Geologists have evidence that over the past 1.5 billion years
A) Earth's landmasses have remained in the same shape and positions as they have in the current time.
B) Earth's landmasses have joined into a single continent and split back apart again on three occasions.
C) Earth's landmasses have changed positions extensively but have remained separate and in the same shapes.
D) Earth's landmasses have changed shape and have been entirely submerged in water on three occasions.
Answer: B
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You are working in a lab and come across a gene, Gene X, that you think might explain some of the differences seen between chimpanzees and humans. Which of the following results would support your hypothesis?
A. if Gene X was active in humans, juvenile chimpanzees and inactive in adult chimpanzees B. if Gene X was active in humans, adult chimpanzees and inactive in juvenile chimpanzees C. if Gene X was active in adult humans and adult chimpanzees but inactive in juvenile humans D. if Gene X was active in juvenile humans, juvenile chimpanzees, and adult chimpanzees but inactive in adult humans
The equivalent in figure 2 of letter “D” in figure 1 is
indicated by a. E. b. F. c. G. d. H. e. all of these.
Which statement best describes the difference between passive immunity and active immunity?
A) Active immunity refers to T lymphocytes actively destroying pathogens through phagocytosis and passive immunity describes the indirect attack by B lymphocytes through secretion of antibodies. B) Active immunity fight viruses such as rabies by injecting antibodies collected from that animal whereas passive immunity is injecting antibodies from a safe form of the pathogen. C) Active immunity depends on injecting antibodies into the body whereas passive immunity includes vaccination or immunization of a safe form of a pathogen. D) Active immunity depends on the ability of a person's immune system to mount a response to a pathogen and induces immunological memory, whereas in passive immunity only antibodies are introduced to the body allowing only for short-term protection. E) Active immunity is only active for a short time frame in the body whereas passive immunity has long-lasting immunity in the body
Which situation(s) might warrant the removal of a histidine tag when purifying a recombinant protein?
A. The expression vector used for inserting the gene of interest already contains histidine-encoding sequences. B. Histidine residues inhibit protein folding, thereby decreasing the functionality of the protein. C. Histidine residues bind preferentially to nickel resins on the column during purification, and are not washed away. D. All of the choices are correct.