In a transmission electron microscope, the "lenses" are
A. made of glass.
B. thin films of metal.
C. lasers.
D. magnets.
E. vacuums.
Answer: D
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One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg.
A. chiasma B. homologue C. kinetochore D. synapsis E. synaptonemal
Cardiac muscle differs from skeletal muscle in that
A) all cardiac muscle is under involuntary control. B) cardiac muscle is capable of relaxation. C) cardiac muscle contracts in response to an electrical or chemical signal. D) cardiac muscle is excitable and can shorten. E) cardiac muscle gets longer rather than shorter when excited.
The semilunar valves:a
prevent blood from moving from the atria back into the veins. b. prevent blood from moving from the ventricles back into the atria. c. prevent blood from moving from the arteries back into the ventricles. d. prevent blood from moving backwards in the capillaries. e. prevent blood from moving backward in the arteries.
Which of the following is useful in distinguishing between bacterial, archaeal and eukaryotic cells?
A. The presence of membrane-delimited organelles within the cytoplasm B. The use of DNA for the storage of genetic information C. The presence of ribosomes for the synthesis of proteins D. All of the choices are correct.