What is the function of sex pili in prokaryotes?
a. biofilm formation
b. transfer of DNA
c. protein polymerization
d. energy production
e. lipid synthesis
ANSWER: b
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A graduate student wants to clone a particular gene into a plasmid. The sequence includes AluI and BamHI sites on both sides of the desired fragment
AluI cuts symmetrically directly between the G and C nucleotides in a palindromic 5' AGCT 3' sequence. BamHI cuts asymmetrically directly between the G and G nucleotides in a palindromic5' GGATCC 3' sequence. Which of the two restriction endonucleases should the graduate student choose, and why? A. BamHI to cut both sides-since it cuts asymmetrically, it'll leave the sticky, cohesive single-strand DNA ends that will make it easier to ligate into a BamHI-cut plasmid DNA sequence. B. AluI to cut both sides-it's always easier to ligate together blunt ends of DNA. She should also use AluI on the plasmid she wants to put the fragment into. C. BamHI on the fragment, and AluI on the plasmid-this will give her the matching sequences to anneal/ligate together on the fragment/plasmid combination. D. BamHI on one side of the fragment, and AluI on the other side-this would keep the fragment from sticking right back to where it was cut out from in the original DNA.
Where are the fungal hyphae in a mycorrhiza?
a. the space between the cell wall and the plasma membrane of root cells. b. in the cytoplasm of root cells. c. on the surface of plant stems, above ground. d. within the vasculature of the leaves of a plant. e. on the outside of the cell wall of root cells.
The cortical reaction prevents multiple sperm from contributing their chromosomes to the egg.
Answer the following statement true (T) or false (F)
The nematode Caenorhabditis elegans is important to human medicine because it
A. causes elephantiasis, a disease of the lymph glands that causes the legs of humans to swell. B. is transmitted by mosquitoes and causes high fevers. C. is an intestinal parasite in human digestive tracts. D. has easily observed development and has a short generation time.