A) Unlike frogs,sea urchins are deuterostomes,which form the anus first and the mouth second.
B) Sea urchin cells migrate inside to form the archenteron,whereas in frogs proliferation of dividing cells from the dorsal lip populate the inside of the embryo.
C) Sea urchins have relatively yolk-poor eggs with similar animal and vegetal poles,whereas frogs have large amounts of yolk distinguishing the vegetal pole from the animal pole.
D) Frogs have an animal pole and vegetal pole,whereas urchins have only a vegetal pole.
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A) Male infertility due to inability of the sperm to tunnel through the blastula.
B) Male infertility due to inability of the sperm to tunnel through the zona pellucida.
C) Female infertility due to blockage of sperm from tunneling through the allantois.
D) Female infertility due to blockage of sperm from tunneling through the archenteron.
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A) Inability to retain the fluid that surrounds the embryo
B) Inability to form the placenta
C) Problems with gas exchange
D) Loss of nutritional stores
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A) They are histone proteins.
B) They are small peptides.
C) They are from maternal mRNAs.
D) They are from paternal mRNAs.
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A) fertilization
B) cleavage
C) gastrulation
D) organogenesis
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A) Sea cucumbers appear not to block polyspermy the same way as sea urchins,which use an influx of Na+ that changes the membrane potential.
B) Sea cucumbers appear not to block polyspermy the same way as sea urchins,which use an outflow of Na+ that changes the membrane potential.
C) Sea cucumbers appear to block polyspermy the same way as sea urchins,via an influx of Na+ that changes the membrane potential.
D) Sea cucumbers appear to block polyspermy the same way as sea urchins,via an outflow of Na+ that changes the membrane potential.
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A) zona pellucida
B) acrosome
C) granulosa
D) blastula
E) neural cap
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A) Signaling molecules from the organizer inhibit ventral development.
B) The dorsal lip cells directly activate dorsal development.
C) The organizer determines the dorsal-ventral axis.
D) The organizer forms in the area of the grey crescent.
E) The point of sperm entry determines the orientation of the organizer.
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A) Too little endoderm,resulting in missing gut and organs
B) Too little ectoderm,resulting in missing nervous system or skin
C) Problems in muscle development
D) Too little protoderm,resulting in missing organs
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