2. What is gas exchange in plants? When we inhale, we breathe in a mixture of gases we need for survival When we exhale, we breathe out the waste products In plants, CO₂ and H₂O are two substances needed for survival CO₂ enters through the stomata H₂O is absorbed through roots of the plant and released as water vapor through the stomata
3. Gas Exchange Light, H₂O and CO₂ all affect the opening and closing of stomata Stomata are usually open during the day and close at night When stomata closes, less CO₂ can enter and less H₂O can escape When plants lose water vapor through stomata, this is called transpiration
4. Photosynthesis Photosynthesis is the process in which plants use light energy to make food Chlorophyll is a chemical in plants that helps to capture this light energy Other than light, plants also need H₂O and CO₂ These molecules combine to form an organic compound, a carbohydrate (sugar) called glucose
5. Process of Photosynthesis 6CO₂ + 6H₂O + light energy C₆H₁₂O₆ + 6O₂ Carbon dioxide + water + light (and chlorophyll) produces glucose and oxygen A plant needs 6 molecules of carbon dioxide (CO₂) and 6 molecules of water (H₂O) to make one molecule of glucose (C₆H₁₂O₆) The chemical bonds in glucose contain the energy the plant needs for growth and survival and is the main source of food for plants Oxygen is also produced during photosynthesis and released through plant stomata
