The definition of a churn is a device for making butter. An example of a churn is what the Amish use to make butter. verb. To churn is defined as to stir or shake milk or cream with intense movements in the process of making butter, to stir up and agitate, or to produce something at a rapid and regular rate. An example of to churn is for a boat to create waves while moving quickly through the water .
Quick Answer. Plants absorb energy from the sun and use photosynthesis to make sugars. Animals have mitochondria that use the sugars provided by plants to produce their own cellular energy. Plants that produce their own food, and food for other plants and animals using photosynthesis, are called autotrophs.
At night, when photosynthesis is not operating, plants take in atmospheric oxygen with which to oxidize carbohydrates, and the respiration can be measured. Almost all earthly life must produce energy by cellular respiration, the oxidation of carbohydrates (and other substances) to yield ATP. This in turn is used to provide energy to other cell activities. Plants are no different from animals in this respect. The difference is that plants produce their own carbohydrates, and oxygen, part of the time, which animals cannot.