Which of the following statements regarding dynamic instability is false?
(a) Each microtubule filament grows and shrinks independently of its neighbors.
(b) The GTP cap helps protect a growing microtubule from depolymerization.
(c) GTP hydrolysis by the tubulin dimer promotes microtubule shrinking.
(d) The newly freed tubulin dimers from a shrinking microtubule can be immediately captured by growing microtubules and added to their plus end.
Choice (d) is untrue. A newly dissociated tubulin dimer will be bound to GDP; this GDP will need to be exchanged for GTP before it can be added to a newly growing microtubule.
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Each of the major hypotheses proposed to explain why sexual reproduction is more widespread than asexual reproduction ultimately base their explanations on the adaptive benefit of (select all correct choices):
A. forming pair bonds. B. forming genetically distinct offspring. C. forming large populations. D. forming relatively slow-growing populations. E. reducing mutation rates.
Why are sex chromosome aneuploidies less detrimental than autosomal aneuploidies?
A. Sex chromosomes do not contain genes that are important for anything other than sex determination. B. In females, all but one X-chromosome is inactivated; in males, the Y chromosome contains very few genes, so extra or missing copies do not cause huge abnormalities. C. Gene expression of the sex chromosomes is not dosage-dependent as it is for the autosomes. D. Sex chromosomes are only found in gametes, they do not occur in diploid cells. E. All of these are TRUE.
Acheulian tools, e.g., hand axes, choppers, borers, and scrapers, are associated with which group of hominins?
a. Homo sapiens b. Homo habilis c. Homo erectus d. Australopithecus sediba e. Australopithecus africanus
Species in widely separated but similar biomes often appear to display similar characteristics because of
A) convergent evolution. B) coevolution. C) mutations. D) evolutionary drift.