"The PitX1 gene in some populations of stickleback fish is expressed during development in three different cell types, leading to development of the jaw, the pituitary and pelvic spines. What causes expression of this gene in three different cell types?"

The seed coat's most important function is to provide a) a nonstressful environment for the megasporangium. b) the means for dispersal. c) dormancy. d) a nutrient supply for the embryo. e) desiccation resistance.

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

In this assignment, you will analyze an example of speciation by researching the finches of the galapagos islands. then you will answer questions to construct explanations and draw conclusions based on the information you gather. someone plz !