The small portion of the embryo that will become its dorsal side develops from the
A) morula.
B) primitive streak.
C) archenteron.
D) gray crescent.
E) blastocoel.
Answer: D) gray crescent.
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Some of the olfactory receptor (OR) genes in humans
A. have been inactivated, reducing our olfactory capabilities compared to other primates. B. have been activated, enhancing our olfactory sense compared to other primates. C. have duplicated more frequently, resulting in increased paralogs compared to other primates. D. have been conserved more rigidly, resulting in increased orthologs compared to other primates.
Fuels used in cars, and the carbon dioxide cars emit, were originally carbon dioxide
A. fixed by vascular and nonvascular plants during photosynthesis about 300 mya. B. fixed in the tissues, decayed from dinosaurs after the Cretaceous mass extinction. C. released from volcanoes, and accumulated over centuries. D. trapped in rocks and compressed into oil and coal, during the Precambrian. E. trapped in the ocean and secreted into large coral reef structures, during the Mesozoic.
What are two factors affect membrane fluidity?
What will be an ideal response?
The chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and __________________________
(a) occupy discrete territories in the nucleus. (b) share the same nuclear territory as their homolog. (c) are restricted to the nucleolus. (d) are completely tangled with other chromosomes.