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Thinking Scientifically
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1. Is the presence of a complete set of genetic instructions in a fertilized ovum consistent with the hypothesis of preformation or epigenesis?

2. When an isolated sperm is mechanically injected into an oocyte outside the woman’s body, and the treated egg is then placed in the woman’s body, no embryo develops. Why doesn’t development ensue?

3. What technology would be necessary to enable a fetus born in the fourth month to survive in a laboratory setting?

4. What kinds of studies and information would be necessary to determine whether exposure to a potential teratogen during a war can cause birth defects a year later? How would such an analysis differ if it was a man or a woman who was exposed?

5. What factors contribute to longevity?

6. In the year 2050, 1 in every 20 persons in the United States will be over the age of 85. What provisions would you like to see made for older people of the future (especially if you will be one of them)? What can you do now to increase the probability that your final years will be healthy and enjoyable?


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Additional Questions and Terms

1. How would you produce:

  • a. A double newt embryo?
  • b. A frog that forms from a somatic cell?
  • c. A fruit fly embryo with two rear ends?
  • 2. Cite two example of work done in model organisms that also applies to medical condition in humans.

    3. Men who have the genetic disorder cystic fibrosis often lack vasa deferentia. Why are they unable to father children?

    4. Infertility patients in the past have been advised to abstain from intercourse until an ovulation test shows that the woman has ovulated. What evidence indicates that is advice is incorrect?

    5. A woman has been pregnant for 41 weeks. Her doctor performs a Caesarian section to deliver the child because biochemical tests indicate that the cells of the placenta are dying. Why it is vital to the child’s survival to perform the Caesarian section?

    6. Methotrexate is a drug traditionally used to treat cancer, but it can also stop growth of an ectopic pregnancy (an embryo developing in a fallopian tube) and can cause abortion. How can one drug have such different applications?

    7. Contraception literally means "against conception." According to this definition, is an intrauterine device a contraceptive? Why or why not?

    8. Why might lists of leading causes of death differ in different parts of the world, or even in different communities within a nation?

    9. What problems would a scientist likely encounter in studying the inheritance of longevity?

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