The principle greenhouse gas is understood to be
group of answer choices
carbon
co2
nitrous oxides
sulfur oxides
cfcs

sex cells are usually half's then they find another half and make a fertilize egg

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.

essentially, one bacterial cell splits into two daugurer cells. bacterial offspring don't need or get care from their parents because they are in a sense their own parents. that said, some bacteria can and do depend on other bacteria especially in harsh environments such as bacterial microfilms in hot water tanks.