How much nitrogen is fixed by free-living organisms in soils relative to symbionts?
a. 100x
b. 10x
c. 1%
d. 10%
d. 10%
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Transposable elements make up about 75% of the DNA in the human genome
A. true B. false
T cells attack
A. transplanted tissue cells from one host to another. B. cancer cells. C. host cells that have been parasitized by microorganisms. D. All of the choices are correct.
The best possible analogy available below for the way in which variable (V), diversity (D), and joining (J) antibody gene segments get put together to create the diversity possible in hypervariable regions is
A. to think of the various segments as a deck of cards-when you get dealt a hand of five cards, you have a very high likelihood of getting a diferent hand every time. The quality of the hand you have dealt will dictate whether you have a "winning" hand (capable of binding to antigenic epitopes). B. to think of the various segments as the pieces of a house-you need a strong foundation first (the joining segments), followed by a frame (the diversity segments), then the interior walls (the variable segments) before the structure is complete. C. to think of the various segments as building a highway-you need to prepare the area first by clearing a path (the joining segments do this), then grade/slope the area (the diversity segments) before you can finally lay down the asphalt (the variable segments). D. to think of the various segments as a bingo game-each segment is randomly selected, but you're going to need one of each V, D, and J to form a functional molecule. The "right" combination varaies depending on which antigen is eventually going to be binding to the molecule (i.e., your bingo card would be the eventual antigen, and the random calling out of the number/letter combinations would be the forming of the VDJ hypervariable region).
Which molecules are involved in the anchoring of cells to an extracellular matrix?
a. Interleukins b. angiostatin c. cyclins d. integrins