Which of the following are protein filaments that function in muscle contraction and are shaped like a golf club with two heads?
A) intermediate filaments
B) myosin filaments
C) myofilaments
D) actin filaments
B
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Four of the five items listed below are related
to genetic information. Select the EXCEPTION.
a. chromatids b. centromere c. chromosome d. phosphorylation e. polymerase
More than half a century ago, two cell biologists published details of their research involving isolated membrane vesicles from chloroplasts. Normally, the fluid inside these vesicles is near neutral
In an experiment, these membrane vesicles were soaked in an acidic solution (pH 4 ) until the inside of the vesicle also became pH 4. Based on the details provided in this scenario, by what mechanism could hydrogen ions have crossed the vesicle membrane, and what do you think happened at the molecular level? A) Active transport; hydrogen ions moved out of the vesicle with the help of ATP energy. B) Pinocytosis; water moved from outside the vesicle to inside. C) Facilitated diffusion; hydrogen ions moved into the vesicle through a channel protein. D) Simple diffusion; hydrogen ions moved into the vesicle through a channel protein. E) Osmosis; water moved from inside the vesicle to outside.
What would result if a leech had a mutation causing it to secrete low levels of anticoagulants?
A. The pain of the leech bite would cause the leech to be detected. B. The blood would stop flowing after a short time. C. The leech would have a hard time remaining attached to its host. D. The leech would have a hard time locating appropriate hosts.
Fortunately, the difference-in-differences estimate of a treatment effect also can be reported/interpreted as:
A. the coefficient on an interaction term. B. the ratio of t-stats. C. the second stage estimates of two-stage least squares. D. a simple difference in mean outcomes.