What is the difference between direct and indirect energy transfer in trophic levels? Please help!

Some substances but not other can cross the (blank) membrane of a cell

What is gene flow? apexa: selection for average traits b: when a population splits in twoc: a mutation becoming more commond: genes moving between two populations

Select the correct answer. which statement applies only to the axial skeleton, not the appendicular skeleton? a. it contains a pivot joint. b. it has muscles attached that work in pairs. c. it contains red bone marrow. d. it possesses fossa for bone articulation. e. it protects the heart and lungs.