Scientists believe that the heart of the common (chordate) ancestor of all vertebrates
A. consisted of a single ventricle.
B. had four chambers.
C. had two chambers.
D. had three chambers.
E. was little more than a heavily-muscled region of the ventral artery.
E. was little more than a heavily-muscled region of the ventral artery.
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On what basis have Microsporidia been classified as fungi?
A. Lack of mitochondria B. Analysis of ribosomal RNA C. Presence of a polar tube D. Presence of mitosomes E. Role as an obligate intracellular parasite
Genes that tend to be inherited together are said to be:
a. associated. b. related. c. similar. d. linked. e. alleles.
Maria has been in labor for 12 hours, and her obstetrician thinks that it is time to artificially induce birth. What hormone will the physician inject?
A) estrogen B) vasopressin C) prolactin D) oxytocin
What do seeds contain?
A. embryo and nutritive tissue B. male gametophyte and nutritive tissue C. female gametophyte and nutritive tissue D. mature sporophyte and nutritive tissue