The force of blood flowing through the __________ keeps it firm.
A) amnion
B) umbilical cord
C) yolk sac
D) embryonic disk
Question 2The placenta __________.
A) forms in the second trimester of pregnancy
B) encloses the developing organism in amniotic fluid
C) contains one large vein that delivers nutrients to the embryo
D) delivers food and oxygen to the developing organism
Question 3The yolk sac __________.
A) forms during the third trimester of pregnancy
B) is the outer ring of cells that surrounds the blastocyst
C) produces blood cells until the organs are mature enough to take over this function
D) contains one large vein that delivers blood loaded with nutrients and two arteries that remove waste
Question 4The amniotic fluid __________.
A) delivers food and oxygen to the developing organism
B) helps keep the temperature of the prenatal world constant
C) delivers nutrients and removes waste products
D) produces blood cells until the organs are mature enough to take over this function
Question 5When the blastocyst burrows deep into the uterine lining, __________.
A) implantation occurs
B) pregnancy does not occur
C) it stops growing
D) the cells of the zygote first duplicate
Question 6Which statement about a blastocyst is true?
A) It consists of a single cell.
B) It is a structure that feeds the developing organism.
C) Between the seventh and ninth days, it burrows deep into the uterine lining.
D) It is a membrane that helps to keep the temperature of the prenatal world constant.
Question 7Irina is in her first week of pregnancy. During this time, __________.
A) heart muscles begin to develop
B) the zygote multiplies and forms a blastocyst
C) a primitive brain and spinal cord appear
D) the embryo can move
Question 8The embryonic disk __________.
A) becomes the new organism
B) is the outer ring of cells on a blastocyst
C) has a good chance of survival outside the womb
D) is a protective membrane that surrounds the amnion
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