Does respiration always involve the release of CO2 as a waste?
I got lost in a 5th grade science lesson regarding photosynthesis. I started spinning about concerning the fact that photosynthesis releases O2 as a waste, but “respiration” in a plant releases CO2 as a waste. It seemed to me that “respiration” would apply to any gas that is taken in and converted to another gas that is expelled as a waste, but perhaps not. I did a lot of researching on the question this morning including checking out Khun Acadamy, among other sites.
Here is the lesson that started it all:
Green plants use energy through a process called photosynthesis. This process converts solar energy into chemical energy the plant can use for growth and maintenance. It needs chlorophyll to occur and takes place in the leaves of green plants. The three ingredients are carbon dioxide, water, and light. The products of photosynthesis are food and oxygen.
What happens during photosynthesis? A plant takes carbon dioxide in through cells in its leaves. Water comes in through the roots and moves up to the leaves. Light from the sun is absorbed by chlorophyll in the plant’s cells. When carbon dioxide, water, and light are brought together, the plant manufactures sugar and starches, or food. These starch and sugar foods store the energy from the sun in the cells. The food produced by this process that is not used up is stored in a structure inside the cell called a vacuole. Oxygen is released into the air as a waste product of photosynthesis.
Photosynthesis combines carbon dioxide, water, and light to produce food for the plant. But how does the plant get energy from this food? Respiration is the process plants use to change food into energy. This respiration does not mean that plants breathe like animals with lungs. They use oxygen to burn up starches and sugars to release energy. The food chemicals combine with oxygen, and energy is then made available for each cell to grow and reproduce.