Campbell Biology
12th Edition
ISBN: 9780135188743
Author: Urry
Publisher: PEARSON
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Chapter 47, Problem 13TYU
SYNTHESIZE YOUR KNOWLEDGE
Occasionally, two-headed animals such as this turtle are born. Thinking about the occurrence of identical twins and the property of totipotency, explain how this might happen.
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Ken Doll isn't very smart. He and Barbie are not trying to have a baby. Ken is confused about a few details and asked his friend GI Joe why Barbie became pregnant. "Look, we did the deed on Monday and she didn't ovulate until Thursday. I should have been safe and my 'little swimmers' should have been out of there by then." How should GI Joe explain the necessary information to Ken?
A:
Why do sea urchins have external fertilization? [Discuss the life style of the developing sea urchin embryo in the water column compared to a very different ecological niche of the adults on the ocean floor. Besides, would you want to give live birth to a sea urchin! ouch!]
2:
Then why don't the parents take care of the young? [In fact the adults do in a way. After the embryo has grown large enough and metamorphosed into a young urchin they hide in the spines of the adults, living off of the scraps of food produced from the messy eating of the adults]
3:
Because the urchin life involves two or more ecological niches, they are more susceptible to predation and exposure to environmental toxins. What environmental conditions, predators and toxins might they be exposed to at each stage?
The slow block to polyspermy involves a permanent modification of the egg surface, usually through exocytosis of the cortical granules. In the 1970s, Dave Epel carried out experiments that led to the conclusion that a Ca2+ rise in the egg is both necessary and sufficient to trigger cortical granule exoctyosis (CGE). For the experiment below, describe it as correlation, loss-of-function or gain-of function. Then, indicate the predicted result.
Experiment (a) – Dr. Epel injects the egg with an indicator dye that fluoresces when Ca2+ binds to it. In unfertilized eggs, there is no fluorescence and no CGE. However, when sperm are added to the eggs, he observes fluorescence and then CGE.
Chapter 47 Solutions
Campbell Biology
Ch. 47.1 - How does the fertilization envelope form in sea...Ch. 47.1 - Prob. 2CCCh. 47.1 - MAKE CONNECTIONS Review Figure 12.16 on cell...Ch. 47.2 - In the frog embryo, convergent extension elongates...Ch. 47.2 - WHAT IF? Predict what would happen if Ca2+ was...Ch. 47.2 - MAKE CONNECTIONS Unlike some other types of birth...Ch. 47.3 - Prob. 1CCCh. 47.3 - Prob. 2CCCh. 47.3 - Prob. 3CCCh. 47.3 - Prob. 4CC
Ch. 47 - What cell-surface event would likely fail if a...Ch. 47 - What are some functions of apoptosis in...Ch. 47 - Suppose you found two classes of mouse mutations,...Ch. 47 - Prob. 1TYUCh. 47 - Which of the following is common to the...Ch. 47 - The archenteron develops into a. the mesoderm. b....Ch. 47 - What structural adaptation in chickens allows them...Ch. 47 - Prob. 5TYUCh. 47 - In humans, identical twins are possible because a....Ch. 47 - Cells transplanted from the neural tube of a frog...Ch. 47 - DRAW IT Each blue circle in the figure below...Ch. 47 - EVOLUTION CONNECTION Evolution in insects and...Ch. 47 - Prob. 10TYUCh. 47 - Prob. 11TYUCh. 47 - Prob. 12TYUCh. 47 - SYNTHESIZE YOUR KNOWLEDGE Occasionally, two-headed...
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- Infertility strikes both men and women. Describe in a summary the biological causes that impair the process of conception in both males and females. Besides mentioning specific reasons of infertility in males and females, you need to include in your answer other cause(s) that might be the result of a combination of factors originating from both men and women.arrow_forwardBoth men and women produce testosterone, but concentrations of testosterone in the blood are generally higher in men than in women. However, the testosterone levels of some XX females fall within the range of testosterone levels of XY men. This overlap has created controversy within women’s sports. Testosterone is known to increase muscle mass and enhance some types of athletic performance, so some people have suggested that women with naturally high testosterone levels have an unfair competitive advantage. In 2011, the International Association of Athletics Federations (IAAF) adopted a policy that limits levels of testosterone in female athletes, saying that female athletes must not have a blood testosterone concentration greater than 10 nanomoles per liter (nmol/L), a level typically seen in men. Some elite female athletes have natural testosterone levels above this limit and have challenged the policy. Do you think that it is fair for XX females with naturally high testosterone…arrow_forwardThere 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_forward
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- Occasionally, two-headed animals such as this turtle are born.Thinking about the occurrence of identical twins and the property of totipotency, explain how this might happen.arrow_forwardThe change of successful fertilization is approximately 18% in every cycle. Why does this statistic seem so low? All of the following statements provide a reason as to why the chance of fertilization is 18% every ovarian cycle EXEPT Select one: A. Some Sperm cells are not very motile, while others are formed without a tail. B. If more than one sperm fertilizes an egg, multiple embryos can result. C. Vagina is very acidic, killing many sperm. D. There two fallopian tubes and two ovaries, but only one of them releases an ovum every cycle.arrow_forwardSome couple practice natural family planning (also known as the rhythm method of birth control), which involves abstaining from sexual intercourse during the time that a woman can become pregnant in her menstrual cycle. The egg only survives in the fallopian tube from 24 hours after ovulation, so conception can only happen during a 24-hour period each month. However, this form of contraceptive is very unreliable and is not recommended for couples who are actively trying to avoid pregnancy. Which of the following is NOT a reason why this form of birth control is unreliable? A. Sperm can survive in the fallopian tubes for 3 to 5 days. B. Ovulation can be affected by stress or illness. C. Women always ovulate on the same day of their menstrual cycle every month. D. It is difficult to predict exactly when in her cycle a woman ovulates.arrow_forward
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