Heterocysts
A. are found in nitrogen-fixing cyanobacteria.
B. are used to protect nitrogenase.
C. produce catalase.
D. generate oxygen.
E. are found in nitrogen-fixing cyanobacteria AND are used to protect nitrogenase.
E
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What is the basic problem with cloning adult animals?
a. obtaining enough DNA b. finding proper surrogates to carry the cloned embryos c. reprogramming the DNA d. obtaining DNA without mutations e. autoimmune rejection of the embryo by the surrogate
The smooth ER is the primary site for the synthesis of phospholipids and cholesterol needed to make ____
a. DNA b. ATP c. ribosomes d. hormones e. cell membranes
The half-life of Carbon-14 is approximately 5,700 years. Using this information scientists have been able to determine the age of some artifacts left by humans. A scientist wants to know approximately how old a piece of wood was that she found on the floor in an old cave that had recently been discovered. She removed the wood (with permission) to her laboratory. Her wood sample contained 2 grams
of Carbon-14 . If the age of the wood was determined to be 22,800 years old, how much Carbon-14 originally existed in this piece of wood? A. 32 grams B. 16 grams C. 12 grams D. 8 grams E. 4 grams
All types of internal fertilization require
A. specialized anatomical structures. B. transfer of a spermatophore to the female reproductive tract. C. a terrestrial environment. D. a penis in the male.