The minimum number of mutations that is required before cancer is likely to develop is
_____.
a. one
b. two
c. three
d. four
C
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The developing embryo implants into the uterine lining at about five days after fertilization. At this stage, it is a fluid-filled ball of cells called a ____
Fill in the blank with the appropriate word.
Which statement is NOT generally characteristic of parasites?
a. They are specialists and usually are able to affect only one variety of hosts. b. They inflict serious injury and kill their hosts. c. Some reside inside their hosts, whereas others live outside their hosts. d. Their host may be a plant as well as an animal. e. Plants as well as animals can be parasites.
Newly synthesized membrane lipids are found in both halves of membrane bilayers because they are
a. synthesized on both surfaces. b. removed and transported to these locations by lipid transport proteins. c. synthesized on one surface and flip spontaneously to the other surface. d. synthesized on one surface and flipped to the other surface by proteins called flippases.
In extremely cold regions, woody species may survive freezing temperatures by _____
A) emptying water from the vacuoles to prevent freezing B) decreasing the numbers of phospholipids in cell membranes C) decreasing the fluidity of all cellular membranes D) increasing cytoplasmic levels of specific solute concentrations, such as sugars