Plant Form and Function
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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. 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. - PowerPoint PPT Presentation
Transcript of Plant Form and Function
Plant Form and FunctionLearning 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)In double fertilization, how is the
endosperm formed?A. The fusing of two sperm and an
egg B. From the epidermisC. From the fertilization of the eggD. From the zygote during
developmentE. From the fusing of a sperm with
two polar bodies
Try This!In double fertilization, how is the
endosperm formed?A. The fusing of two sperm and an
egg B. From the epidermisC. From the fertilization of the eggD. From the zygote during
developmentE. 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
pathwayThe role of auxins in plantsThe 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 This!Both plants and animals respond to
environmental stimuli. Which of the following statements are true and which ones are false?
A. The processes by which plants and animals perceive environmental changes are equally complex.
B. The processes by which plants and animals perceive environmental changes are often homologous.
C. Unlike animal hormones, plant hormones act only locally.
D. Both plants and animals have physiological cycles called circadian rhythms.
Try This!Both plants and animals respond to
environmental stimuli. Which of the following statements are true and which ones are false?
A. The processes by which plants and animals perceive environmental changes are equally complex. TRUE
B. The processes by which plants and animals perceive environmental changes are often homologous. TRUE
C. Unlike animal hormones, plant hormones act only locally. FLASE
D. Both plants and animals have physiological cycles called circadian rhythms. TRUE
Try This!What are the morphological
differences in dark-grown plants and light-grown plants?
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 light?
How does this potato change its growth when there is light?
Via the Signal Transduction Pathway!
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 - ReviewReceptionTransductionResponse
Signal Transduction - ReviewReception: Receptors undergo changes
in shape due to an environmental stimulus◦ Ex) phytochrome proteins changing in response
to light
Signal Transduction - ReviewTransduction: 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 - Review Response: Two ways response is
accomplished:1. Transcriptional Modification:
• ↑ or ↓ mRNA production (turning genes on/off)2. Post-Translational Modification:
• Activates existing enzyme molecules
Signal TransductionProteins include:
◦Photosynthesis enzymes◦Plant growth hormones
Auxin levels lower to slow stem growth (focus on leaf growth)
So…. What was AUXIN?A plant hormone…
Yes, plants have hormones too!
Examples of Plant HormonesAuxins – 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 HormonesHormones: 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?
Phototropism - Mechanism
Phototropism - Mechanism
Phototropism - Mechanism
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
Responses to Mechanical StimuliMimosa Plant
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?
Do you know? The three steps to a signal transduction
pathwayThe role of auxins in plantsThe 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# 1 p. 213, #1-4 p. 215 in Holtz
