What best describes index fossils?
a. Organisms that existed over a limited period
b. Organisms whose age is hard to detect
c. Fossils that are used in radioactive dating
d. Fossils of the most ancient organisms
Answer: a. Organisms that existed over a limited period
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Which one of the following is a monosaccharide and not a disaccharide?
A. lactose B. fructose C. sucrose D. maltose E. None of these sugars is a monosaccharide.
Which of the following anemias is associated with a vitamin B12 deficiency?
a. aplastic b. pernicious anemia c. hemolytic anemia d. leukemia e. iron-deficiency anemia
Organisms that thrive in extremely cold climates often produce proteins that act as "antifreeze". Given that all proteins bind to other molecules, how might such antifreeze proteins work?
A.) they bind to channels in the cell membrane, preventing water from seeping into or leaking out of cells B.) they bind to metal ions and each other, which attracts water molecules to form a thick gem that expands C.) they bind to proteins in the cell nucleus, promoting the expression of antifreeze genes D.) they bind by way of their beta sheets to tiny ice crystals, preventing their growth
In a completed Gram stain, gram-negative bacteria are colorless
Indicate whether the statement is true or false