The structural support of xylem is mainly due to the presence of a compression and decay-resistant tough polymer known as
a. sporopollenin
b. chitin
c. cellulose
d. lignin
e. restin
Answer: d. lignin
Biology & Microbiology
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An epidermal growth factor (EGF) stimulates a cell to enter mitosis by binding to a receptor on the cell's plasma membrane. The EGF receptor is a product of a _____ gene
a. repressor b. structural c. master d. proto-onco e. growth
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Which biome is a treeless plain that occurs
around the Arctic Circle? a. shortgrass prairie b. taiga c. cold desert d. cold grassland e. tundra
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Who proposed the geological theory of catastrophism?
A) Darwin and Wallace B) Cuvier C) Lamarck D) Darwin E) Plato
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