What happens during crossing over and what is the significant?

Turtle hatchling survivorship rate is low in many turtle species due to predation. amanda researched the predatory rate on a species of turtle eggs in the red river. the eggs were harvested from trapped turtles and the egg's cloaca film (reproductive discharge) was either washed off or left on once gathered. research suggests that predators use the female's cloaca scent to locate the eggs. the eggs were only handled when wearing gloves and then reburied along islands where the turtles were trapped. the nests were monitored by cameras and manually on foot and data on nest predation were recorded. a. based on the experimental design, what is the dependent variable? b. based on the experimental design, what is the independent variable? c. based on the experimental design, what is the control?

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

What are the student's observations and inferences before he starts his investigation?