During days 8 and 9 after fertilization in humans, ____.
A. amnion cleavage begins
B. a blastocyst forms
C. an embryonic disk is formed
D. implantation occurs
E. gastrulation occurs
Answer: D
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Which of the following statements about essential elements is FALSE?
a. An element with only one role in plant metabolism may still be essential. b. An essential element is necessary for normal growth and reproduction. c. Plant seeds in some cases contain enough of an essential element to sustain the adult plant. d. An essential element may occasionally be functionally replaced by another element. e. Some essential elements are required in only trace amounts.
Why are steroids considered lipids?
a. Because they are soluble in polar solvents. b. Because they are not soluble in polar solvents. c. Because they are soluble in polar solvents at certain temperatures. d. None of the above.
Kinetic energy stops increasing and the potential energy starts increasing
What will be an ideal response?
How does a cell typically know when to divide?
A) Cells have an internal clock and divide only when they reach a certain age. B) Tumor suppressor genes code for growth factor proteins that initiate cell division. C) Proto-oncogenes code for growth factor proteins that initiate cell division. D) Oncogenes code for growth factor proteins that initiate cell division.