The first known fossils of living cells were preserved in rocks that are 3.5 billion years old, but scientists postulated that the first cells arose many millions of years prior to this time. These first cells were most likely ...
A. aerobic, photosynthetic, eukaryotic.
B. aerobic, photosynthetic, prokaryotic.
C. anaerobic, heterotrophic, prokaryotic.
D. anaerobic, heterotrophic, eukaryotic.
E. anaerobic, chemotrophic, eukaryotic.
C. anaerobic, heterotrophic, prokaryotic.
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Suppose two living plant cells are in contact with each other so that water, but not solutes, can pass
between them. The cells have the same water potential. One cell has ?P???0.3 MPa and ?S = ?0.5 MPa, while the other cell has ?S = ?0.3 MPa. What is the ?P of the second cell?
a. ?P = ?0.8 MPa b. ?P = 0 MPa c. ?P = 0.5 MPa d. ?P = 0.8 MPa e. ?P = 0.1 MPa
When two adjacent bases in the same strand of DNA dimerize (form a covalent bond between them), what happens to
the DNA?
a. the original strand of DNA now contains a new DNA sequence b. the original strand of DNA is kinked, which prevents DNA polymerase from working properly
c. the original strand of DNA is methylated, which causes the bases to mismatch d. the original strand of DNA is prevented from opening during replication, so this section of DNA will not be replicated e. the original strand of DNA is unaffected, so no additional mutations arise
Nematocysts are used for
a. reproduction. b. excretion. c. muscle action. d. circulation. e. defense.
DNA nucleotides include ________
A) uracil, guanine, adenine, and cytosine B) thymine, guanine, adenine, and cytosine C) thymine, uracil, adenine, and cytosine D) thymine, guanine, adenine, and uracil