Mutualism, Commensalism, parasite-host, predictor-prey

Which of the following systems in absorbing oxygen and releases carbon dioxide

Nasa scientists must work together to make sure that everything is correct and accounted for when launching a shuttle. besides a physicist, what other type of scientist would be in making sure that the shuttle has the appropriate type and amount of fuel to reach its destination?

If you have a difficult time knowing where your hand is without looking at it you may be having a problem with your what ?