Plants don't need a specialized respiratory system because they don't have lungs. They take in carbon dioxide and give out oxygen through their pores in their leaves and other tender parts.
Cyanobacteria were the first organisms to introduce oxygen into Earth's atmosphere. They were also known as blue-green algae, and is estimated that they first appeared around 3 billion years ago.
burns are estimated by class, 1st degree, 2nd degree, etc. there are characteristics associated with each degree. if you can see the muscle and fat tissue, that would be a 4th degree burn...
The guard cell is responsible for controlling the size of the stomata in leaves. These do so as a result of an interaction between potassium ions and water in and around the cells. When potassium ions accumulate inside the guard cells the water potential inside these cells is lower than that of the outside and as a result, water has to be taken in. This makes the guard cells turgid which in turn stretches them and results in the opening of the stomata. Meanwhile, when potassium ions accumulate outside the cell, the opposite scenario results. Water from inside the cell moves out, making the guard cells flaccid, thus causing these to cover (and effectively close) the stomata.
Answer:
the Soviet Union and U.S.A, Gemini VI, commanded by Mercury astronaut Wally Schirra and piloted by Tom Stafford, was supposed to have orbited on October 25, to rendezvous and dock with an Agena target vehicle. But the unpiloted Agena spacecraft blew up during launch that morning, stranding the crew waiting in their vehicle on Launch Complex 19.