Which of the following poses the best evidence that cell-signaling pathways evolved early in the history of life?
A) Cell-signaling pathways are seen in "primitive" cells such as bacteria and yeast.
B) Bacteria and yeast cells signal each other in a process called quorum sensing.
C) Signal transduction molecules identified in distantly related organisms are similar.
D) Most signals in all types of cells are received by cell surface receptors.
C
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Cartilage injuries do not repair themselves because ________. a. All of these choices are reasons cartilage injuries do not repair themselves
b. cartilage does not receive nutrients very easily c. cartilage does not contain blood vessels d. None of these are reasons as cartilage does heal itself. e. cartilage does not divide in adults
The primary root of a seedling grows down
a. to avoid light. b. in response to gravity. c. because the cells on the upper surface of the root elongate more rapidly than those on the lower surface of the root. d. in response to different concentrations of auxin. e. because of all of these except "to avoid light."
Describe the traits that make Pisum sativum an ideal organism for genetic studies. Why did Mendel ultimately decide not to include exterior seed coat color (gray vs. white) as one of the traits he analyzed?
What will be an ideal response?
Proper cross-matching of blood type is essential for safe blood transfusion
What is the general rule for safe blood transfusion, and what are the consequences if a patient receives the incorrect blood type by accident? If a patient's blood type is unknown, what is the safest course of action?