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Plant Form and Function. Learning Goal: How are plants structurally adapted for survival? Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39) Refer to pg 210-213 in Holtzclaw Ch 39 in Campbell Media resources.

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Plant form and function

Plant Form and Function

Learning Goal: How are plants structurally adapted for survival?

Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)

Refer to pg 210-213 in HoltzclawCh 39 in Campbell Media resources


Try this from last year
Try This! (from last year)

In double fertilization, how is the endosperm formed?

  • The fusing of two sperm and an egg

  • From the epidermis

  • From the fertilization of the egg

  • From the zygote during development

  • From the fusing of a sperm with two polar bodies


Try this
Try This!

In double fertilization, how is the endosperm formed?

  • The fusing of two sperm and an egg

  • From the epidermis

  • From the fertilization of the egg

  • From the zygote during development

  • From the fusing of a sperm with two polar bodies


Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)

You must know:

The three steps to a signal transduction pathway

The role of auxins in plants

The survival benefits of phototropism and photoperiodism use changes in environment to modify plant growth and behaviour

How plants respond to attacks by herbivores and pathogens


Try this1
Try This!

Both plants and animals respond to environmental stimuli. Which of the following statements are true and which ones are false?

  • The processes by which plants and animals perceive environmental changes are equally complex.

  • The processes by which plants and animals perceive environmental changes are often homologous.

  • Unlike animal hormones, plant hormones act only locally.

  • Both plants and animals have physiological cycles called circadian rhythms.


Try this2
Try This!

Both plants and animals respond to environmental stimuli. Which of the following statements are true and which ones are false?

  • The processes by which plants and animals perceive environmental changes are equally complex.TRUE

  • The processes by which plants and animals perceive environmental changes are often homologous.TRUE

  • Unlike animal hormones, plant hormones act only locally. FLASE

  • Both plants and animals have physiological cycles called circadian rhythms.TRUE


Try this3
Try This!

  • What are the morphological differences in dark-grown plants and light-grown plants?


Try this4
Try This!

  • What are the morphological differences in dark-grown plants and light-grown plants?

    • Dark- grown have

      • long stems

      • underdeveloped roots

      • unexpanded leaves

      • shoots lack chlorophyll

But, WHY?




How does this potato change its growth when there is light2
How does this potato change its growth when there is light?

  • Via the Signal Transduction Pathway!

    • The signal (light) is transduced to a response (greening)


Signal transduction review
Signal Transduction - Review

  • Reception

  • Transduction

  • Response


Signal transduction review1
Signal Transduction - Review

  • Reception: Receptors undergo changes in shape due to an environmental stimulus

    • Ex) phytochrome proteins changing in response to light


Signal transduction review2
Signal Transduction - Review

  • Transduction: Amplification of signal through a multistep pathway

    • Allows small signal to produce large cellular response

      • Uses protein kinases (phosphorylation cascade) and second messengers (Ca2+ and cAMP)


Signal transduction review3
Signal Transduction - Review

  • Response: Two ways response is accomplished:

    • Transcriptional Modification:

      • ↑ or ↓ mRNA production (turning genes on/off)

    • Post-Translational Modification:

      • Activates existing enzyme molecules


Signal transduction
Signal Transduction

  • Proteins include:

    • Photosynthesis enzymes

    • Plant growth hormones

      • Auxin levels lower to slow stem growth (focus on leaf growth)


So what was auxin
So…. What was AUXIN?

  • A plant hormone…

  • Yes, plants have hormones too!


Examples of plant hormones
Examples of Plant Hormones

  • Auxins – stimulate elongation of cells within young developing shoots

  • Cytokinins – stimulate cell division

  • Gibberellins – stimulate stem elongation, pollen, fruit, seed development

  • Abscisic acid – promotes stomatal closure during drought stress

  • Ethylene (gas!) – fruit ripening, leaf abscission


Plant hormones
Plant Hormones

  • Hormones: chemical messengers that coordinate the different parts of a multicellular organism

  • Tropism: Plant growth response toward or away from a stimulus

    • Phototropism

    • Gravitropism

  • How does this benefit survival?





Actions of hormones
Actions of hormones…

  • Photoperiodism – physiological response to a photoperiod (relative lengths of day and night)

    • Example: Flowering

      • Short day plants

      • Long day plants

      • Day-neutral plants

  • Circadian rhythms – physiological cycles that have a frequency of about 24 hours



Herbivore defense
Herbivore Defense

Video Clip


Think
Think:

  • Illustrate this statement with an example: “A plant generally responds to environmental cues by adjusting its pattern of growth and development.”


How do plants detect and defend themselves against herbivores and environmental stresses
How do plants detect and defend themselves against herbivores and environmental stresses?

Do you know?

The three steps to a signal transduction pathway

The role of auxins in plants

The survival benefits of phototropism and photoperiodism use changes in environment to modify plant growth and behaviour

How plants respond to attacks by herbivores andpathogens

Try# 1 p. 213, #1-4 p. 215 in Holtz


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