The hypothesis that high pressure forces phloem sap to flow was tested and supported by studies using
a. caterpillars.
b. radiolabeled hormones.
c. vacuum chambers.
d. aphids.
e. radiolabeled sugars.
D
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Which of the following plant structures shares the most common features and functions with a fungal hyphae?
A) stomata B) vascular cambium C) lenticels D) root hairs E) prop roots
The adenylation of DNA ligase is:
A. an unstable initial step in the reaction. B. occurs at a lysine residue in the DNA binding domain. C. dependent on the presence of DNA. D. independent of the presence of DNA. E. more efficient at lower pH.
Four of the following are extraembryonic membranes of the amniote egg. Which one is the exception?
a. albumen b. amnion c. chorion d. allantois e. yolk sac
Semen contains
a. sperm. b. the secretions of sex accessory glands. c. eggs. d. both a and b.