Sieve plates:
A. are modified cell walls that connect sieve
elements.
B. do not contain plasmodesmata.
C. dissolve at sieve tube maturity.
D. have solid, impermeable surfaces.
E. contain mitochondria and chloroplasts.
A
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You are performing an experiment to assay phosphorylation of a substrate by a protein kinase. Based on the data in the table below, what do these experimental results suggest?
A. GTP is not required for phosphorylation.
B. The substrate can undergo autophosphorylation.
C. The substrate is not required for phosphorylation.
D. The protein kinase is required for phosphorylation.
Allergies occur when the body responds to _____
a. pathogens c. normally harmless substances b. toxins d. all of these
Amniocentesis is not performed on mothers over the age of thirty-five
a. True b. False
Structures that are similar in different species and have a common ancestor are
A. analogous. B. related. C. revolutionary. D. homologous.