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Gas Exchange
- *relates to how a cell gets raw materials (water, carbon dioxide) and releases waste products (oxygen, water)
- *carbon dioxide enters through the stomates
- -lower epidermis has more stomates than the upper
- -more carbon dioxide enters into the spongy layer
- -guard cells control the opening and closing by:
- A) Absorbing Water
- --stomates will open
- --guard cells swell
- B) Losing Water
- --stomates will close
- --guard cells relax
- -stomates remain open during the day
- why?--carbon dioxide allowed to enter so photosynthesis can occur
- -stomates close at night
- why?--will not lose as much water and energy
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Transpiration
*loss of water through the stomate
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Importance of Photosynthesis
- 1) Food production for plants
- 2) Plants remove carbon dioxide from the air and produce oxygen that most organisms need to stay alive
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Importance of Respiration
- 1) Help repair cells, organs, and tissue
- 2) Growth and reproduction
- 3) To make cellulose to build cell wall
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Photosynthesis Formula
6CO2 + 6H2O + sunlight energy >>>>> 6O2 + C6H12O6
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Respiration Formula
C6H12O6 + 6O2 >>>>> 6H2O + 6CO2 + energy
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Photosynthesis
*food making in plants
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Respiration
*burning of oxygen/food for energy
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Chemical Reactions in Plants
- 1) Light Dependent
- 2) Light Independent
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Light Dependent Reactions
- *reactions to photosynthesis that require light
- *chlorophyll traps light that will be stored in sugar
- *causes water molecules to split
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Light Independent Reactions
- *reactions to photosyntesis that do not require light
- *taking in carbon dioxide
- *makes stored food>glucose
- *ex: carrots, onions, potatoes
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Tropisms
*plant's reaction to a stimulus
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4 Types of Tropisms
- 1) Thigmotropism
- 2) Phototropism
- 3) Geotropism/Gravitropism
- 4) Hydrotropism
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Thigmotropism
*plant's response to touch
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Phototropism
*plant's response to light
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Geotropism/Gravitropism
*plant's response to gravity
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Hydrotropism
*plant's response to water
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Positive Tropisms
- *movement is towards the stimulus
- *ex: plants bend towards sunlight
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Negative Tropisms
- *movement is away from the stimulus
- *ex: roots growing downwards (away from sun)
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Plant Hormones
*hormone - chemical messengers
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5 Plant Hormones
- 1) Ethylene
- 2) Gibberlin
- 3) Cytokin
- 4) Abscidic Acid (ABA)
- 5) Auxin
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Ethylene
*stimulates ripening in fruit
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Gibberlin
*stimulates cell stem growth and seed germination
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Cytokin
*for cell division and ripening
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Abscidid Acid (ABA)
*keeps plants dormant in winter
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Auxin
*helps stem "stretch"/elongate on shady side as it responds to light
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Photoperiodism
- *the flowering response of a plant due to the change of light/darkness in a day
- *different plant species will flower in different seasons
- *the photoperiods will change with the seasons
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3 Photoperiods for Plants
- 1) Long Day Plants
- 2) Short Day Plants
- 3) Day Neutral Plants
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Long Day Plants
- *requires short nights
- *ex: spinach, lettuce, potatoes
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Short Day Plants
- *requires long nights
- *ex: poinsettas, strawberries, ragweed
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Day Neutral Plants
- *requires wide range of night lengths
- *ex: marigolds, corn
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Ways to Improve Crop Production
- 1) Biotechnology
- 2) Transgenic Crop
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Biotechnology
- *moving DNA directly from one plant to another
- *can be same or different plant species
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Transgenic Crop
*DNA from one species into another species
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2 Methods of Transgenic Cropping
- 1) Bacterial
- 2) DNA Particle Gun
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Bacterial Transgenic Cropping
*insert DNA using a virus or bacteria
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DNA Particle Gun
*shooting a DNA coated ball into the target cell of a plant
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