Which statements are true of a white dwarf?
a. it has a red shell.
b. it is the result of the core collapse of a low-mass star that sheds its outer layers.
c. it emits massive amounts of light compared with other stars.
d. it strongly attracts all matter or energy that comes near it.
e. it cools down to become a black dwarf.

Ablastocyst is a group of cells that forms after a human egg is fertilized. the blastocyst consists of two types of cells. some of these cells will become the placenta. what do the other cells develop into?

Which codon is the code for the amino acid histidine (his)?

African penguins, which inhabit the coasts of southern africa, were classified as an endangered species in 2010. two significant threats to their survival are ecosystem damage from oil spills and overfishing by humans. overfishing depletes the food supply of african penguins. the best method to reduce the threat of overfishing would be to . the risk of oil spills could be reduced by increasing the use of , which should oil consumption. if an oil spill does occur, could be used to remove the oil so the ecosystem may more quickly recover.