The placenta ____
a. forms from endometrial and extraembryonic tissues
b. will cover about one-half of the inner uterine surface at full term
c. intermingles fetal blood with maternal blood
d. secretes only estrogen to maintain the uterine lining during the second and third trimesters
e. secretes only progesterone to maintain the uterine lining during the second and third trimesters
ANSWER: a
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Which of the following is the strongest evidence that cytokinins regulate cell divisions? There is _____
A) an increase of cyclin gene expression in tissues exposed to cytokinin B) a decrease of cyclin gene expression in tissues exposed to cytokinin C) an induction of shoot growths in tissues exposed to cytokinin D) an induction of root growths in tissues exposed to cytokinin E) an ability of cytokinin to interact with auxin at the molecular level and change auxin biosynthesis and transport
Recombinant DNA is any DNA that ____
a. has been cut by restriction enzymes b. is at least four to eight base pairs in length c. has had its gene sequence rearranged d. consists of DNA from two or more organisms of the same or different species e. inserted into plasmids
What results when a population grows larger than the carrying capacity?
A) Food becomes abundant. B) Birth rates remain stable. C) Death rates rise. D) The carrying capacity increases.
A hemocoel or blood cavity is found in or associated with
A) all animals. B) sponges. C) an open circulatory system. D) acoelomates. E) cephalopods.