Oxygen is used up in the body of most organisms and Carbon dioxide is released. The body uses oxygen to break down glucose to supply energy tot he body. In result of this reaction carbon dioxide and water is released into the system along with energy. The carbon dioxide is then exhaled into the air by the respiratory system of the organisms.
Xerophytes are plants that have adapted to arid climates. They have evolutionary developed adaptations to reduce the rate of transpiration so as to conserve water.
Among the adaptations include; thick cuticle, small, thick leaves, reducing the surface area relative to the volume of the leaf, etc.
Additionally, they use CAM pathway as an alternative photosynthetic pathway to minimize water loss.