In placental mammals, how does the fetus obtain nutrients and oxygen?
A. Maternal veins and fetal arteries are directly connected in the chorionic villi.
B. Diffusion into the umbilical capillaries from maternal blood surrounding the chorionic villi.
C. Maternal blood cells are carried across the fetal capillary walls through special pores.
D. Maternal arteries and fetal veins are directly connected in the chorionic villi.
E. Diffusion into the umbilical cord from maternal blood surrounding the chorionic villi.
B. Diffusion into the umbilical capillaries from maternal blood surrounding the chorionic villi.
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Nonspecific cell responses depend on the actions of lymphocytes, natural killer cells, and dendritic
cells. ____________________ Indicate whether the statement is true or false.
One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?
A) deletion B) inversion C) translocation D) duplication
The onset of AIDS is often accompanied by
A. a positive HIV test. B. lung infections and other opportunistic infections. C. a steep drop in T cell numbers. D. macrophage infection. E. Kaposi's sarcoma.
An anaerobe thrives and reproduces best in.
A) a moist environment. B) an acidic medium. C) cool temperature. D) the absence of oxygen.