Zircon crystals form from volcanic rock. The age of zircon crystals can be precisely measured. What exactly is measured in zircon crystals?
What will be an ideal response?
Zircon consists mainly of ordered arrays of zirconium silicate molecules (ZrSiO4). Some of the molecules in a newly formed zircon crystal have uranium atoms substituted for zirconium atoms. Uranium decays into lead. Therefore, the ratio of uranium atoms to lead atoms can be used to calculate the age of the crystal.
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If a woman has blood type O and a man has blood type AB, what is the probability that they will have a child with
blood type O?
a. 0 b. 1/16 c. 1/4 d. 1/2 e. 3/4
Inhibitors of enzymes can be either reversible or irreversible. In addition, most reversible inhibitors are either competitive or noncompetitive
Based on what you know about enzyme inhibition, classify the following examples as irreversible, competitive, or noncompetitive enzyme inhibition. A) competitive B) noncompetitive C) irreversible 1) Diisopropyl fluorophosphate binds to acetylcholinesterase and permanently inactivates the enzyme. Paralysis results. 2) A drug binds to the active site of an enzyme but disassociates and leaves the enzyme active. 3) A toxin binds to the surface of an enzyme. The enzyme then binds the substrate, but no product is produced. The toxin may disassociate and the enzyme will become active again. 4) Vitamin K is a coenzyme involved in blood clotting. An anticoagulant drug binds at the site of vitamin K bonding, blocking vitamin K binding and preventing clotting. Clotting resumes after the patient stops taking the drug. 5) Aspirin binds to prostaglandin synthetase and permanently stops its ability to produce prostaglandin.
Oogenesis differs from spermatogenesis in ________
A) the number of functional gametes produced B) when it is completed C) the size of gametes produced D) All of the above are true.
The background of a Brown and Hopps gram stained section is intense red. This could most likely be corrected in the future by changing the time in the:
a) iodine solution b) Gallego solution c) picric acid-acetone d) crystal violet