Which of the following is true?
a. introns have complementary sequences in dna
b. a pre-mrna molecule is longer than the gene from which the molecule was transcribed
c. a promoter is an intron
d. mrna molecules made from the same gene are always edited the same way

The study of interaction between living organisms and their enviroment is called (a) phytogeography (b) ecology (c) phytosociology (d) ecosystem

Ture or false evidence for evolution includes millions of fossils

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star. reset submit