Plant Processes: Photosynthesis, Respiration, and Plant Responses

1. Chapter 15 Plant Processes

2. 15.1 Photosynthesis & Respiration

3. Gas Exchange in Plants • Humans: • Plants:

4. Plants need water and CO2 to survive • ROOTS absorb most of the water & move it up through the plant • Stomata: small openings on leaves where water and gases enter & leave plants (**CO2) • Guard Cells: structures that swell & shrink to regulate the opening & closing of the stomata

5. Stomata

6. When guard cells lose water, they shrink and close the stomata. • Less CO2 enters and less H2O leaves • Stomata are usually closed at night or when the plant lacks water.

7. Open & Closed Stomata

8. Transpiration: • Loss of water vapor through the stomata of a leaf

9. Photosynthesis: • The process by which plants use CO2, water, and sunlight to produce food Chlorophyll • 6CO2 + 6H2O + light energy C6H12O6 + 6O2

10. Chlorophyll: • A pigment that traps light energy from the sun and gives leaves and stems in plants their green color

12. Steps of Photosynthesis • 1. CO2 & H2O are the “ingredients” • 2. These atoms are rearranged to form a new molecule (C6H12O6), a simple sugar called glucose • The energy in the chemical bonds of glucose is used by the plant for growth & reproduction

13. Photosynthesis Table

14. Products of Photosynthesis • O2 most is released through stomata • C6H12O6  main form of food for plant cells

15. Importance of Photosynthesis • 1. provides food for nearly all other organisms on Earth • 2. removes carbon dioxide from the atmosphere and replaces it with oxygen

16. Respiration: • Series of chemical reactions by which all organisms break down food to release energy • Occurs in the mitochondria of a cell

18. Respiration Equation • C6H12O6 + 6O2 6CO2 + 6H2O + energy • This equation is the exact reverse of photosynthesis!

19. 2 Types of Respiration • 1. Aerobic:occurs in the presence of O2 • 2. Anaerobic: occurs without O2 • Aerobic respiration combines oxygen and food to release the energy in the chemical bonds of food.

20. Cellular Respiration Table

21. Importance of Respiration • Energy in food is in a form that CANNOT be used by cells. • During respiration, food energy is converted into a form that all cells can use • Aerobic respiration returns CO2 to the atmosphere where it can be used again by photosynthetic organisms

22. 15.2 Plant Responses

23. Stimulus: anything in the environment that causes a change in the behavior of an organism • Response: change in behavior as a result of the stimulus

24. 2 Types of Stimuli • 1. Outside (phone ringing) • 2. Inside (chemical reactions & hormones) • ALL living organisms, including plants, respond to stimuli.

25. Hormones: • Substances made by cells for use somewhere else in the organism

26. Tropisms: • Response of a plant to an outside stimulus • Can be positive or negative (toward or away from the stimulus)

27. Thigmotropism: • plant response to touch • Gravitropism: • plant response to gravity • Phototropism: • plant response to light