In Meselson and Stahl's experiment, what kind of DNA molecules would be found after four replication cycles?
A) Only heavy DNA (15N-15N)
B) Only intermediate DNA (15N-14N)
C) Only light DNA (14N-14N)
D) Both heavy (15N-15N) and light DNA (14N-14N)
E) Both heavy (15N-15N) and intermediate DNA (15N-14N)
D
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In insects, primary symbionts are ________, while secondary symbionts ________
A) heritable / are transmitted horizontally B) able to replicate outside of the host / are obligate symbionts C) required for host reproduction / are not required for host reproduction D) obligate symbionts / have a free-living replicative stage
Like the insects, the arachnids (spiders and so on) have
(a) three pairs of walking legs. (b) one pair of antennae. (c) true mandibles. (d) an abdomen.
Which statement best describes parasitism?
a. A parasite is harmful to the host. b. A parasite provides nutrients for the host. c. A parasite does not harm the host. d. A parasite does not receive any benefits from the host. e. A parasite always kills its host.
Shown below is a diagram for a plasmid vector you want to use to clone a gene. The diagram shows the location of the recognition sites for four restrictions enzymes, BamHI (B), EcoRI (E), HindIII (H), and XhoI (X). The genes encoding beta-lactamase (AmpR) and beta-galactosidase (lacZ) are indicated. If you were to use this vector, which enzyme should be used to linearize the plasmid in preparation for cloning?
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A. XhoI B. EcoRI C. BamHI D. HindIII E. EcoRI and XhoI