In placental mammals, how does the fetus obtain nutrients and oxygen?
A. Maternal veins and and fetal arteries are directly connected in the chorionic villi.
B. Maternal blood cells are carried across the fetal capillary walls through special pores.
C. Diffusion into the umbilical capillaries from maternal blood surrounding the chorionic villi.
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.
Answer: C
You might also like to view...
A microbiologist is working with two genera of bacteria, A and B, to determine if cells are competent. Strains are grown under optimal conditions, and DNA fragments that carry the gene for green fluorescent protein is added to each culture at 20-minute intervals. Samples from each treatment are plated to nutrient agar and incubated, after which the plates are examined under an ultraviolet lamp. The microbiologist observes that all plates of bacteria B contain colonies that are fluorescent, while for bacteria A only the plates from stationary phase demonstrate fluorescent colonies. What can be concluded from these results?
A. Competence in bacteria A is constitutively expressed. B. Competence in bacteria B is dependent on the phase of growth. C. Both bacteria A and bacteria B cells are competent. D. Neither bacteria A nor bacteria B cells are competent.
In the human endocrine system, the hormone prolactin is produced by the _____________________ and targets the _______________.
A. anterior pituitary; mammary glands B. anterior pituitary; pancreas C. posterior pituitary; kidneys D. posterior pituitary; mammary glands E. posterior pituitary; pancreas
In DNA fingerprinting, amplified fragments of DNA are separated from one another by which process?
A) filtering B) chromatography C) electrophoresis D) PCR (polymerase chain reaction)
Your younger brother has cut himself with a rusty knife he found in the garden. The wound is not life threatening, but it is deep enough that it makes you concerned. You would ________
A) take him to an ER B) make an appointment with his primary health care provider C) take him to a DO D) make an appointment with his physician