1. I will review basic plant structure and investigate stomata.
Catalyst What adaptations allow plants to maintain their water on land?
I will review basic plant structure and investigate stomata.

2. The week…

3. EXPERIMENT RESULTS CONCLUSION Figure 39.5
In 1880, Charles Darwin and his son Francis designed an experiment to determine what part of the coleoptile senses light. In 1913, Peter Boysen-Jensen conducted an experiment to determine how the signal for phototropism is transmitted.
EXPERIMENT
In the Darwins’ experiment, a phototropic response occurred only when light could reach the tip of coleoptile. Therefore, they concluded that only the tip senses light. Boysen-Jensen observed that a phototropic response occurred if the tip was separated by a permeable barrier (gelatin) but not if separated by an impermeable solid barrier (a mineral called mica). These results suggested that the signal is a light-activated mobile chemical.
CONCLUSION
RESULTS
Control
Darwin and Darwin (1880)
Boysen-Jensen (1913)
Light
Shaded
side of
coleoptile
Illuminated
Tip
removed
Tip covered
by opaque
cap
covered
by trans- parent cap
Base covered
by opaque shield
Tip separated
by gelatin block
by mica
Figure 39.5

4. Went concluded that a coleoptile curved toward light because its dark side had a higher concentration of the growth-promoting chemical, which he named auxin.
The coleoptile grew straight if the chemical was distributed evenly. If the chemical was distributed unevenly, the coleoptile curved away from the side with the block, as if growing toward light, even though it was grown in the dark.
Excised tip placed
on agar block
Growth-promoting chemical diffuses into agar block
Agar block with chemical stimulates growth
Control (agar block lacking chemical) has no effect
Control
Offset blocks cause curvature
RESULTS
CONCLUSION
In 1926, Frits Went’s experiment identified how a growth-promoting chemical causes a coleoptile to grow toward light. He placed coleoptiles in the dark and removed their tips, putting some tips on agar blocks that he predicted would absorb the chemical. On a control coleoptile, he placed a block that lacked the chemical. On others, he placed blocks containing the chemical, either centered on top of the coleoptile to distribute the chemical evenly or offset to increase the concentration on one side.
EXPERIMENT
Extracted the chemical messenger for phototropism, auxin, by modifying earlier experiments

5. Hormones chemical signals that allow an organism to respond/grow and develop

6. Hormone Redux.
Auxin – stimulates growth, formation and branching of roots.
Cytokinins – lateral cell division
Gibberellins – stem elongation, fruit growth, seed germination
Abscisic Acid (ABA) – slows down growth for dormancy, closes stomata when plant is stressed
Ethylene – fruit ripening, ageing and death.
** Remember, you are an expert on one of these. ***

8. Land. Struggles. Surviving.
Less water, so plants needed to avoid drying out
No support against gravity
Surviving.
Cuticles
Vascular tissue
Roots
Leaves

9. Seeds!
MULTI-CELLULAR
RESISTANT
DORMANCY
DISTANCE
FAVORABLE CONDITIONS

10. Angiosperms WHY?!? aka flowering plants flowers and fruits
Are the most widespread and diverse of all plants
WHY?!?

11. The Root System
Underground (usually)
Anchor the plant in the soil
Absorb water and nutrients
Conduct water and nutrients
Food Storage

12. The Shoot System Above ground (usually)
Elevates the plant above the soil
Many functions including:
photosynthesis
reproduction & dispersal
food and water conduction
** the shoot system includes the leaves and the reproductive organs

13. Tissues.

14. Transport Phloem Transports food (sugars) and other items Xylem
Transports water and minerals

15. Make & Support Parenchyma Plant metabolism Most with chloroplasts
Sclerenchyma
Dead cells with super thick cell walls that provide support
Collenchyma
- Living support cells.

17. 11.29.16 Catalyst – What is the function of the stomata?
I will compare stomata frequencies.

18. Stomata

19. Today Stomata Lab While you wait for the polish to dry…
Prepare and analyze 3 samples
Today’s goal – one leaf completed.
Completed Lab due Friday
While you wait for the polish to dry…
Color code the leaf diagram

20. Hormones help plants maintain homeostasis
Homeostasis – an organism’s ability to maintain a stable internal environment while the external environment changes

21. Tropism – when an organism responds to the environment’s stimuli
Phototropism - light
Thigmotropism – touch/contact
Gravitropism – gravity