What structure may have acted as a boundary for a cell-like environment before protocells formed?
a. acidic water from volcanic springs
b. chambers in rocks
c. metal ions from rocks
d. clay
e. lipid membrane
b
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Glucose is stored in plants as _________ and in animals as _________
A. glycogen; starch B. cellulose; glycogen C. starch; cellulose D. starch; glycogen E. cellulose; starch
Collecting ducts in the kidney lead
immediately into the a. renal cortex. b. renal medulla. c. renal pelvis. d. ureter. e. urethra
Which of the following crosses represents a dihybrid cross?
A. RD × Rd B. RrDd × RrDd C. RR × Dd D. RRrr × DdDd E. Rd × RR
Because of the high requirement for reducing power in nitrogen fixation, the nitrogenase enzyme that carries out the reaction is very sensitive to the presence of ________.
A. oxygen B. light C. carbon dioxide D. None of the choices are correct.