An unidentified cell was found to contain introns and exons. It also expresses DNA polymerase and RNA polymerase. Although it exhibits a promoter region, it has no operons. You conclude that this cell
A. is either a prokaryotic or eukaryotic cell.
B. is actually a virus.
C. is eukaryotic.
D. is prokaryotic.
Answer: C
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Figure 15.1 shows the three alleles for the beta-globin gene. Which of the following statements best describes the effect of having the S allele, which codes for sickle-cell anemia?
A. Having the allele is always harmful. B. Having the allele is always beneficial. C. The effect depends on whether the allele occurs in its homozygous or heterozygous form. D. The effect depends on the environment (i.e., whether malaria is present). E. The effect depends on whether the allele occurs in its homozygous or heterozygous form, and the environment (i.e., whether malaria is present).
Which of the following statements about the mouse is FALSE?
a. Its scientific name is Mus musculus. b. Females give birth to offspring about three weeks after mating. c. It has been used to disprove the "inheritance of acquired characters" hypothesis. d. Knockout mice are those that carry a lethal allele. e. Knockout mice are those that have a gene that is completely nonfunctional.
Which of the following statements is FALSE
about cowbirds? a. Their host relationship is similar to cuckoos. b. They are insect-eaters. c. Females can lay thirty eggs in a season. d. Cowbird hatchlings are recognized as imposters by host parents. e. They now parasitize at least fifteen species of native North American birds
Which structure transmits sound waves to the malleus in the middle ear?
A) Tympanic membrane B) Auditory membrane C) Vestibular membrane D) Cochlea E) Pinna