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.
C
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How do cells use ATP?
a. ATP forms a barrier around the outside of the cell. b. ATP makes up the nuclear pore complex. c. ATP is the cell’s primary energy currency. d. ATP is used to transport waste to the plasma membrane.
Pores on the leaf surface that function in gas exchange are called
a) stomata. b) hairs. c) sclereids. d) xylem cells. e) phloem cells.
In species that are capable of both sexual and asexual reproduction, under which of the following conditions is sexual reproduction more likely to occur?
A. when males and females find each other B. when conditions for survival are favorable C. when conditions for survival are unfavorable D. cannot be determined: the conditions favor sexual over asexual remain a complete mystery.
From what molecule are the steroids derived?
a) Co2 b) cholesterol c) glucose d) glucagons e) phospholipids