Scientific evidences suggest that oxygen gas

appeared on earth about ____ years ago.



a. 38,000,000,000
b. 25,000,000,000
c. 2,300,000,000
d. 380,000,000
e. 4,500,000


C

Biology & Microbiology

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To become bound to hemoglobin for transport in a mammal, atmospheric molecules of oxygen must cross _____

A) zero membranesâ€"oxygen binds directly to hemoglobin, a protein dissolved in the plasma of the blood B) one membraneâ€"that of the lining in the lungsâ€"and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood C) two membranesâ€"in and out of the cell lining the lungâ€"and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood D) four membranesâ€"in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillaryâ€"and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood E) five membranesâ€"in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary, and into the red blood cellâ€"to bind with hemoglobin

Biology & Microbiology

If you are tossing a six-sided die, what is the probability of getting either a 1 or a 2 on your first toss AND a 1 or a 2 on your second toss?  

A.  1/18 B.  1/9 C.  1/6 D.  1/3 E.  2/3 Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? · What key words does the question contain? Gather Content · What do you already know about probability? Consider Possibilities · What other information is related to the question? Which information is most useful? Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Biology & Microbiology

The chief function of root hairs is to

A) decrease the anchoring power of roots. B) increase the surface area for efficient absorption of water and minerals. C) provide a direct passageway from the soil to the vascular cylinder.

Biology & Microbiology

In the chemical sodium chloride, the positively charged sodium and negatively charged chlorine atoms are held together by a(n) _____ bond.

A. ionic
B. covalent
C. hydrogen

Biology & Microbiology