In phloem movement, which of the following does not serve as a source?
a. photosynthesizing cells in a leaf
b. roots
c. photosynthesizing cells in a stem
d. food storage cells in a stem
e. soil
E
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What do enzyme-linked receptors and growth factor receptors have in common?
A. Both possess kinase activity when bound to a hormone. B. Both regulate specific G proteins when bound to a hormone. C. Both act as transcriptional factors. D. Both regulate the transport of ions through channels. E. Both seldom affect the expression of genes within the nucleus.
How does a phage transfer DNA from one bacterium to another?
a. Phages form a bridge between bacterial cells that allows DNA to pass from the host cell to the recipient cell. b. Phages form a bridge between bacterial cells that allows DNA to pass in both directions between the two cells. c. Phages lyse bacterial cells, releasing bacterial DNA into the environment, which is taken up by other phages for transfer to new cells. d. When phages assemble in an infected bacterial cell, they may incorporate host DNA; released phages may attach to other cells and inject the bacterial DNA into those cells. e. Phages attach to receptors on bacterial cells and receive some of the target cells’ DNA; the phages release this DNA into the environment to be taken up by other bacterial cells.
Hemicellulose contains chains of xylose molecules
____________________ Indicate whether the statement is true or false.
Which of the following makes epigenetics difficult to study
a. It does not depend on the nucleotide sequence of the DNA. b. It is hard to sequence the entire human genome. c. It is not heritable. d. DNA sequences mutate too quickly to track changes.