Name three plant-like organisms which cannot produce their own food.

Pretty much all plant organisms can produce their own food. However, organisms like mushrooms are often confused for plants, but they CANNOT make their own food.  

Mushrooms are fungus, meaning that they have to get their food from other dead or decaying organisms. This makes them different from both plants and animals because they don't eat food, but they don't make it for themselves either. They absorb it through their roots.

density and pressure

during expiration the diaphragm relaxes, which causes the diaphragm to move downwards. the contraction of diaphragm increases the space for expansion of lungs. hence, the diaphragm relaxes and positioned downward during expiration.