Which of the following events occurred during the first trimester?
a. heart beat begins
b. lungs fully develop
c. bones become solid
d. fetus moves and kicks and swallows

Which technically is nasa developing that will astronauts reach mars

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?