The blood vessels of the umbilical cord are formed by which extraembryonic membrane?
a. yolk sac
b. chorion
c. allantois
d. amnion
e. placenta
c
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For water to vaporize
A. energy must be supplied. B. energy must be released. C. hydrogen bonds are broken. D. both energy must be supplied and hydrogen bonds broken. E. both energy must be released and hydrogen bonds broken.
Which of the following statements about Hfr cells and bacterial conjugation is false?
A. An Hfr cell becomes an F- cell if its integrated F plasmid is excised. B. If excision of the F plasmid from an Hfr cell includes some bacterial genes, a partial diploid can result. C. The genes that are transferred from an Hfr cell into a recipient cell during conjugation replace the equivalent genes in the recipient cell. D. An F' plasmid contains some bacterial genes. E. Cells with integrated F' plasmid have two copies of some genes.
In this exercise, how should bacterial colonies on your plate that are not S. marcescenes be recorded on the data sheet?
A) (+) B) (-)
The atomic number of an element is ________
a. the sum of its photons and electrons b. the number of protons c. the sum of its protons, neutrons, and electrons d. the number of electrons