Strategies for writing an effective introduction. Start by thinking about the question (or questions) you are trying to answer. Your entire essay will be a response to this question, and your introduction is the first step toward that end.
A: Plants release oxygen as a by-product of photosynthesis, a process in which carbon dioxide is converted into sugar. The sugar is then used as an energy source for the plant. When oxygen is produced through photosynthesis, it is released by the plant into the atmosphere. The sugars produced by photosynthesis are utilized by combining them with oxygen through a process called oxidation. Photosynthesis chemically converts sunlight into energy after being collected by special cells in their leaves known as chloroplasts.
1 Students know plants use carbon dioxide (CO 2) and energy from sunlight to build molecules of sugar and release oxygen. 2  2g. 3  Students know plant and animal cells break down sugar to obtain energy, a process resulting in carbon dioxide (CO 2) and water (respiration).