If a disease attacked this type of white blood cell, a person would no longer be able to mobilize his or her specific defenses
A) plasma cells
B) helper T cells
C) cytotoxic T lymphocytes
D) B lymphocytes
B
You might also like to view...
RNA cannot be cloned directly. ________, a viral
enzyme, is used to convert single-stranded RNA into ___________for cloning. Fill in the blank(s) with the appropriate word(s).
An otolith is one of the functional parts of the
a. eye. b. Pacinian corpuscle. c. vestibular apparatus. d. taste bud. e. pits, or heat-sensing devices, of snakes.
Which gland is the remnant of the "third eye"?
a. pineal b. pituitary c. thyroid d. parathyroid e. thymus
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to radioactively label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
a) Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive b) Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long c) Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins d) There is no radioactive isotope of nitrogen