CHAPTER 11 – RESPIRATION AND PHOTOSYNTHESIS Photosynthesis
Plants absorb energy directly from the Sun to make their food. This biochemical process is called photosynthesis. The reactions of photosynthesis take place in chloroplasts, which are small organelles in the cytoplasm of plant cells.
? TEST TUBE 7. Where does the energy for all organisms on Earth come from? For photosynthesis, plants need:
• carbon dioxide, which they take in from the air through small openings in their leaves called stomata.
• water, which is taken in through their roots from the soil. This water is then transported to the leaves.
• sunlight, which supplies light energy.
• chlorophyll, a green pigment in the chloroplast that absorbs the light energy and uses it to power chemical reactions.
Sunlight
Oxygen Glucose Chlorophyll Water
)Fig. 11.4 Photosynthesis ? TEST TUBE 8. Explain the role of chlorophyll in photosynthesis.
Photosynthesis transforms the light energy from the Sun into glucose, which supplies chemical energy to the plant.
Oxygen is a waste product of photosynthesis. It is released from leaves through the stomata. The word equation for photosynthesis is:
carbon dioxide + water ?
sunlight
chlorophyll TEST TUBE
9. The oxygen released into the atmosphere by photosynthesis is very important to other organisms. Explain how organisms use oxygen.