What has created at least half of the oxygen in Earth's atmosphere?
A) burning fossil fuels
B) trees in the boreal forest
C) phytoplankton in the ocean
D) plants, algae, and phytoplankton in the intertidal zone
C
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The lysosome contains ________ enzymes.
Fill in the blank(s) with the appropriate word(s).
Which observations illustrate shared ancestry by anatomical comparison studies? Check all that apply.A) The same structure has evolved to carry out different functions.B) Different structures evolve in similar ways when subjected to the same selective pressures.C) A structure becomes vestigial.D) Features are similar during embryonic development.
What will be an ideal response?
Clonal selection is an explanation for how _____
A) a single type of stem cell can produce both red blood cells and white blood cells B) V, J, and C gene segments are rearranged C) an antigen can provoke production of high levels of specific antibodies D) HIV (human immunodeficiency virus) can disrupt the immune system E) macrophages can recognize specific T cells and B cells
?
Figure 38.17
Use the figure above to answer the following question. At what partial pressure of oxygen do half the heme groups in human blood have bound oxygen?
A. 30 mm Hg B. 100 mm Hg C. 70 mm Hg D. 104 mm Hg E. 120 mm Hg