Assume that a woman has a "normal" 28-day reproductive cycle. She is concerned about the times in which she may get pregnant. Her partner tells her that the only day she has to worry about in terms of getting pregnant is the day she ovulates. Explain to
her why this is not the case.
What will be an ideal response?
Typically, an egg survives about 1 day, and sperm survive about 2 or 3 days (but possibly up to 5 days). This means any sperm deposited in the female system a few days prior to ovulation could fertilize the egg. Because the egg lives only about 1 day, the female should be concerned about the day following ovulation. This typically gives a 4-day window of concern. Further, the timing of ovulation is uncertain, so this must be accounted for as well.
You might also like to view...
When comparing root systems of corn plants growing on a square foot in a cornfield with the root systems of natural prairie plants growing in a meadow, what result do you expect to see?
A) The overall mass of roots will be identical in a cornfield and on a meadow. B) The mass and length of roots in a cornfield will be higher because soil is fertilized. C) The mass and length of roots on a meadow will be higher because soil is poorer and there is higher diversity of plants. D) The overall mass of roots on a meadow will be lower, but the length will be higher since roots need to grow deeper to reach nutrients.
Effector cells
a. are fully differentiated lymphocytes. b. manufacture and secrete antibodies. c. can develop from either T or B cells. d. secrete antibodies or interleukins depending on their origin. e. include all of these descriptions.
A researcher is working to generate a new cancer drug. Thus far, he has identified a compound that can reduce the size of tumors in the lung. However, in order for the drug to work, the lung tumor has to be small. In addition, the tumor cannot have metastasized (spread to other areas of the body). Furthermore, he knows that the drug acts to prohibit the signaling from one tumor cell to another tumor cell. Given the above information, this new drug prohibits:
A. paracrine signaling between tumor cells. B. autocrine signaling between tumor cells. C. synaptic signaling between tumor cells. D. endocrine signaling between tumor cells.
What changes does an animal that moves from water to land have to accommodate
a. Change in oxygen content b. Regulation of body temperature in a more extreme environment c. Wider diversity of habitats d. About 1000 times less buoyant density and 50 times less viscosity than water e. All of the choices are challenging of life out of water