Which statement is true of cephalochordates?
a. They lack pharyngeal slits.
b. They have existed for 500 million years.
c. They have well-developed brains.
d. They are excellent hunters.
b. They have existed for 500 million years.
You might also like to view...
What enzyme is responsible for replicating the ends of chromosomes in a eukaryotic cell?
a. DNA polymerase b. RNA polymerase c. primase d. telomerase
If thyroid hormone levels are very high in the blood, what hormone level would be low in the blood?
a. parathyroid hormone (PTH) b. calcitonin c. thyroid-stimulating hormone (TSH) d. inhibin e. cortisol
The chemical group box 1 in the accompanying figure is a:
a. pyrimidine. b. purine. c. phosphate. d. amino acid. e. covalent bond
Which of the following statements about protein kinase A (PKA) is false?
a. In the inactive state, PKA exists as a tetramer of two regulatory (R) and two catalytic (C) subunits. b. PKA binds a total of four molecules of cAMP, one on each of the four subunits. c. PKA binds a total of four molecules, two molecules on each of the two regulatory (R) subunits. d. Once activated, the catalytic (C) subunits dissociate and activate target molecules.