Consider an X-ray binary system in which a compact object, surrounded by an accretion disk, is in a binary orbit with another star. All of the following statements about such accretion disks are true except:
A) The radiation from an accretion disk may vary rapidly in time.
B) The compact object may be either a neutron star or a black hole.
C) X-rays are emitted by the hot gas in the accretion disk.
D) Several examples of flattened accretion disks being fed by a large companion star can be seen clearly in photos from the Hubble Space Telescope.
E) The accretion disk consists of material that spills off the companion star.
Question 2
The nucleus of a comet is typically
A) a few hundred kilometers across, and bright, shiny white from its ices.
B) a few meters in diameter.
C) located between the orbits of Mars and Jupiter.
D) a few kilometers in size, and very low in density.
E) very durable, made of iron.
The mammalian urinary system including the basic functional unit of the nephron.
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Gene editing using the CRISPR-Cas9 system.