1. You have a reading quiz at the start of class.
Good Afternoon!
Please hand-in your xylem vs. phloem comparison chart in the green bin.
Put up your dividers.
You have a reading quiz at the start of class.

2. What are we doing today? Reading Quiz (Ch. 26.1-2) Video: “Growing”
Lecture: Plant Growth & Development
Environment & Genetics
Gibberellins & Auxin
Return Ch. 21 & 24 Tests
Log book check-in/ Final paper draft

3. “Growing”

4. 26.1 – What are key factors in plant growth & development?

5. 26.1 – What are key factors in plant growth & development?
Environmental cues
Receptors
Hormones
Genome

6. 26.1 – What is the evolutionary benefit of seed dormancy?

7. 26.1 – What is the evolutionary benefit of seed dormancy?
Some dormant seeds are unable to germinate even when the conditions for germination are favorable. Why?

8. 26.1 – What is the evolutionary benefit of seed dormancy?

9. 26.1 – How can seed dormancy be broken? (How do seeds germinate?)
SEEDS very negative water potential – will take in water if seed coat is permeable

11. 26.1 – What is the relationship between hormones and receptors?
HORMONES – chemical signals that act at very low concentrations at sites distant from the source
PHOTORECEPTORS – pigments associated with proteins that respond to light (environmental cue) and regulate developmental processes which are responsive to light (e.g. seed germination)

12. 26.1 – What is the relationship between hormones, receptors and plant development?
Environmental cues/ hormones  receptors  relay molecules  (encoded by genes) regulatory proteins & enzymes  response

13. 26.2 – Gibberellins
Seed germination (e.g. trigger synthesis of digestive enzymes to digest endosperm to release nutrient monomers to use in cell production)
Stem growth (effect on dwarf plants) – control flower height (artificial selection)
Fruit development – seeds are source of fruit growth (grape experiment – way to make big seedless grapes)

14. 26.2 – Auxin
Phototropism – response to light (higher concentration on shaded side)
Diffuses in polar fashion - unidirectional (stimulating cell elongation)
Gravitropism – response to gravity
Root initiation (experiment to induce roots in shoots with auxin solution)
Leaf abscission (autumn leaf fall – decrease in auxin through petiole)
Apical dominance (apical buds inhibit growth of auxiliary buds – allows for growth of main stem - Christmas trees)
Fruit development (parthenocarpy fruit formation without fertilization – seedless grapes, bananas and cucumbers)
Cell elongation – auxin induced cell expansion (acid growth hypotheses)

15. 26.2 – Plant Hormones vs. Animal Hormones
ACTIONS of plant hormones are NOT unique and specific – unlike animal hormones
PRODUCTION of plant hormones occur at tissues triggered by different cues (unlike in animals where usually a specific organ or site produce hormones)

16. Gibberellin & Auxin Venn Diagram

17. Reminders!
DRAFTS of final paper submitted BEFORE Saturday will get feedback this weekend.
PROJECT due TUESDAY (final paper, log book, photos) – TIPS on how to write a scientific paper are posted on homework blog.
CH 25 & 26 TEST on THURSDAY
Ms. Chan will attempt to do a review video for Chapter 25 & 26 – please check website for an update of the link.