[Answer] 10. Which one of these contributes to the death of many sea turtles?

Step 1 : Introduction to the question "10. Which one of these contributes to the death of many sea turtles?"

...1. All of them 2. Six Pack Rings 3. Shrimp Nets 4. Plastic Bags Many turtles wash up dead due to our ignorance.

[Ans] What organism contributes 70 to 80 percent of Earth's oxygen?

Step 1 : Introduction to the question "What organism contributes 70 to 80 percent of Earth's oxygen?"

Tiny microscopic plants are at the base of the world's marine food chain. These phytoplankton are a form of algae and they produce between 70 and 80 percent of the oxygen in our atmosphere. Good ol' pond scum, the green slick riding the waves, and even some marine seaweed beds are colonies of algae. Trees and other green plants supply oxygen and are important to Earth's ecosystem, but without marine algae, oxygen-dependent life would not survive on planet Earth. Source: Ecology.com

[Answer] What organism contributes 70 to 80 percent of Earth's oxygen?

Step 1 : Introduction to the question "What organism contributes 70 to 80 percent of Earth's oxygen?"

...Tiny microscopic plants are at the base of the world's marine food chain. These phytoplankton are a form of algae and they produce between 70 and 80 percent of the oxygen in our atmosphere. Good ol' pond scum, the green slick riding the waves, and even some marine seaweed beds are colonies of algae. Trees and other green plants supply oxygen and are important to Earth's ecosystem, but without marine algae, oxygen-dependent life would not survive on planet Earth. Source: Ecology.com