Announcements

1
Announcements

• Guest Lecturer, Thursday, Jan. 29
• Horticulturist, Toledo Zoo
• Vegetative Propagation
• Exam 1 Tuesday, Feb. 3
• Chapters 1-4
• Multiple choice style

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Modified leaves

• Carnivorous plants
• http//www.carnivorous-plants.co.uk/dionaea/video.
  asp
• http//www.carnivorous-plants.co.uk/dionaea/video.
  asp

3
Ch. 4 Plant Physiology
4
Net flow in whole plants
5
Movement of water

• Plants obtain water minerals from soil
• Water moves up into the entire plant through the
  xylem
• Movement of water depends on transpiration pull
  cohesion of water molecules
• Passive process

6
The availability of soil water and minerals
Long-distance transport of water from roots to
leaves
7
Compartments of plant cells and tissues and
routes for lateral transport

• Symplasm
• Cytoplasm
• Apoplast
• Cell wall

8

• soil
• epidermis
• root cortex
• Casparian strip
• xylem tissue
• leaves

Lateral transport of minerals and water in roots
9
Ascent of xylem sap

• transpirational pull
• flow from greater to lower water concentration
• relies on cohesion adhesion of water
• cavitation breaks chain of water molecules

10
Movement of sugars

• sugars move from the source
• Photosynthetic leaves
• Storage organ
• to the sink
• Growing organs
• Developing storage tissue
• through mass flow in phloem
• Pressure Flow hypothesis

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Phloem transport

• pressure flow
• high sugar concentration at source
• sugar diluted with water from xylem creating
  pressure for flow
• sugar unloaded at sink where it is metabolized
  or converted to starch
• excess water flows to xylem back to source
• translocation movement of food from source to
  sink(s)

Pressure flow in a sieve tube
12
Sugar and Slavery

• Very few plants can store sugar as sucrose
• Exceptions
• Sugarcane
• Sugar bee

13

• Pick up VARK test as you come in
• Question page Answer page

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VARK Testhttp//vark-learn.com/

• Questionnaire
• http//vark-learn.com/documents/general.pdf
• Scoring
• http//vark-learn.com/documents/scoring.pdf
• Learning tips
• http//vark-learn.com/english/page.asp?phelpsheet
  s

15
Life processes are driven by energy

• Plants are dynamic metabolic systems
• 100s of reactions occur every second
• Processes can be
• energy consuming (endergonic) or
• energy releasing (exergonic)
• Based on chemical bonds

16
Cellular respiration

• Chemical-bond energy in sugars is converted to
  energy-rich compound ATP which can then be used
  for other metabolic reactions

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Energy yield depends on oxygen

• Aerobic (with oxygen)
• 36 ATP molecules per glucose molecule
• Anaerobic (without oxygen)
• 2 ATP molecules per glucose molecule

18
Life on Earth depends on flow of energy from sun
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photosynthesis

• Photo means light and synthesis means to make
• Process in which plants convert carbon dioxide
  and water into sugars using solar energy
• Occurs in chloroplast

20
Site of photosynthesis
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• Chlorophyll
• Absorbs red blue light
• Reflects green light

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Rubisco

• Ribulose bisphosphate carboxylase
• Enzyme in Calvin Cycle
• Most abundant protein on Earth
• 12.5-25 total leaf protein

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Photosynthesis
6 CO2 6 H2O C6 H12 O6
6 O2
carbon dioxide water glucose sugar
oxygen

• photosynthetic products stored as starch
• Starch glucose polymer

STARCH
Tracking atoms
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The Big Dilemma

• Guard cells of chloroplasts regulate
• Rate of water loss by transpiration
• Rate of photosynthesis by controlling CO2 uptake
• When water loss uptake, guard cells lose turgor
  close stomata, limiting photosynthesis

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Types of photosynthesis

• C3
• Stomata open during day
• C4
• CO2 temporarily stored as 4-C organic acids
  resulting in more more efficient C exchange rate
• Advantage in high light, high temperature, low
  CO2
• CAM
• Stomata open during night
• Advantage in arid climates
• http//eee.uci.edu/99w/07350/Doc/C3C4CAM.html
• http//eee.uci.edu/99w/07350/Doc/C3C4CAM.html

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