is in the proper order?
A. acrosomal reaction, binding of sperm to egg membrane, fast block to polyspermy, increase in egg cytosolic calcium, and then the slow block to polyspermy B. binding of sperm to egg membrane, acrosomal reaction, fast block to polyspermy, slow block to polyspermy, and then an increase in egg cytosolic calcium C. binding of sperm to egg membrane, acrosomal reaction, fast block to polyspermy, increase in egg cytosolic calcium, and then the slow block to polyspermy D. acrosomal reaction, fast block to polyspermy, binding of sperm to egg membrane, increase in egg cytosolic calcium, and then the slow block to polyspermy E. acrosomal reaction, fast block to polyspermy, binding of sperm to egg membrane, slow block to polyspermy, and then an increase in egg cytosolic calcium
Rockweeds overcome the problems of desiccation by:
a. growing only in shaded areas. b. having a gelatinous covering. c. evaporating water from their tissues. d. bending with the waves. e. being covered with a waxy cuticle.
How does cooperative binding work?
a. Hemoglobin molecules form clumps and accumulate extra oxygen in the pile-up. b. Conformational changes in red blood cells allow for additional oxygen molecules once one is picked up. c. Hemoglobin is more likely to bind to oxygen once one O2 is bound. d. When O2 is bound to hemoglobin, a CO2 molecule can also bind to hemoglobin