Chapter 12 Lesson 1
- Transpiration- loss of water vapor through stomata of a leaf
- Photosynthesis- the process in which plants use light energy to produce food.
- Respiration- the process by which organisms break down food to release energy.
- Carbon dioxide needed for photosynthesis enters leaves through the stomata. Water vapor escapes during this process.
- Chlorophyll in plants captures sunlight. Photosynthesis splits the water molecules and makes glucose and oxygen, which are needed by all organisms.
- Through respiration, energy stored in glucose becomes available for cell activities.
Each stomata is surrounded by two guard cells that control the size of the opening. Water moves into the cell and out of the cell by osmosis. When guard cells absorb water, they swell and the stomata opens, letting carbon dioxide in. Water vapor escapes during the process. When guard cells absorb water, they swell and the stomata opens, letting carbon dioxide. Water vapor escapes during the process. When guard cells lose water, they relax and the stomata closes.
Chlorophyll is a pigment that traps light energy from plants to use in making food. Photosynthesis is the process in which plants use light energy to make their own food.
During photosynthesis, a plant makes food from light energy, carbon dioxide, and water in a series of chemical reactions. Some of the light energy trapped in the chlorophyll is used to split water molecules into hydrogen and oxygen. Light energy is then used to join hydrogen and carbon dioxide together to form a new sugar molecule. The sugar formed is used to form glucose, the food a plant uses for maintenance and growth. The process is illustrated in the following equation:
6CO2 + 6H2O + light energy = chlorophyll, sugar, and oxygen
Respiration is the process by which organisms break down food to release energy. Respiration that uses oxygen to break down food chemically is called aerobic respiration. Cellular respiration occurs in the mitochondria of all eukaryotic cells. Plant and animals need energy to build up and repair their cells, tissues, and organs. Sugar produced during photosynthesis by plant cells is used to make cellulose to build wall cells. Plants also use energy from the food they make during photosynthesis for growth and reproduction.
