Biology

Cell differentiation always involves A) the production of tissue-specific protei

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The functioning of enhancers is an example of A) transcriptional control of gene

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Muscle cells differ from nerve cells mainly because they A) express different ge

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If a particular operon encodes enzymes for making an essential amino acid and is

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Embryonic lethal mutations result in A) phenotypes that prevent fertilization. B

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What is considered to be the first evidence of differentiation in the cells of a

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In animals, embryonic stem cells differ from adult stem cells in that A) embryon

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A mutation that inactivates the regulatory gene of a repressible operon in an E.

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The lactose operon is likely to be transcribed when A) there is more glucose in

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Transcription of the structural genes in an inducible operon A) occurs continuou

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For a repressible operon to be transcribed, which of the following must occur?

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Steroid hormones produce their effects in cells by A) activating key enzymes in

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Transcription factors in eukaryotes usually have DNA binding domains as well as

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Gene expression might be altered at the level of post-transcriptional processing

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In humans, the embryonic and fetal forms of hemoglobin have a higher affinity fo

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The fact that plants can be cloned from somatic cells demonstrates that A) diffe

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If a bacterium regenerates from an endospore that did not possess any of the pla

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The major evolutionary episode corresponding most closely in time with the forma

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If two continents converge and are united, then the collision should cause A) a

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Which of the following statements provides the strongest evidence that prokaryot

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An early consequence of the release of oxygen gas by plant and bacterial photosy

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If a fossil is encased in a stratum of sedimentary rock without any strata of ig

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What is true of the fossil record of mammalian origins? A) It is a good example

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Which measurement(s) would help determine absolute dates by radiometric means? A

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) If the half-life of carbon-14 is about 5,730 years, then a fossil that has one

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