Biology: The Unity and Diversity of Life (Looseleaf)
15th Edition
ISBN: 9781337408417
Author: STARR
Publisher: CENGAGE L
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Chapter 42, Problem 4CT
If an embryo splits at the two-cell stage, each of the resulting identical twins will have its own placenta. If such a split occurs near the time of implantation, the identical twins may shale a placenta. By contrast, fraternal twins never share placenta. Explain this difference between the two types of twins.
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Suppose that in the near future, you are a prenatal care provider. In the most recent ultrasound checkup on the expecting mother, you unfortunately found that the fetus is suffering a neural tube defect in the form of anencephaly. Seeing as the mother is still in the 12th week of pregnancy or the 1st trimester, the pregnancy can still be terminated via medical means. How would you explain to the parents the situation they are in?
Which of the following statements does NOT correctly describe the events following fertilization?
Select one:
a. Only the inner cell mass cells in a blastocyst are pluripotent.
b. The trophoblast has an important role in maintaining the pregnancy, as it prevents the endometrium from shedding.
c. As hCG takes over maintaining the endometrium immediately after implantation, the corpus luteum degenerates into the corpus albican.
d. All 16 cells in a morula are truly totipotent, meaning that they can become any cells in the human body.
Describe the development of reproductive organs in a fetus of each gender. Which
genes, gene products, and hormones are involved in the sex differences? Which sex-
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compared to a nonpregnant woman? Do these hormones cross the placenta (if you
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fetal reproductive development?
Chapter 42 Solutions
Biology: The Unity and Diversity of Life (Looseleaf)
Ch. 42 - Prob. 1DAACh. 42 - Prob. 2DAACh. 42 - Prob. 3DAACh. 42 - Prob. 4DAACh. 42 - The end product of cleavage is a __________. a....Ch. 42 - The outermost germ layer in a vertebrate gastrula...Ch. 42 - Prob. 3SQCh. 42 - Prob. 4SQCh. 42 - In humans, fertilization typically occurs in the...Ch. 42 - The ________, a fluid-filled sac, surrounds and...
Ch. 42 - The placenta consists of __________. a. embryonic...Ch. 42 - During the fetal period, ____________. a....Ch. 42 - Prob. 9SQCh. 42 - Match each hormone with its action(s). ______...Ch. 42 - Prob. 11SQCh. 42 - Prob. 12SQCh. 42 - Prob. 13SQCh. 42 - Prob. 14SQCh. 42 - Place these events in human development in the...Ch. 42 - The rubella virus causes German measles. If a...Ch. 42 - A nursing mother who has an alcoholic drink...Ch. 42 - To determine the effect of the bicoid gene,...Ch. 42 - If an embryo splits at the two-cell stage, each of...
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- If cells choose to become trophoblast, they will end up in the placenta. If they choose to become ICM, they will give rise to the 3 germ layers that will make up the rest of the body of the embryo. Explain what rpocesses or mechanisms will guide them to make the right decision. Do they have a choice?arrow_forwardIdentify the labeled structures in the embryo shown:arrow_forwardIn cleavage states what is blastomeres, 2-cell stage, 4-cell stage, and 8-cell stage.arrow_forward
- During the first trimester, hCG produced from the chorion maintains the corpus luteum. What is the purpose of maintaining the corpus luteum? Select one: a. The corpus luteum produces relaxin, which thickens the endometrium. b. The corpus luteum ensures that the endometrium does not break down during the first trimester. c. The corpus luteum supports the formation of the placenta. d. The chorion forms the fetal part of the placenta, and the corpus luteum supports the maternal part of the placenta.arrow_forwardA friend in your dormitory, a freshman, tells you that she just discovered she is 3 months pregnant. You know that since she came to college she has been experimenting with recreational drugs. Circle the best advice you could give her, and explain your choice. (a) She must stop taking the drugs, but they could not have affected her fetus during these first few months of her pregnancy. (b) Harmful substances usually cannot pass from mother to embryo, so she can keep using drugs. (c) There could be defects in the fetus, so she should stop using drugs and visit a doctor as soon as possible. (d) If she has not taken any drugs in the last week, she is OK.arrow_forwardWhich of the following statement does NOT correctly describe the event of the following fertilization? Select one: A. As hCG takes over maintaining the endometrium immediately after implantation, the corpus luteum degenerates into the corpus albican. B. All 16 cells in a morula are truly totipotent, meaning that they can become any cells in the human body. C. The trophoblast has important in maintaining the pregnancy, as it prevents the endometrium from shedding. D. Only inner cells mass in a blastocyst is pluripotent.arrow_forward
- There are 6 major events in fertilization. Discuss the process of fertilization or conception, with emphasis on the sperm-egg interaction. Proteins on the sperm plasma membrane bind to ZP3 molecules within the zona pellucida of the egg. Why is this event important? Zona binding triggers the acrosome reaction, in which the sperm plasma membrane fuses with the outer acrosomal membrane, causing exocytosis of acrosomal contents. What is in the "acrosomal content"? Acrosomal enzymes begin to dissolve a hole in the zona pellucida. This enzymatic degradation, accompanied by rapid sperm tail beating, moves the sperm through the zona. Where does the sperm intend to reach?arrow_forwardDescribe how the following components relate to the placenta: umbilical arteriescotyledons, fetal vessels,chorionic villi, intervillous space, spiral arterioles, and umbilical vein?arrow_forwardName and describe each of the three stages of prenatal development. Then go on to explain the possible impact of teratogens at each stage. Specifically, look at what structures are most likely to be impacted at each stage.arrow_forward
- a) Describe the process of neuralation. b) Identify the germ layer from which the nervous system forms. c) Describe when in development neuralation occurs. d) Identify a teratogen that could affect the development of the brain during this stage of pregnancy.arrow_forwardSometimes a sperm cell fertilizes a polar body rather than a secondary oocyte. An embryo does not develop, and the fertilized polar body degenerates. Why is a polar body unable to support development of an embryo?arrow_forwardwhat is the process which involves in the self-destruction of cells in the developing embryo as shown in the disappearance of the embryo’s tail?arrow_forward
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Embryology | Fertilization, Cleavage, Blastulation; Author: Ninja Nerd;https://www.youtube.com/watch?v=8-KF0rnhKTU;License: Standard YouTube License, CC-BY