Characterize phloem
What will be an ideal response?
Phloem is composed of living cells: the sieve tube members with their small companion cell. The sieve tube members are indeed alive, but they lack a functioning nucleus; the companion cell does have a functioning nucleus, and directs the activities of the adjacent cell. At the ends of the sieve tube members are sieve plates with large pores that let fluids and dissolved materials easily pass from cell to cell. Flow in the phloem is from the source (the photosynthetic parts of the plant) to the sink (cells that are not photosynthetic),
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The ribonucleoprotein, RNase P, catalyzes the:
A. exonucleolytic removal of the 3' end of tRNA molecules. B. endonucleolytic removal of the 5' end of tRNA molecules. C. ATP-independent removal of tRNA introns. D. degradation of the poly(A) tail.
Clostridium botulinum toxin is
A. heat-stable. B. an exotoxin. C. endotoxin. D. heat-sensitive. E. an exotoxin AND heat-sensitive.
If genes are linked and an F1 is testcrossed,
A) the genes cannot separate. B) they can produce only one phenotype. C) they only produce homozygotes. D) they produce more recombinant phenotypes than parental phenotypes. E) they produce more parental phenotypes than recombinant phenotypes.
What facilitate the rapid transport of water through the plasma membrane?
a. osmosis b. uniporters c. aquaporins d. channel proteins e. ABC transporters