The Earth's primordial atmosphere had little if any of which of the following gasses?
a) Sulfur
b) Carbon Dioxide
c) Nitrogen
d) Oxygen
e) Water
Answer: d) Oxygen
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Which statement about guard cells is false?
A. Fern guard cells shrink and swell in concert with adjacent epidermal cells. B. Angiosperm cells shrink and swell in concert with adjacent epidermal cells. C. Angiosperm guard cells exchange solutes with adjacent epidermal cells. D. The resting state of guard cells is closed.
Sponges feed on attached algae
Indicate whether the statement is true or false
What structure holds the sister chromatids to the spindle fibers?
a. kinetochore b. centromere c. chromatin d. cyclin e. MPF
Which of the following best represents a measure of ecological density?
A) number of frogs per meter of pond shoreline B) number of birds per hectare C) number of mammals per meter D) number of fish per volume of ocean