Antigens are
A) specific molecules, or parts of molecules, that the body recognizes as foreign.
B) proteins the body produces against invading substances.
C) cells that protect the body against invaders.
D) proteins on the surface of our cells to which pathogens attach.
E) enzymes secreted to destroy a pathogen's cell wall.
A
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You a given a plant tissue in the lab and asked to determine if the tissue is a source or a sink. Microscopic analysis reveals an abundance of colorless parenchyma cells with plastids. Only one biochemical test reacts positively with your sample. In the presence of iodine, the plastids turn a dark purplish color. Based on this information, you determine your sample is
A. a source because your sample contains plastids. B. a source because your sample is rich in carbohydrates. C. both a source and sink because it contains both plastids and carbohydrates. D. a sink because your sample is rich in carbohydrates.
Glacier ice occupied about __________% of Earth's land during the last Ice Age, then began retreating
about 17,000 years ago. Today, glacier ice occupies about __________% of the land surface. a. 30; 10. b. 50; 10 c. 73; 50 d. 80; 50 e. 15; 1
Which of the following is an exotic species?
a. Sumatran tiger b. koalas c. brown tree snake in Guam d. Atlantic cod
oogenesis in females produces _________
Fill in the blank(s) with the appropriate word(s).