What cell type secretes perforins as part of the nonspecific defense mechanism?
A) macrophages
B) helper T cells
C) plasma cells
D) mast cells
E) natural killer cells
Ans: E) natural killer cells
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What is diatomaceous earth? How is it used commercially?
What will be an ideal response?
Which of the following is not an event of phagocytosis?
A. Destruction B. Diapedesis C. Ingestion D. Phagolysosome formation E. Chemotaxis
Based on what you see here and your knowledge of selection, what inference can you make about the mouse population?
1.The population has undergone directional selection since the white mice blend into the environment.
2.Disruptive selection has led the population to two color variations, black and white.
3.There are two separate species of mice. The white species is dominant since it blends into the sand.
4.Owls and white mice are co-evolving to be able to feed at night.
An ovule
a. is the structure that develops into a seed. b. contains the microsporophyll. c. is produced on the surface of a male cone. d. is all of the above.