yes it dose
no
nobody knows
Oxygen
Flowers do not give out oxygen, the green parts of a plant give out oxygen when the are engaged in photosynthesis.
They give off more oxygen during the day.
oxygen
That is a parasitic plant. An example is cuscuta
Sponges are considered ANIMAL life not plant life. Therefore they do not give off oxygen, they consume it.
A plant does give off Carbon Dioxide at night when there is not enough light for photosynthesis to occur.
I think when they receive carbon dioxide
Plant cells can give off oxygen when photosynthesis occurs. They give out carbon dioxide when they respire when there is no light available.
The way to improve oxygen in the air is by increasing life that give off oxygen as a byproduct such as plant life. Animals use oxygen and give off carbon-dioxide which is used by plants which in turn releases oxygen in the air.