1. Chapter 15
Plant Processes

2. 15.1 Photosynthesis & Respiration

3. Gas Exchange in Plants Humans: Plants: INHALE EXHALE N O2 CO2
H2O vapor
H2O

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 Ingredients Products 6 CO2 (carbon dioxide)
C6H12O6 (glucose)
6 H2O (water)
6 O2 (oxygen)
Light energy

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
Ingredients
Products
C6H12O6 (glucose)
6 CO2 (carbon dioxide)
6 O2 (oxygen)
6 H2O (water)
Energy

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: Gravitropism: Phototropism: plant response to touch
plant response to gravity
Phototropism:
plant response to light