In certain cancerous cells, the cell divides continuously even in the absence of a growth factor (signaling molecule) that indicates the cell should divide. Which of the following could NOT explain this?
A) a receptor molecule that is always turned off
B) a receptor molecule that is always activated
C) a transduction pathway that is always turned on
D) a target protein that is always activated
E) a gene for cell division that is expressed when it should not be
Ans: A) a receptor molecule that is always turned off
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Four of the five answers are characteristics of diatoms. Select the exception
a. two-part silica shells b. photosynthetic c. some produce a toxin that accumulates in fish, crabs, and shellfish d. flagella e. live in lakes, seas, and damp soils
What would result if too many cells left the surface of the embryo to move inside during gastruation?
A. Too little endoderm, resulting in missing gut and organs B. Too little ectoderm, resulting in missing nervous system or skin C. Problems in muscle development D. Too little protoderm, resulting in missing organs Clarify Question What is the key concept addressed by the question? What type of thinking is required? Gather Content What do you already know about the fate of the surface cells? What other information is related to the question? Choose Answer Given what you now know, what information is most likely to produce the correct answer? Reflect on Process Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
A group of chemicals that at low doses reduces
fatigue and heightens awareness but at high doses elicits anxiety and irritability are a. depressants. b. stimulants. c. analgesics. d. hallucinogens. e. antipsychotics.
The pairing of homologous chromosomes during meiosis I is known as ________
Fill in the blank with correct word.