What is the difference between early Earth's atmosphere and modern Earth's atmosphere?

What is the name of the idea that energy cannot be created nor destroyed

Conservationists to restore ecosystems. which activity will positively affect the abiotic conditions of an ecosystem?

Chimeras are interesting organisms that have two different sets of dna. chimeras occur when when two different zygotes fuse to form one organism. some chimeras have no outward symptoms,while some have two different eye colors it two different blood types what roles do mitosis and meiosis play in the process