Below is a molecule of caffeine. Which of the following features are not present in a molecule of caffeine?
A) a carbonyl group
B) a carboxyl group
C) a methyl group
D) a double bond
Answer: B
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Which of the following summarizes the Hardy-Weinberg principle?
a. Without evolutionary forces, a population’s allele frequencies are stable. b. Traits are acquired through use or disuse and passed to offspring. c. Due to microevolution, the population’s genetic structure is changing. d. Natural selection impacts the genetic makeup of a population.
During prophase, ____ is(are) compacted into visible chromosomes
a. chromatin b. centrioles c. centromeres d. kinetochores e. tetrads
You are interpreting data on a DNA chip or microarray. You expose the chip to a mixture of two cDNA populations: one from cells that were not treated with a glucocorticoid hormone (untreated controls; labeled with a red fluorescent dye) and one from cells that were treated with glucocorticoid hormones (glucocorticoid-treated; labeled with green fluorescent dye). You look at a spot on the chip representing the gene for glutamyltransferase and it is green. How do you interpret this result?
a) The glutamyltransferase gene is expressed in the control cDNA population, but not in the glucocorticoid-treated population. b) The glutamyltransferase gene is expressed essentially equally in both cDNA populations. c) The glutamyltransferase gene is not expressed in the control cDNA population, but it is expressed in the glucocorticoid-treated population. d) The glutamyltransferase gene is not affected by glucocorticoid treatment.
In a method called patch-clamping, a glass capillary can be converted into a microelectrode that measures the electrical currents across biological membranes. Which of the following is not true about the patch-clamp method?
(a) The glass capillary adheres to a "patch" of membrane through the application of suction. (b) The aperture in the glass capillary used to make a microelectrode is about 1 ?m in diameter. (c) If the experimental conditions are held constant, fluctuations in electrical currents across the patch of membrane are still observed. (d) Single-channel patch-clamp recordings have demonstrated that gated membrane channels will only open and close in response to specific stimuli. Ion Channels and Signaling in Nerve Cells