Suberin is a waxy substance that is typically associated with the
a. primary xylem.
b. root hairs.
c. endodermis.
d. tonoplasts.
e. pericycle.
C
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Each of the following is correct about cholera and its effect on G-protein–adenylyl cyclase activity except
A) Vibrio cholera bacteria colonize the gut. B) Cholera toxin is secreted by Vibrio cholera bacteria. C) Intestinal cells infected with cholera toxin import abnormally high levels of salts and fluids into the bloodstream. D) Cholera toxin alters Gs? so that it no longer hydrolyzes GTP. E) Intestinal cells infected with cholera toxin maintain abnormally high cAMP levels.
During meiosis, a defect occurs in a cell that results in the failure of microtubules, spindle fibers, to bind at the kinetochores, a protein structure on chromatids where the spindle fibers attach during cell division to pull sister chromatids apart
. Which of the following is the most likely result of such a defect? A) New microtubules with more effective binding capabilities to kinetochores will be synthesized to compensate for the defect. B) Excessive cell divisions will occur resulting in cancerous tumors and an increase in the chromosome numbers known as polyploidy. C) The defect will be bypassed in order to and ensure normal chromosome distribution in the new cells. D) The resulting cells will not receive the correct number of chromosomes in the gametes, a condition known as aneuploidy.
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.
After the completion of meiosis in humans, a diploid germ cell has produced cells with half the original chromosome number, generating __________ haploid nuclei.
a)2 b)3 c)4 d)23 e)46