Which of the following organisms first introduced oxygen into Earth's atmosphere?

A. cyanobacteria

B. methanogens

C. early protozoans

D. plants

E. green algae

Why does a block of metal sink in water but the same size block of wood float? The molecules in the metal are closer together than the molecules of the wood. The metal is more compact.

The process by witch gases trap heat near the earth is known as

What is the danger of combining foods?

Everyone at one time or another has had a hard time getting to sleep. What are some ways to overcome insomnia without drugs?

The carbon-dioxide content in the Earth's atmosphere before 1500 A. D. was between 200 and 300 ppm. The carbon dioxide content today is about 450 ppm. Which single historical development can be blamed for this increase? Select one: O a.

Which structure best makes Bermudagrass successful in preventing soil erosion

Part D Are there any similarities between this Galapagos research and Darwin's research? Explain your answer.

Although gender is not inherent in inanimate objects or in behaviors, we treat many objects and behaviors as if they were masculine or feminine. This cognitive organization of the world according to gender is referred to as?

Water changes temperature easily. true or false

redwoods are the tallest species of tree in the world. explain how transpiration causes water to travel from the roots to the branches of a tree this size.