What are 2 ways the structure of pine leaves adapts these trees for life in dry environments?

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

In which way are mercury and venus similar? they both rotate from east to west. they are both small and rocky. they both have thick atmospheres. they both are similar to earth in structure.