About how long ago did the first single-celled life form appear on Earth? A. 130 million years ago
B. 1.5 billion years ago
C. 2.5 billion years ago
D. 4.1 billion years ago

Tlymphocytes mature in the? a. thyroid gland. b. bone marrow. c. spleen. d. thymus.

When ash and dust begin to settle on the ground, they eventually become compacted by

Suppose a particular species of tulip plant has three alleles for the gene that codes for flower color. the cr allele produces red tulips, the cp allele produces purple tulips, and the cw allele produces white tulips. cr is dominant over cp and cw, and cp is dominant over cw. for each of the following crosses, determine the expected ratio of offspring for each flower color. cr cp x cp cw cr cw x cp cw 1 red: 1 purple : 0 white, 1 red: 2 purple: 1 white, 2 red: 1 purple 1 white, 1 red: 3 purple : 0 white, 2 red: 0 purple : 2 white, 2 red: 2 purple : 0 white